## Copyright (C) 1996-2023 The Squid Software Foundation and contributors ## ## Squid software is distributed under GPLv2+ license and includes ## contributions from numerous individuals and organizations. ## Please see the COPYING and CONTRIBUTORS files for details. ## COMMENT_START WELCOME TO @SQUID@ ---------------------------- This is the documentation for the Squid configuration file. This documentation can also be found online at: http://www.squid-cache.org/Doc/config/ You may wish to look at the Squid home page and wiki for the FAQ and other documentation: http://www.squid-cache.org/ http://wiki.squid-cache.org/SquidFaq http://wiki.squid-cache.org/ConfigExamples This documentation shows what the defaults for various directives happen to be. If you don't need to change the default, you should leave the line out of your squid.conf in most cases. In some cases "none" refers to no default setting at all, while in other cases it refers to the value of the option - the comments for that keyword indicate if this is the case. COMMENT_END COMMENT_START Configuration options can be included using the "include" directive. Include takes a list of files to include. Quoting and wildcards are supported. For example, include /path/to/included/file/squid.acl.config Includes can be nested up to a hard-coded depth of 16 levels. This arbitrary restriction is to prevent recursive include references from causing Squid entering an infinite loop whilst trying to load configuration files. Values with byte units Squid accepts size units on some size related directives. All such directives are documented with a default value displaying a unit. Units accepted by Squid are: bytes - byte KB - Kilobyte (1024 bytes) MB - Megabyte GB - Gigabyte Values with time units Time-related directives marked with either "time-units" or "time-units-small" accept a time unit. The supported time units are: nanosecond (time-units-small only) microsecond (time-units-small only) millisecond second minute hour day week fortnight month - 30 days year - 31557790080 milliseconds (just over 365 days) decade Values with spaces, quotes, and other special characters Squid supports directive parameters with spaces, quotes, and other special characters. Surround such parameters with "double quotes". Use the configuration_includes_quoted_values directive to enable or disable that support. Squid supports reading configuration option parameters from external files using the syntax: parameters("/path/filename") For example: acl allowlist dstdomain parameters("/etc/squid/allowlist.txt") Conditional configuration If-statements can be used to make configuration directives depend on conditions: if ... regular configuration directives ... [else ... regular configuration directives ...] endif The else part is optional. The keywords "if", "else", and "endif" must be typed on their own lines, as if they were regular configuration directives. NOTE: An else-if condition is not supported. These individual conditions types are supported: true Always evaluates to true. false Always evaluates to false. = Equality comparison of two integer numbers. SMP-Related Macros The following SMP-related preprocessor macros can be used. ${process_name} expands to the current Squid process "name" (e.g., squid1, squid2, or cache1). ${process_number} expands to the current Squid process identifier, which is an integer number (e.g., 1, 2, 3) unique across all Squid processes of the current service instance. ${service_name} expands into the current Squid service instance name identifier which is provided by -n on the command line. Logformat Macros Logformat macros can be used in many places outside of the logformat directive. In theory, all of the logformat codes can be used as %macros, where they are supported. In practice, a %macro expands as a dash (-) when the transaction does not yet have enough information and a value is needed. There is no definitive list of what tokens are available at the various stages of the transaction. And some information may already be available to Squid but not yet committed where the macro expansion code can access it (report such instances!). The macro will be expanded into a single dash ('-') in such cases. Not all macros have been tested. COMMENT_END # options still not yet ported from 2.7 to 3.x NAME: broken_vary_encoding TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END NAME: cache_vary TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END NAME: error_map TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END NAME: external_refresh_check TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END NAME: location_rewrite_program location_rewrite_access location_rewrite_children location_rewrite_concurrency TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END NAME: refresh_stale_hit TYPE: obsolete DOC_START This option is not yet supported by Squid-3. DOC_END # Options removed in 5.x NAME: dns_v4_first TYPE: obsolete DOC_START Remove this line. Squid no longer supports preferential treatment of DNS A records. DOC_END # Options removed in 4.x NAME: cache_peer_domain cache_host_domain TYPE: obsolete DOC_START Replace with dstdomain ACLs and cache_peer_access. DOC_END NAME: ie_refresh TYPE: obsolete DOC_START Remove this line. The behaviour enabled by this is no longer needed. DOC_END NAME: sslproxy_cafile TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options cafile= instead. DOC_END NAME: sslproxy_capath TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options capath= instead. DOC_END NAME: sslproxy_cipher TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options cipher= instead. DOC_END NAME: sslproxy_client_certificate TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options cert= instead. DOC_END NAME: sslproxy_client_key TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options key= instead. DOC_END NAME: sslproxy_flags TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options flags= instead. DOC_END NAME: sslproxy_options TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options options= instead. DOC_END NAME: sslproxy_version TYPE: obsolete DOC_START Remove this line. Use tls_outgoing_options options= instead. DOC_END # Options removed in 3.5 NAME: hierarchy_stoplist TYPE: obsolete DOC_START Remove this line. Use always_direct or cache_peer_access ACLs instead if you need to prevent cache_peer use. DOC_END # Options removed in 3.4 NAME: log_access TYPE: obsolete DOC_START Remove this line. Use acls with access_log directives to control access logging DOC_END NAME: log_icap TYPE: obsolete DOC_START Remove this line. Use acls with icap_log directives to control icap logging DOC_END # Options Removed in 3.3 NAME: ignore_ims_on_miss TYPE: obsolete DOC_START Remove this line. The HTTP/1.1 feature is now configured by 'cache_miss_revalidate'. DOC_END # Options Removed in 3.2 NAME: balance_on_multiple_ip TYPE: obsolete DOC_START Remove this line. Squid performs a 'Happy Eyeballs' algorithm, this multiple-IP algorithm is not longer relevant. DOC_END NAME: chunked_request_body_max_size TYPE: obsolete DOC_START Remove this line. Squid is now HTTP/1.1 compliant. DOC_END NAME: dns_v4_fallback TYPE: obsolete DOC_START Remove this line. Squid performs a 'Happy Eyeballs' algorithm, the 'fallback' algorithm is no longer relevant. DOC_END NAME: emulate_httpd_log TYPE: obsolete DOC_START Replace this with an access_log directive using the format 'common' or 'combined'. DOC_END NAME: forward_log TYPE: obsolete DOC_START Use a regular access.log with ACL limiting it to MISS events. DOC_END NAME: ftp_list_width TYPE: obsolete DOC_START Remove this line. Configure FTP page display using the CSS controls in errorpages.css instead. DOC_END NAME: ignore_expect_100 TYPE: obsolete DOC_START Remove this line. The HTTP/1.1 feature is now fully supported by default. DOC_END NAME: log_fqdn TYPE: obsolete DOC_START Remove this option from your config. To log FQDN use %>A in the log format. DOC_END NAME: log_ip_on_direct TYPE: obsolete DOC_START Remove this option from your config. To log server or peer names use % #auth_param negotiate children 20 startup=0 idle=1 # #auth_param digest program #auth_param digest children 20 startup=0 idle=1 #auth_param digest realm Squid proxy-caching web server #auth_param digest nonce_garbage_interval 5 minutes #auth_param digest nonce_max_duration 30 minutes #auth_param digest nonce_max_count 50 # #auth_param ntlm program #auth_param ntlm children 20 startup=0 idle=1 # #auth_param basic program #auth_param basic children 5 startup=5 idle=1 #auth_param basic credentialsttl 2 hours DOC_END NAME: authenticate_cache_garbage_interval IFDEF: USE_AUTH TYPE: time_t DEFAULT: 1 hour LOC: Auth::TheConfig.garbageCollectInterval DOC_START The time period between garbage collection across the username cache. This is a trade-off between memory utilization (long intervals - say 2 days) and CPU (short intervals - say 1 minute). Only change if you have good reason to. DOC_END NAME: authenticate_ttl IFDEF: USE_AUTH TYPE: time_t DEFAULT: 1 hour LOC: Auth::TheConfig.credentialsTtl DOC_START The time a user & their credentials stay in the logged in user cache since their last request. When the garbage interval passes, all user credentials that have passed their TTL are removed from memory. DOC_END NAME: authenticate_ip_ttl IFDEF: USE_AUTH TYPE: time_t LOC: Auth::TheConfig.ipTtl DEFAULT: 1 second DOC_START If you use proxy authentication and the 'max_user_ip' ACL, this directive controls how long Squid remembers the IP addresses associated with each user. Use a small value (e.g., 60 seconds) if your users might change addresses quickly, as is the case with dialup. You might be safe using a larger value (e.g., 2 hours) in a corporate LAN environment with relatively static address assignments. DOC_END COMMENT_START ACCESS CONTROLS ----------------------------------------------------------------------------- COMMENT_END NAME: external_acl_type TYPE: externalAclHelper LOC: Config.externalAclHelperList DEFAULT: none DOC_START This option defines external acl classes using a helper program to look up the status external_acl_type name [options] FORMAT /path/to/helper [helper arguments] Options: ttl=n TTL in seconds for cached results (defaults to 3600 for 1 hour) negative_ttl=n TTL for cached negative lookups (default same as ttl) grace=n Percentage remaining of TTL where a refresh of a cached entry should be initiated without needing to wait for a new reply. (default is for no grace period) cache=n The maximum number of entries in the result cache. The default limit is 262144 entries. Each cache entry usually consumes at least 256 bytes. Squid currently does not remove expired cache entries until the limit is reached, so a proxy will sooner or later reach the limit. The expanded FORMAT value is used as the cache key, so if the details in FORMAT are highly variable, a larger cache may be needed to produce reduction in helper load. children-max=n Maximum number of acl helper processes spawned to service external acl lookups of this type. (default 5) children-startup=n Minimum number of acl helper processes to spawn during startup and reconfigure to service external acl lookups of this type. (default 0) children-idle=n Number of acl helper processes to keep ahead of traffic loads. Squid will spawn this many at once whenever load rises above the capabilities of existing processes. Up to the value of children-max. (default 1) concurrency=n concurrency level per process. Only used with helpers capable of processing more than one query at a time. queue-size=N The queue-size option sets the maximum number of queued requests. A request is queued when no existing helper can accept it due to concurrency limit and no new helper can be started due to children-max limit. If the queued requests exceed queue size, the acl is ignored. The default value is set to 2*children-max. protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers. ipv4 / ipv6 IP protocol used to communicate with this helper. The default is to auto-detect IPv6 and use it when available. FORMAT is a series of %macro codes. See logformat directive for a full list of the accepted codes. Although note that at the time of any external ACL being tested data may not be available and thus some %macro expand to '-'. In addition to the logformat codes; when processing external ACLs these additional macros are made available: %ACL The name of the ACL being tested. %DATA The ACL arguments specified in the referencing config 'acl ... external' line, separated by spaces (an "argument string"). see acl external. If there are no ACL arguments %DATA expands to '-'. If you do not specify a DATA macro inside FORMAT, Squid automatically appends %DATA to your FORMAT. Note that Squid-3.x may expand %DATA to whitespace or nothing in this case. By default, Squid applies URL-encoding to each ACL argument inside the argument string. If an explicit encoding modifier is used (e.g., %#DATA), then Squid encodes the whole argument string as a single token (e.g., with %#DATA, spaces between arguments become %20). If SSL is enabled, the following formating codes become available: %USER_CERT SSL User certificate in PEM format %USER_CERTCHAIN SSL User certificate chain in PEM format %USER_CERT_xx SSL User certificate subject attribute xx %USER_CA_CERT_xx SSL User certificate issuer attribute xx NOTE: all other format codes accepted by older Squid versions are deprecated. General request syntax: [channel-ID] FORMAT-values FORMAT-values consists of transaction details expanded with whitespace separation per the config file FORMAT specification using the FORMAT macros listed above. Request values sent to the helper are URL escaped to protect each value in requests against whitespaces. If using protocol=2.5 then the request sent to the helper is not URL escaped to protect against whitespace. NOTE: protocol=3.0 is deprecated as no longer necessary. When using the concurrency= option the protocol is changed by introducing a query channel tag in front of the request/response. The query channel tag is a number between 0 and concurrency-1. This value must be echoed back unchanged to Squid as the first part of the response relating to its request. The helper receives lines expanded per the above format specification and for each input line returns 1 line starting with OK/ERR/BH result code and optionally followed by additional keywords with more details. General result syntax: [channel-ID] result keyword=value ... Result consists of one of the codes: OK the ACL test produced a match. ERR the ACL test does not produce a match. BH An internal error occurred in the helper, preventing a result being identified. The meaning of 'a match' is determined by your squid.conf access control configuration. See the Squid wiki for details. Defined keywords: user= The users name (login) password= The users password (for login= cache_peer option) message= Message describing the reason for this response. Available as %o in error pages. Useful on (ERR and BH results). tag= Apply a tag to a request. Only sets a tag once, does not alter existing tags. log= String to be logged in access.log. Available as %ea in logformat specifications. clt_conn_tag= Associates a TAG with the client TCP connection. Please see url_rewrite_program related documentation for this kv-pair. Any keywords may be sent on any response whether OK, ERR or BH. All response keyword values need to be a single token with URL escaping, or enclosed in double quotes (") and escaped using \ on any double quotes or \ characters within the value. The wrapping double quotes are removed before the value is interpreted by Squid. \r and \n are also replace by CR and LF. Some example key values: user=John%20Smith user="John Smith" user="J. \"Bob\" Smith" DOC_END NAME: acl TYPE: acl LOC: Config.aclList IF USE_OPENSSL DEFAULT: ssl::certHasExpired ssl_error X509_V_ERR_CERT_HAS_EXPIRED DEFAULT: ssl::certNotYetValid ssl_error X509_V_ERR_CERT_NOT_YET_VALID DEFAULT: ssl::certDomainMismatch ssl_error SQUID_X509_V_ERR_DOMAIN_MISMATCH DEFAULT: ssl::certUntrusted ssl_error X509_V_ERR_INVALID_CA X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY X509_V_ERR_CERT_UNTRUSTED DEFAULT: ssl::certSelfSigned ssl_error X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT ENDIF DEFAULT: all src all DEFAULT: manager url_regex -i ^cache_object:// +i ^[^:]+://[^/]+/squid-internal-mgr/ DEFAULT: localhost src 127.0.0.1/32 ::1 DEFAULT: to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1/128 ::/128 DEFAULT: to_linklocal dst 169.254.0.0/16 fe80::/10 DEFAULT: CONNECT method CONNECT DEFAULT_DOC: ACLs all, manager, localhost, to_localhost, to_linklocal, and CONNECT are predefined. DOC_START Defining an Access List Every access list definition must begin with an aclname and acltype, followed by either type-specific arguments or a quoted filename that they are read from. acl aclname acltype argument ... acl aclname acltype "file" ... When using "file", the file should contain one item per line. ACL Options Some acl types supports options which changes their default behaviour: -i,+i By default, regular expressions are CASE-SENSITIVE. To make them case-insensitive, use the -i option. To return case-sensitive use the +i option between patterns, or make a new ACL line without -i. -n Disable lookups and address type conversions. If lookup or conversion is required because the parameter type (IP or domain name) does not match the message address type (domain name or IP), then the ACL would immediately declare a mismatch without any warnings or lookups. -m[=delimiters] Perform a list membership test, interpreting values as comma-separated token lists and matching against individual tokens instead of whole values. The optional "delimiters" parameter specifies one or more alternative non-alphanumeric delimiter characters. non-alphanumeric delimiter characters. -- Used to stop processing all options, in the case the first acl value has '-' character as first character (for example the '-' is a valid domain name) Some acl types require suspending the current request in order to access some external data source. Those which do are marked with the tag [slow], those which don't are marked as [fast]. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for further information ***** ACL TYPES AVAILABLE ***** acl aclname src ip-address/mask ... # clients IP address [fast] acl aclname src addr1-addr2/mask ... # range of addresses [fast] acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow] acl aclname localip ip-address/mask ... # IP address the client connected to [fast] if USE_SQUID_EUI acl aclname arp mac-address ... acl aclname eui64 eui64-address ... # [fast] # MAC (EUI-48) and EUI-64 addresses use xx:xx:xx:xx:xx:xx notation. # # The 'arp' ACL code is not portable to all operating systems. # It works on Linux, Solaris, Windows, FreeBSD, and some other # BSD variants. # # The eui_lookup directive is required to be 'on' (the default) # and Squid built with --enable-eui for MAC/EUI addresses to be # available for this ACL. # # Squid can only determine the MAC/EUI address for IPv4 # clients that are on the same subnet. If the client is on a # different subnet, then Squid cannot find out its address. # # IPv6 protocol does not contain ARP. MAC/EUI is either # encoded directly in the IPv6 address or not available. endif acl aclname clientside_mark mark[/mask] ... # matches CONNMARK of an accepted connection [fast] # DEPRECATED. Use the 'client_connection_mark' instead. acl aclname client_connection_mark mark[/mask] ... # matches CONNMARK of an accepted connection [fast] # # mark and mask are unsigned integers (hex, octal, or decimal). # If multiple marks are given, then the ACL matches if at least # one mark matches. # # Uses netfilter-conntrack library. # Requires building Squid with --enable-linux-netfilter. # # The client, various intermediaries, and Squid itself may set # CONNMARK at various times. The last CONNMARK set wins. This ACL # checks the mark present on an accepted connection or set by # Squid afterwards, depending on the ACL check timing. This ACL # effectively ignores any mark set by other agents after Squid has # accepted the connection. acl aclname srcdomain .foo.com ... # reverse lookup, from client IP [slow] acl aclname dstdomain [-n] .foo.com ... # Destination server from URL [fast] acl aclname srcdom_regex [-i] \.foo\.com ... # regex matching client name [slow] acl aclname dstdom_regex [-n] [-i] \.foo\.com ... # regex matching server [fast] # # For dstdomain and dstdom_regex a reverse lookup is tried if a IP # based URL is used and no match is found. The name "none" is used # if the reverse lookup fails. acl aclname src_as number ... acl aclname dst_as number ... # [fast] # Except for access control, AS numbers can be used for # routing of requests to specific caches. Here's an # example for routing all requests for AS#1241 and only # those to mycache.mydomain.net: # acl asexample dst_as 1241 # cache_peer_access mycache.mydomain.net allow asexample # cache_peer_access mycache_mydomain.net deny all acl aclname peername myPeer ... acl aclname peername_regex [-i] regex-pattern ... # [fast] # match against a named cache_peer entry # set unique name= on cache_peer lines for reliable use. acl aclname time [day-abbrevs] [h1:m1-h2:m2] # [fast] # day-abbrevs: # S - Sunday # M - Monday # T - Tuesday # W - Wednesday # H - Thursday # F - Friday # A - Saturday # h1:m1 must be less than h2:m2 acl aclname url_regex [-i] ^http:// ... # regex matching on whole URL [fast] acl aclname urllogin [-i] [^a-zA-Z0-9] ... # regex matching on URL login field acl aclname urlpath_regex [-i] \.gif$ ... # regex matching on URL path [fast] acl aclname port 80 70 21 0-1024... # destination TCP port [fast] # ranges are alloed acl aclname localport 3128 ... # TCP port the client connected to [fast] # NP: for interception mode this is usually '80' acl aclname myportname 3128 ... # *_port name [fast] acl aclname proto HTTP FTP ... # request protocol [fast] acl aclname method GET POST ... # HTTP request method [fast] acl aclname http_status 200 301 500- 400-403 ... # status code in reply [fast] acl aclname browser [-i] regexp ... # pattern match on User-Agent header (see also req_header below) [fast] acl aclname referer_regex [-i] regexp ... # pattern match on Referer header [fast] # Referer is highly unreliable, so use with care acl aclname ident [-i] username ... # string match on ident output [slow] # use REQUIRED to accept any non-null ident. # # See also: ident_regex. The two ACLs differ only in their parameter # syntax and ident output matching algorithm. acl aclname ident_regex [-i] username_pattern ... # regex match on ident output [slow] acl aclname proxy_auth [-i] username ... # perform http authentication challenge to the client and match against # supplied credentials [slow] # # takes a list of allowed usernames. # use REQUIRED to accept any valid username. # # See proxy_auth_regex for more information. The two ACLs differ only in # their parameter syntax and username matching algorithm. acl aclname proxy_auth_regex [-i] username_pattern ... # perform http authentication challenge to the client and regex match # supplied username [slow] # # Will use proxy authentication in forward-proxy scenarios, and plain # http authenticaiton in reverse-proxy scenarios # # NOTE: when a Proxy-Authentication header is sent but it is not # needed during ACL checking the username is NOT logged # in access.log. # # NOTE: proxy_auth requires a EXTERNAL authentication program # to check username/password combinations (see # auth_param directive). # # NOTE: proxy_auth can't be used in a transparent/intercepting proxy # as the browser needs to be configured for using a proxy in order # to respond to proxy authentication. acl aclname snmp_community string ... # A community string to limit access to your SNMP Agent [fast] # Example: # # acl snmppublic snmp_community public acl aclname maxconn number # This will be matched when the client's IP address has # more than TCP connections established. [fast] # NOTE: This only measures direct TCP links so X-Forwarded-For # indirect clients are not counted. acl aclname max_user_ip [-s] number # This will be matched when the user attempts to log in from more # than different ip addresses. The authenticate_ip_ttl # parameter controls the timeout on the ip entries. [fast] # If -s is specified the limit is strict, denying browsing # from any further IP addresses until the ttl has expired. Without # -s Squid will just annoy the user by "randomly" denying requests. # (the counter is reset each time the limit is reached and a # request is denied) # NOTE: in acceleration mode or where there is mesh of child proxies, # clients may appear to come from multiple addresses if they are # going through proxy farms, so a limit of 1 may cause user problems. acl aclname random probability # Pseudo-randomly match requests. Based on the probability given. # Probability may be written as a decimal (0.333), fraction (1/3) # or ratio of matches:non-matches (3:5). acl aclname req_mime_type [-i] mime-type ... # regex match against the mime type of the request generated # by the client. Can be used to detect file upload or some # types HTTP tunneling requests [fast] # NOTE: This does NOT match the reply. You cannot use this # to match the returned file type. acl aclname req_header header-name [-i] any\.regex\.here # regex match against any of the known request headers. May be # thought of as a superset of "browser", "referer" and "mime-type" # ACL [fast] acl aclname rep_mime_type [-i] mime-type ... # regex match against the mime type of the reply received by # squid. Can be used to detect file download or some # types HTTP tunneling requests. [fast] # NOTE: This has no effect in http_access rules. It only has # effect in rules that affect the reply data stream such as # http_reply_access. acl aclname rep_header header-name [-i] any\.regex\.here # regex match against any of the known reply headers. May be # thought of as a superset of "browser", "referer" and "mime-type" # ACLs [fast] acl aclname external class_name [arguments...] # external ACL lookup via a helper class defined by the # external_acl_type directive [slow] acl aclname user_cert attribute values... # match against attributes in a user SSL certificate # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast] acl aclname ca_cert attribute values... # match against attributes a users issuing CA SSL certificate # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast] acl aclname ext_user [-i] username ... # string match on username returned by external acl helper [slow] # use REQUIRED to accept any non-null user name. # # See also: ext_user_regex. The two ACLs differ only in their parameter # syntax and username matching algorithm. acl aclname ext_user_regex [-i] username_pattern ... # regex match on username returned by external acl helper [slow] acl aclname tag tagvalue ... # string match on tag returned by external acl helper [fast] # DEPRECATED. Only the first tag will match with this ACL. # Use the 'note' ACL instead for handling multiple tag values. acl aclname hier_code codename ... # string match against squid hierarchy code(s); [fast] # e.g., DIRECT, PARENT_HIT, NONE, etc. # # NOTE: This has no effect in http_access rules. It only has # effect in rules that affect the reply data stream such as # http_reply_access. acl aclname note [-m[=delimiters]] name [value ...] # match transaction annotation [fast] # Without values, matches any annotation with a given name. # With value(s), matches any annotation with a given name that # also has one of the given values. # If the -m flag is used, then the value of the named # annotation is interpreted as a list of tokens, and the ACL # matches individual name=token pairs rather than whole # name=value pairs. See "ACL Options" above for more info. # Annotation sources include note and adaptation_meta directives # as well as helper and eCAP responses. acl aclname annotate_transaction [-m[=delimiters]] key=value ... acl aclname annotate_transaction [-m[=delimiters]] key+=value ... # Always matches. [fast] # Used for its side effect: This ACL immediately adds a # key=value annotation to the current master transaction. # The added annotation can then be tested using note ACL and # logged (or sent to helpers) using %note format code. # # Annotations can be specified using replacement and addition # formats. The key=value form replaces old same-key annotation # value(s). The key+=value form appends a new value to the old # same-key annotation. Both forms create a new key=value # annotation if no same-key annotation exists already. If # -m flag is used, then the value is interpreted as a list # and the annotation will contain key=token pair(s) instead of the # whole key=value pair. # # This ACL is especially useful for recording complex multi-step # ACL-driven decisions. For example, the following configuration # avoids logging transactions accepted after aclX matched: # # # First, mark transactions accepted after aclX matched # acl markSpecial annotate_transaction special=true # http_access allow acl001 # ... # http_access deny acl100 # http_access allow aclX markSpecial # # # Second, do not log marked transactions: # acl markedSpecial note special true # access_log ... deny markedSpecial # # # Note that the following would not have worked because aclX # # alone does not determine whether the transaction was allowed: # access_log ... deny aclX # Wrong! # # Warning: This ACL annotates the transaction even when negated # and even if subsequent ACLs fail to match. For example, the # following three rules will have exactly the same effect as far # as annotations set by the "mark" ACL are concerned: # # some_directive acl1 ... mark # rule matches if mark is reached # some_directive acl1 ... !mark # rule never matches # some_directive acl1 ... mark !all # rule never matches acl aclname annotate_client [-m[=delimiters]] key=value ... acl aclname annotate_client [-m[=delimiters]] key+=value ... # # Always matches. [fast] # Used for its side effect: This ACL immediately adds a # key=value annotation to the current client-to-Squid # connection. Connection annotations are propagated to the current # and all future master transactions on the annotated connection. # See the annotate_transaction ACL for details. # # For example, the following configuration avoids rewriting URLs # of transactions bumped by SslBump: # # # First, mark bumped connections: # acl markBumped annotate_client bumped=true # ssl_bump peek acl1 # ssl_bump stare acl2 # ssl_bump bump acl3 markBumped # ssl_bump splice all # # # Second, do not send marked transactions to the redirector: # acl markedBumped note bumped true # url_rewrite_access deny markedBumped # # # Note that the following would not have worked because acl3 alone # # does not determine whether the connection is going to be bumped: # url_rewrite_access deny acl3 # Wrong! acl aclname adaptation_service service ... # Matches the name of any icap_service, ecap_service, # adaptation_service_set, or adaptation_service_chain that Squid # has used (or attempted to use) for the master transaction. # This ACL must be defined after the corresponding adaptation # service is named in squid.conf. This ACL is usable with # adaptation_meta because it starts matching immediately after # the service has been selected for adaptation. acl aclname transaction_initiator initiator ... # Matches transaction's initiator [fast] # # Supported initiators are: # esi: matches transactions fetching ESI resources # certificate-fetching: matches transactions fetching # a missing intermediate TLS certificate # cache-digest: matches transactions fetching Cache Digests # from a cache_peer # htcp: matches HTCP requests from peers # icp: matches ICP requests to peers # icmp: matches ICMP RTT database (NetDB) requests to peers # asn: matches asns db requests # internal: matches any of the above # client: matches transactions containing an HTTP or FTP # client request received at a Squid *_port # all: matches any transaction, including internal transactions # without a configurable initiator and hopefully rare # transactions without a known-to-Squid initiator # # Multiple initiators are ORed. acl aclname has component # matches a transaction "component" [fast] # # Supported transaction components are: # request: transaction has a request header (at least) # response: transaction has a response header (at least) # ALE: transaction has an internally-generated Access Log Entry # structure; bugs notwithstanding, all transaction have it # # For example, the following configuration helps when dealing with HTTP # clients that close connections without sending a request header: # # acl hasRequest has request # acl logMe note important_transaction # # avoid "logMe ACL is used in context without an HTTP request" warnings # access_log ... logformat=detailed hasRequest logMe # # log request-less transactions, instead of ignoring them # access_log ... logformat=brief !hasRequest # # Multiple components are not supported for one "acl" rule, but # can be specified (and are ORed) using multiple same-name rules: # # # OK, this strange logging daemon needs request or response, # # but can work without either a request or a response: # acl hasWhatMyLoggingDaemonNeeds has request # acl hasWhatMyLoggingDaemonNeeds has response acl aclname at_step step # match against the current request processing step [fast] # Valid steps are: # GeneratingCONNECT: Generating HTTP CONNECT request headers IF USE_OPENSSL # The following ssl_bump processing steps are recognized: # SslBump1: After getting TCP-level and HTTP CONNECT info. # SslBump2: After getting SSL Client Hello info. # SslBump3: After getting SSL Server Hello info. ENDIF IF USE_OPENSSL acl aclname ssl_error errorname # match against SSL certificate validation error [fast] # # For valid error names see in @DEFAULT_ERROR_DIR@/templates/error-details.txt # template file. # # The following can be used as shortcuts for certificate properties: # [ssl::]certHasExpired: the "not after" field is in the past # [ssl::]certNotYetValid: the "not before" field is in the future # [ssl::]certUntrusted: The certificate issuer is not to be trusted. # [ssl::]certSelfSigned: The certificate is self signed. # [ssl::]certDomainMismatch: The certificate CN domain does not # match the name the name of the host we are connecting to. # # The ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch, # ssl::certUntrusted, and ssl::certSelfSigned can also be used as # predefined ACLs, just like the 'all' ACL. # # NOTE: The ssl_error ACL is only supported with sslproxy_cert_error, # sslproxy_cert_sign, and sslproxy_cert_adapt options. acl aclname server_cert_fingerprint [-sha1] fingerprint # match against server SSL certificate fingerprint [fast] # # The fingerprint is the digest of the DER encoded version # of the whole certificate. The user should use the form: XX:XX:... # Optional argument specifies the digest algorithm to use. # The SHA1 digest algorithm is the default and is currently # the only algorithm supported (-sha1). acl aclname ssl::server_name [option] .foo.com ... # matches server name obtained from various sources [fast] # # The ACL computes server name(s) using such information sources as # CONNECT request URI, TLS client SNI, and TLS server certificate # subject (CN and SubjectAltName). The computed server name(s) usually # change with each SslBump step, as more info becomes available: # * SNI is used as the server name instead of the request URI, # * subject name(s) from the server certificate (CN and # SubjectAltName) are used as the server names instead of SNI. # # When the ACL computes multiple server names, matching any single # computed name is sufficient for the ACL to match. # # The "none" name can be used to match transactions where the ACL # could not compute the server name using any information source # that was both available and allowed to be used by the ACL options at # the ACL evaluation time. # # Unlike dstdomain, this ACL does not perform DNS lookups. # # An ACL option below may be used to restrict what information # sources are used to extract the server names from: # # --client-requested # The server name is SNI regardless of what the server says. # --server-provided # The server name(s) are the certificate subject name(s), regardless # of what the client has requested. If the server certificate is # unavailable, then the name is "none". # --consensus # The server name is either SNI (if SNI matches at least one of the # certificate subject names) or "none" (otherwise). When the server # certificate is unavailable, the consensus server name is SNI. # # Combining multiple options in one ACL is a fatal configuration # error. # # For all options: If no SNI is available, then the CONNECT request # target (a.k.a. URI) is used instead of SNI (for an intercepted # connection, this target is the destination IP address). acl aclname ssl::server_name_regex [-i] \.foo\.com ... # regex matches server name obtained from various sources [fast] acl aclname connections_encrypted # matches transactions with all HTTP messages received over TLS # transport connections. [fast] # # The master transaction deals with HTTP messages received from # various sources. All sources used by the master transaction in the # past are considered by the ACL. The following rules define whether # a given message source taints the entire master transaction, # resulting in ACL mismatches: # # * The HTTP client transport connection is not TLS. # * An adaptation service connection-encryption flag is off. # * The peer or origin server transport connection is not TLS. # # Caching currently does not affect these rules. This cache ignorance # implies that only the current HTTP client transport and REQMOD # services status determine whether this ACL matches a from-cache # transaction. The source of the cached response does not have any # effect on future transaction that use the cached response without # revalidation. This may change. # # DNS, ICP, and HTCP exchanges during the master transaction do not # affect these rules. ENDIF acl aclname any-of acl1 acl2 ... # match any one of the acls [fast or slow] # The first matching ACL stops further ACL evaluation. # # ACLs from multiple any-of lines with the same name are ORed. # For example, A = (a1 or a2) or (a3 or a4) can be written as # acl A any-of a1 a2 # acl A any-of a3 a4 # # This group ACL is fast if all evaluated ACLs in the group are fast # and slow otherwise. acl aclname all-of acl1 acl2 ... # match all of the acls [fast or slow] # The first mismatching ACL stops further ACL evaluation. # # ACLs from multiple all-of lines with the same name are ORed. # For example, B = (b1 and b2) or (b3 and b4) can be written as # acl B all-of b1 b2 # acl B all-of b3 b4 # # This group ACL is fast if all evaluated ACLs in the group are fast # and slow otherwise. Examples: acl macaddress arp 09:00:2b:23:45:67 acl myexample dst_as 1241 acl password proxy_auth REQUIRED acl fileupload req_mime_type -i ^multipart/form-data$ acl javascript rep_mime_type -i ^application/x-javascript$ NOCOMMENT_START # # Recommended minimum configuration: # # Example rule allowing access from your local networks. # Adapt to list your (internal) IP networks from where browsing # should be allowed acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN) acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN) acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN) acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN) acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN) acl localnet src fc00::/7 # RFC 4193 local private network range acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines acl SSL_ports port 443 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 # https acl Safe_ports port 70 # gopher acl Safe_ports port 210 # wais acl Safe_ports port 1025-65535 # unregistered ports acl Safe_ports port 280 # http-mgmt acl Safe_ports port 488 # gss-http acl Safe_ports port 591 # filemaker acl Safe_ports port 777 # multiling http NOCOMMENT_END DOC_END NAME: proxy_protocol_access TYPE: acl_access LOC: Config.accessList.proxyProtocol DEFAULT: none DEFAULT_DOC: all TCP connections to ports with require-proxy-header will be denied DOC_START Determine which client proxies can be trusted to provide correct information regarding real client IP address using PROXY protocol. Requests may pass through a chain of several other proxies before reaching us. The original source details may by sent in: * HTTP message Forwarded header, or * HTTP message X-Forwarded-For header, or * PROXY protocol connection header. This directive is solely for validating new PROXY protocol connections received from a port flagged with require-proxy-header. It is checked only once after TCP connection setup. A deny match results in TCP connection closure. An allow match is required for Squid to permit the corresponding TCP connection, before Squid even looks for HTTP request headers. If there is an allow match, Squid starts using PROXY header information to determine the source address of the connection for all future ACL checks, logging, etc. SECURITY CONSIDERATIONS: Any host from which we accept client IP details can place incorrect information in the relevant header, and Squid will use the incorrect information as if it were the source address of the request. This may enable remote hosts to bypass any access control restrictions that are based on the client's source addresses. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: follow_x_forwarded_for TYPE: acl_access IFDEF: FOLLOW_X_FORWARDED_FOR LOC: Config.accessList.followXFF DEFAULT_IF_NONE: deny all DEFAULT_DOC: X-Forwarded-For header will be ignored. DOC_START Determine which client proxies can be trusted to provide correct information regarding real client IP address. Requests may pass through a chain of several other proxies before reaching us. The original source details may by sent in: * HTTP message Forwarded header, or * HTTP message X-Forwarded-For header, or * PROXY protocol connection header. PROXY protocol connections are controlled by the proxy_protocol_access directive which is checked before this. If a request reaches us from a source that is allowed by this directive, then we trust the information it provides regarding the IP of the client it received from (if any). For the purpose of ACLs used in this directive the src ACL type always matches the address we are testing and srcdomain matches its rDNS. On each HTTP request Squid checks for X-Forwarded-For header fields. If found the header values are iterated in reverse order and an allow match is required for Squid to continue on to the next value. The verification ends when a value receives a deny match, cannot be tested, or there are no more values to test. NOTE: Squid does not yet follow the Forwarded HTTP header. The end result of this process is an IP address that we will refer to as the indirect client address. This address may be treated as the client address for access control, ICAP, delay pools and logging, depending on the acl_uses_indirect_client, icap_uses_indirect_client, delay_pool_uses_indirect_client, log_uses_indirect_client and tproxy_uses_indirect_client options. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. SECURITY CONSIDERATIONS: Any host from which we accept client IP details can place incorrect information in the relevant header, and Squid will use the incorrect information as if it were the source address of the request. This may enable remote hosts to bypass any access control restrictions that are based on the client's source addresses. For example: acl localhost src 127.0.0.1 acl my_other_proxy srcdomain .proxy.example.com follow_x_forwarded_for allow localhost follow_x_forwarded_for allow my_other_proxy DOC_END NAME: acl_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR DEFAULT: on LOC: Config.onoff.acl_uses_indirect_client DOC_START Controls whether the indirect client address (see follow_x_forwarded_for) is used instead of the direct client address in acl matching. NOTE: maxconn ACL considers direct TCP links and indirect clients will always have zero. So no match. DOC_END NAME: delay_pool_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_DELAY_POOLS DEFAULT: on LOC: Config.onoff.delay_pool_uses_indirect_client DOC_START Controls whether the indirect client address (see follow_x_forwarded_for) is used instead of the direct client address in delay pools. DOC_END NAME: log_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR DEFAULT: on LOC: Config.onoff.log_uses_indirect_client DOC_START Controls whether the indirect client address (see follow_x_forwarded_for) is used instead of the direct client address in the access log. DOC_END NAME: tproxy_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER DEFAULT: off LOC: Config.onoff.tproxy_uses_indirect_client DOC_START Controls whether the indirect client address (see follow_x_forwarded_for) is used instead of the direct client address when spoofing the outgoing client. This has no effect on requests arriving in non-tproxy mode ports. SECURITY WARNING: Usage of this option is dangerous and should not be used trivially. Correct configuration of follow_x_forwarded_for with a limited set of trusted sources is required to prevent abuse of your proxy. DOC_END NAME: spoof_client_ip TYPE: acl_access LOC: Config.accessList.spoof_client_ip DEFAULT: none DEFAULT_DOC: Allow spoofing on all TPROXY traffic. DOC_START Control client IP address spoofing of TPROXY traffic based on defined access lists. spoof_client_ip allow|deny [!]aclname ... If there are no "spoof_client_ip" lines present, the default is to "allow" spoofing of any suitable request. Note that the cache_peer "no-tproxy" option overrides this ACL. This clause supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: http_access TYPE: acl_access LOC: Config.accessList.http DEFAULT_IF_NONE: deny all DEFAULT_DOC: Deny, unless rules exist in squid.conf. DOC_START Allowing or Denying access based on defined access lists To allow or deny a message received on an HTTP, HTTPS, or FTP port: http_access allow|deny [!]aclname ... NOTE on default values: If there are no "access" lines present, the default is to deny the request. If none of the "access" lines cause a match, the default is the opposite of the last line in the list. If the last line was deny, the default is allow. Conversely, if the last line is allow, the default will be deny. For these reasons, it is a good idea to have an "deny all" entry at the end of your access lists to avoid potential confusion. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. NOCOMMENT_START # # Recommended minimum Access Permission configuration: # # Deny requests to certain unsafe ports http_access deny !Safe_ports # Deny CONNECT to other than secure SSL ports http_access deny CONNECT !SSL_ports # Only allow cachemgr access from localhost http_access allow localhost manager http_access deny manager # This default configuration only allows localhost requests because a more # permissive Squid installation could introduce new attack vectors into the # network by proxying external TCP connections to unprotected services. http_access allow localhost # The two deny rules below are unnecessary in this default configuration # because they are followed by a "deny all" rule. However, they may become # critically important when you start allowing external requests below them. # Protect web applications running on the same server as Squid. They often # assume that only local users can access them at "localhost" ports. http_access deny to_localhost # Protect cloud servers that provide local users with sensitive info about # their server via certain well-known link-local (a.k.a. APIPA) addresses. http_access deny to_linklocal # # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # # For example, to allow access from your local networks, you may uncomment the # following rule (and/or add rules that match your definition of "local"): # http_access allow localnet # And finally deny all other access to this proxy http_access deny all NOCOMMENT_END DOC_END NAME: adapted_http_access http_access2 TYPE: acl_access LOC: Config.accessList.adapted_http DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. DOC_START Allowing or Denying access based on defined access lists Essentially identical to http_access, but runs after redirectors and ICAP/eCAP adaptation. Allowing access control based on their output. If not set then only http_access is used. DOC_END NAME: http_reply_access TYPE: acl_access LOC: Config.accessList.reply DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. DOC_START Allow replies to client requests. This is complementary to http_access. http_reply_access allow|deny [!] aclname ... NOTE: if there are no access lines present, the default is to allow all replies. If none of the access lines cause a match the opposite of the last line will apply. Thus it is good practice to end the rules with an "allow all" or "deny all" entry. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: icp_access TYPE: acl_access LOC: Config.accessList.icp DEFAULT: none DEFAULT_DOC: Deny, unless rules exist in squid.conf. DOC_START Allowing or Denying access to the ICP port based on defined access lists icp_access allow|deny [!]aclname ... NOTE: The default if no icp_access lines are present is to deny all traffic. This default may cause problems with peers using ICP. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # Allow ICP queries from local networks only #icp_access allow localnet #icp_access deny all DOC_END NAME: htcp_access IFDEF: USE_HTCP TYPE: acl_access LOC: Config.accessList.htcp DEFAULT: none DEFAULT_DOC: Deny, unless rules exist in squid.conf. DOC_START Allowing or Denying access to the HTCP port based on defined access lists htcp_access allow|deny [!]aclname ... See also htcp_clr_access for details on access control for cache purge (CLR) HTCP messages. NOTE: The default if no htcp_access lines are present is to deny all traffic. This default may cause problems with peers using the htcp option. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # Allow HTCP queries from local networks only #htcp_access allow localnet #htcp_access deny all DOC_END NAME: htcp_clr_access IFDEF: USE_HTCP TYPE: acl_access LOC: Config.accessList.htcp_clr DEFAULT: none DEFAULT_DOC: Deny, unless rules exist in squid.conf. DOC_START Allowing or Denying access to purge content using HTCP based on defined access lists. See htcp_access for details on general HTCP access control. htcp_clr_access allow|deny [!]aclname ... This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # Allow HTCP CLR requests from trusted peers acl htcp_clr_peer src 192.0.2.2 2001:DB8::2 htcp_clr_access allow htcp_clr_peer htcp_clr_access deny all DOC_END NAME: miss_access TYPE: acl_access LOC: Config.accessList.miss DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. DOC_START Determines whether network access is permitted when satisfying a request. For example; to force your neighbors to use you as a sibling instead of a parent. acl localclients src 192.0.2.0/24 2001:DB8::a:0/64 miss_access deny !localclients miss_access allow all This means only your local clients are allowed to fetch relayed/MISS replies from the network and all other clients can only fetch cached objects (HITs). The default for this setting allows all clients who passed the http_access rules to relay via this proxy. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: ident_lookup_access TYPE: acl_access IFDEF: USE_IDENT DEFAULT: none DEFAULT_DOC: Unless rules exist in squid.conf, IDENT is not fetched. LOC: Ident::TheConfig.identLookup DOC_START A list of ACL elements which, if matched, cause an ident (RFC 931) lookup to be performed for this request. For example, you might choose to always perform ident lookups for your main multi-user Unix boxes, but not for your Macs and PCs. By default, ident lookups are not performed for any requests. To enable ident lookups for specific client addresses, you can follow this example: acl ident_aware_hosts src 198.168.1.0/24 ident_lookup_access allow ident_aware_hosts ident_lookup_access deny all Only src type ACL checks are fully supported. A srcdomain ACL might work at times, but it will not always provide the correct result. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: reply_body_max_size COMMENT: size [acl acl...] TYPE: acl_b_size_t DEFAULT: none DEFAULT_DOC: No limit is applied. LOC: Config.ReplyBodySize DOC_START This option specifies the maximum size of a reply body. It can be used to prevent users from downloading very large files, such as MP3's and movies. When the reply headers are received, the reply_body_max_size lines are processed, and the first line where all (if any) listed ACLs are true is used as the maximum body size for this reply. This size is checked twice. First when we get the reply headers, we check the content-length value. If the content length value exists and is larger than the allowed size, the request is denied and the user receives an error message that says "the request or reply is too large." If there is no content-length, and the reply size exceeds this limit, the client's connection is just closed and they will receive a partial reply. WARNING: downstream caches probably can not detect a partial reply if there is no content-length header, so they will cache partial responses and give them out as hits. You should NOT use this option if you have downstream caches. WARNING: A maximum size smaller than the size of squid's error messages will cause an infinite loop and crash squid. Ensure that the smallest non-zero value you use is greater that the maximum header size plus the size of your largest error page. If you set this parameter none (the default), there will be no limit imposed. Configuration Format is: reply_body_max_size SIZE UNITS [acl ...] ie. reply_body_max_size 10 MB DOC_END NAME: on_unsupported_protocol TYPE: on_unsupported_protocol LOC: Config.accessList.on_unsupported_protocol DEFAULT: none DEFAULT_DOC: Respond with an error message to unidentifiable traffic DOC_START Determines Squid behavior when encountering strange requests at the beginning of an accepted TCP connection or the beginning of a bumped CONNECT tunnel. Controlling Squid reaction to unexpected traffic is especially useful in interception environments where Squid is likely to see connections for unsupported protocols that Squid should either terminate or tunnel at TCP level. on_unsupported_protocol [!]acl ... The first matching action wins. Only fast ACLs are supported. Supported actions are: tunnel: Establish a TCP connection with the intended server and blindly shovel TCP packets between the client and server. respond: Respond with an error message, using the transfer protocol for the Squid port that received the request (e.g., HTTP for connections intercepted at the http_port). This is the default. Squid expects the following traffic patterns: http_port: a plain HTTP request https_port: SSL/TLS handshake followed by an [encrypted] HTTP request ftp_port: a plain FTP command (no on_unsupported_protocol support yet!) CONNECT tunnel on http_port: same as https_port CONNECT tunnel on https_port: same as https_port Currently, this directive has effect on intercepted connections and bumped tunnels only. Other cases are not supported because Squid cannot know the intended destination of other traffic. For example: # define what Squid errors indicate receiving non-HTTP traffic: acl foreignProtocol squid_error ERR_PROTOCOL_UNKNOWN ERR_TOO_BIG # define what Squid errors indicate receiving nothing: acl serverTalksFirstProtocol squid_error ERR_REQUEST_START_TIMEOUT # tunnel everything that does not look like HTTP: on_unsupported_protocol tunnel foreignProtocol # tunnel if we think the client waits for the server to talk first: on_unsupported_protocol tunnel serverTalksFirstProtocol # in all other error cases, just send an HTTP "error page" response: on_unsupported_protocol respond all See also: squid_error ACL DOC_END NAME: auth_schemes TYPE: AuthSchemes IFDEF: USE_AUTH LOC: Auth::TheConfig.schemeAccess DEFAULT: none DEFAULT_DOC: use all auth_param schemes in their configuration order DOC_START Use this directive to customize authentication schemes presence and order in Squid's Unauthorized and Authentication Required responses. auth_schemes scheme1,scheme2,... [!]aclname ... where schemeN is the name of one of the authentication schemes configured using auth_param directives. At least one scheme name is required. Multiple scheme names are separated by commas. Either avoid whitespace or quote the entire schemes list. A special "ALL" scheme name expands to all auth_param-configured schemes in their configuration order. This directive cannot be used to configure Squid to offer no authentication schemes at all. The first matching auth_schemes rule determines the schemes order for the current Authentication Required transaction. Note that the future response is not yet available during auth_schemes evaluation. If this directive is not used or none of its rules match, then Squid responds with all configured authentication schemes in the order of auth_param directives in the configuration file. This directive does not determine when authentication is used or how each authentication scheme authenticates clients. The following example sends basic and negotiate authentication schemes, in that order, when requesting authentication of HTTP requests matching the isIE ACL (not shown) while sending all auth_param schemes in their configuration order to other clients: auth_schemes basic,negotiate isIE auth_schemes ALL all # explicit default This directive supports fast ACLs only. See also: auth_param. DOC_END COMMENT_START NETWORK OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: http_port ascii_port TYPE: PortCfg DEFAULT: none LOC: HttpPortList DOC_START Usage: port [mode] [options] hostname:port [mode] [options] 1.2.3.4:port [mode] [options] The socket addresses where Squid will listen for HTTP client requests. You may specify multiple socket addresses. There are three forms: port alone, hostname with port, and IP address with port. If you specify a hostname or IP address, Squid binds the socket to that specific address. Most likely, you do not need to bind to a specific address, so you can use the port number alone. If you are running Squid in accelerator mode, you probably want to listen on port 80 also, or instead. The -a command line option may be used to specify additional port(s) where Squid listens for proxy request. Such ports will be plain proxy ports with no options. You may specify multiple socket addresses on multiple lines. Modes: intercept Support for IP-Layer NAT interception delivering traffic to this Squid port. NP: disables authentication on the port. tproxy Support Linux TPROXY (or BSD divert-to) with spoofing of outgoing connections using the client IP address. NP: disables authentication on the port. accel Accelerator / reverse proxy mode ssl-bump For each CONNECT request allowed by ssl_bump ACLs, establish secure connection with the client and with the server, decrypt HTTPS messages as they pass through Squid, and treat them as unencrypted HTTP messages, becoming the man-in-the-middle. The ssl_bump option is required to fully enable bumping of CONNECT requests. Omitting the mode flag causes default forward proxy mode to be used. Accelerator Mode Options: defaultsite=domainname What to use for the Host: header if it is not present in a request. Determines what site (not origin server) accelerators should consider the default. no-vhost Disable using HTTP/1.1 Host header for virtual domain support. protocol= Protocol to reconstruct accelerated and intercepted requests with. Defaults to HTTP/1.1 for http_port and HTTPS/1.1 for https_port. When an unsupported value is configured Squid will produce a FATAL error. Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1 vport Virtual host port support. Using the http_port number instead of the port passed on Host: headers. vport=NN Virtual host port support. Using the specified port number instead of the port passed on Host: headers. act-as-origin Act as if this Squid is the origin server. This currently means generate new Date: and Expires: headers on HIT instead of adding Age:. ignore-cc Ignore request Cache-Control headers. WARNING: This option violates HTTP specifications if used in non-accelerator setups. allow-direct Allow direct forwarding in accelerator mode. Normally accelerated requests are denied direct forwarding as if never_direct was used. WARNING: this option opens accelerator mode to security vulnerabilities usually only affecting in interception mode. Make sure to protect forwarding with suitable http_access rules when using this. SSL Bump Mode Options: In addition to these options ssl-bump requires TLS/SSL options. generate-host-certificates[=] Dynamically create SSL server certificates for the destination hosts of bumped CONNECT requests.When enabled, the cert and key options are used to sign generated certificates. Otherwise generated certificate will be selfsigned. If there is a CA certificate lifetime of the generated certificate equals lifetime of the CA certificate. If generated certificate is selfsigned lifetime is three years. This option is enabled by default when ssl-bump is used. See the ssl-bump option above for more information. dynamic_cert_mem_cache_size=SIZE Approximate total RAM size spent on cached generated certificates. If set to zero, caching is disabled. The default value is 4MB. TLS / SSL Options: tls-cert= Path to file containing an X.509 certificate (PEM format) to be used in the TLS handshake ServerHello. If this certificate is constrained by KeyUsage TLS feature it must allow HTTP server usage, along with any additional restrictions imposed by your choice of options= settings. When OpenSSL is used this file may also contain a chain of intermediate CA certificates to send in the TLS handshake. When GnuTLS is used this option (and any paired tls-key= option) may be repeated to load multiple certificates for different domains. Also, when generate-host-certificates=on is configured the first tls-cert= option must be a CA certificate capable of signing the automatically generated certificates. tls-key= Path to a file containing private key file (PEM format) for the previous tls-cert= option. If tls-key= is not specified tls-cert= is assumed to reference a PEM file containing both the certificate and private key. cipher= Colon separated list of supported ciphers. NOTE: some ciphers such as EDH ciphers depend on additional settings. If those settings are omitted the ciphers may be silently ignored by the OpenSSL library. options= Various SSL implementation options. The most important being: NO_SSLv3 Disallow the use of SSLv3 NO_TLSv1 Disallow the use of TLSv1.0 NO_TLSv1_1 Disallow the use of TLSv1.1 NO_TLSv1_2 Disallow the use of TLSv1.2 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges SINGLE_ECDH_USE Enable ephemeral ECDH key exchange. The adopted curve should be specified using the tls-dh option. NO_TICKET Disable use of RFC5077 session tickets. Some servers may have problems understanding the TLS extension due to ambiguous specification in RFC4507. ALL Enable various bug workarounds suggested as "harmless" by OpenSSL Be warned that this reduces SSL/TLS strength to some attacks. See the OpenSSL SSL_CTX_set_options documentation for a more complete list. clientca= File containing the list of CAs to use when requesting a client certificate. tls-cafile= PEM file containing CA certificates to use when verifying client certificates. If not configured clientca will be used. May be repeated to load multiple files. capath= Directory containing additional CA certificates and CRL lists to use when verifying client certificates. Requires OpenSSL or LibreSSL. crlfile= File of additional CRL lists to use when verifying the client certificate, in addition to CRLs stored in the capath. Implies VERIFY_CRL flag below. tls-dh=[curve:]file File containing DH parameters for temporary/ephemeral DH key exchanges, optionally prefixed by a curve for ephemeral ECDH key exchanges. See OpenSSL documentation for details on how to create the DH parameter file. Supported curves for ECDH can be listed using the "openssl ecparam -list_curves" command. WARNING: EDH and EECDH ciphers will be silently disabled if this option is not set. sslflags= Various flags modifying the use of SSL: DELAYED_AUTH Don't request client certificates immediately, but wait until acl processing requires a certificate (not yet implemented). CONDITIONAL_AUTH Request a client certificate during the TLS handshake, but ignore certificate absence in the TLS client Hello. If the client does supply a certificate, it is validated. NO_SESSION_REUSE Don't allow for session reuse. Each connection will result in a new SSL session. VERIFY_CRL Verify CRL lists when accepting client certificates. VERIFY_CRL_ALL Verify CRL lists for all certificates in the client certificate chain. tls-default-ca[=off] Whether to use the system Trusted CAs. Default is OFF. tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1. sslcontext= SSL session ID context identifier. Other Options: connection-auth[=on|off] use connection-auth=off to tell Squid to prevent forwarding Microsoft connection oriented authentication (NTLM, Negotiate and Kerberos) disable-pmtu-discovery= Control Path-MTU discovery usage: off lets OS decide on what to do (default). transparent disable PMTU discovery when transparent support is enabled. always disable always PMTU discovery. In many setups of transparently intercepting proxies Path-MTU discovery can not work on traffic towards the clients. This is the case when the intercepting device does not fully track connections and fails to forward ICMP must fragment messages to the cache server. If you have such setup and experience that certain clients sporadically hang or never complete requests set disable-pmtu-discovery option to 'transparent'. name= Specifies a internal name for the port. Defaults to the port specification (port or addr:port) tcpkeepalive[=idle,interval,timeout] Enable TCP keepalive probes of idle connections. In seconds; idle is the initial time before TCP starts probing the connection, interval how often to probe, and timeout the time before giving up. require-proxy-header Require PROXY protocol version 1 or 2 connections. The proxy_protocol_access is required to permit downstream proxies which can be trusted. worker-queues Ask TCP stack to maintain a dedicated listening queue for each worker accepting requests at this port. Requires TCP stack that supports the SO_REUSEPORT socket option. SECURITY WARNING: Enabling worker-specific queues allows any process running as Squid's effective user to easily accept requests destined to this port. If you run Squid on a dual-homed machine with an internal and an external interface we recommend you to specify the internal address:port in http_port. This way Squid will only be visible on the internal address. NOCOMMENT_START # Squid normally listens to port 3128 http_port @DEFAULT_HTTP_PORT@ NOCOMMENT_END DOC_END NAME: https_port IFDEF: USE_GNUTLS||USE_OPENSSL TYPE: PortCfg DEFAULT: none LOC: HttpPortList DOC_START Usage: [ip:]port [mode] tls-cert=certificate.pem [options] The socket address where Squid will listen for client requests made over TLS or SSL connections. Commonly referred to as HTTPS. This is most useful for situations where you are running squid in accelerator mode and you want to do the TLS work at the accelerator level. You may specify multiple socket addresses on multiple lines, each with their own certificate and/or options. The tls-cert= option is mandatory on HTTPS ports. See http_port for a list of modes and options. DOC_END NAME: ftp_port TYPE: PortCfg DEFAULT: none LOC: FtpPortList DOC_START Enables Native FTP proxy by specifying the socket address where Squid listens for FTP client requests. See http_port directive for various ways to specify the listening address and mode. Usage: ftp_port address [mode] [options] WARNING: This is a new, experimental, complex feature that has seen limited production exposure. Some Squid modules (e.g., caching) do not currently work with native FTP proxying, and many features have not even been tested for compatibility. Test well before deploying! Native FTP proxying differs substantially from proxying HTTP requests with ftp:// URIs because Squid works as an FTP server and receives actual FTP commands (rather than HTTP requests with FTP URLs). Native FTP commands accepted at ftp_port are internally converted or wrapped into HTTP-like messages. The same happens to Native FTP responses received from FTP origin servers. Those HTTP-like messages are shoveled through regular access control and adaptation layers between the FTP client and the FTP origin server. This allows Squid to examine, adapt, block, and log FTP exchanges. Squid reuses most HTTP mechanisms when shoveling wrapped FTP messages. For example, http_access and adaptation_access directives are used. Modes: intercept Same as http_port intercept. The FTP origin address is determined based on the intended destination of the intercepted connection. tproxy Support Linux TPROXY for spoofing outgoing connections using the client IP address. NP: disables authentication and maybe IPv6 on the port. By default (i.e., without an explicit mode option), Squid extracts the FTP origin address from the login@origin parameter of the FTP USER command. Many popular FTP clients support such native FTP proxying. Options: name=token Specifies an internal name for the port. Defaults to the port address. Usable with myportname ACL. ftp-track-dirs Enables tracking of FTP directories by injecting extra PWD commands and adjusting Request-URI (in wrapping HTTP requests) to reflect the current FTP server directory. Tracking is disabled by default. protocol=FTP Protocol to reconstruct accelerated and intercepted requests with. Defaults to FTP. No other accepted values have been tested with. An unsupported value results in a FATAL error. Accepted values are FTP, HTTP (or HTTP/1.1), and HTTPS (or HTTPS/1.1). Other http_port modes and options that are not specific to HTTP and HTTPS may also work. DOC_END NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp TYPE: acl_tos DEFAULT: none LOC: Ip::Qos::TheConfig.tosToServer DOC_START Allows you to select a TOS/Diffserv value for packets outgoing on the server side, based on an ACL. tcp_outgoing_tos ds-field [!]aclname ... Example where normal_service_net uses the TOS value 0x00 and good_service_net uses 0x20 acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.1.0/24 tcp_outgoing_tos 0x00 normal_service_net tcp_outgoing_tos 0x20 good_service_net TOS/DSCP values really only have local significance - so you should know what you're specifying. For more information, see RFC2474, RFC2475, and RFC3260. The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or "default" to use whatever default your host has. Note that only multiples of 4 are usable as the two rightmost bits have been redefined for use by ECN (RFC 3168 section 23.1). The squid parser will enforce this by masking away the ECN bits. Processing proceeds in the order specified, and stops at first fully matching line. Only fast ACLs are supported. DOC_END NAME: clientside_tos TYPE: acl_tos DEFAULT: none LOC: Ip::Qos::TheConfig.tosToClient DOC_START Allows you to select a TOS/DSCP value for packets being transmitted on the client-side, based on an ACL. clientside_tos ds-field [!]aclname ... Example where normal_service_net uses the TOS value 0x00 and good_service_net uses 0x20 acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.1.0/24 clientside_tos 0x00 normal_service_net clientside_tos 0x20 good_service_net Note: This feature is incompatible with qos_flows. Any TOS values set here will be overwritten by TOS values in qos_flows. The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or "default" to use whatever default your host has. Note that only multiples of 4 are usable as the two rightmost bits have been redefined for use by ECN (RFC 3168 section 23.1). The squid parser will enforce this by masking away the ECN bits. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: tcp_outgoing_mark TYPE: acl_nfmark IFDEF: SO_MARK&&USE_LIBCAP DEFAULT: none LOC: Ip::Qos::TheConfig.nfmarkToServer DOC_START Allows you to apply a Netfilter mark value to outgoing packets on the server side, based on an ACL. tcp_outgoing_mark mark-value [!]aclname ... Example where normal_service_net uses the mark value 0x00 and good_service_net uses 0x20 acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.1.0/24 tcp_outgoing_mark 0x00 normal_service_net tcp_outgoing_mark 0x20 good_service_net Only fast ACLs are supported. DOC_END NAME: mark_client_packet clientside_mark TYPE: acl_nfmark IFDEF: SO_MARK&&USE_LIBCAP DEFAULT: none LOC: Ip::Qos::TheConfig.nfmarkToClient DOC_START Allows you to apply a Netfilter MARK value to packets being transmitted on the client-side, based on an ACL. mark_client_packet mark-value [!]aclname ... Example where normal_service_net uses the MARK value 0x00 and good_service_net uses 0x20 acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.1.0/24 mark_client_packet 0x00 normal_service_net mark_client_packet 0x20 good_service_net Note: This feature is incompatible with qos_flows. Any mark values set here will be overwritten by mark values in qos_flows. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: mark_client_connection TYPE: acl_nfmark IFDEF: SO_MARK&&USE_LIBCAP DEFAULT: none LOC: Ip::Qos::TheConfig.nfConnmarkToClient DOC_START Allows you to apply a Netfilter CONNMARK value to a connection on the client-side, based on an ACL. mark_client_connection mark-value[/mask] [!]aclname ... The mark-value and mask are unsigned integers (hex, octal, or decimal). The mask may be used to preserve marking previously set by other agents (e.g., iptables). A matching rule replaces the CONNMARK value. If a mask is also specified, then the masked bits of the original value are zeroed, and the configured mark-value is ORed with that adjusted value. For example, applying a mark-value 0xAB/0xF to 0x5F CONNMARK, results in a 0xFB marking (rather than a 0xAB or 0x5B). This directive semantics is similar to iptables --set-mark rather than --set-xmark functionality. The directive does not interfere with qos_flows (which uses packet MARKs, not CONNMARKs). Example where squid marks intercepted FTP connections: acl proto_ftp proto FTP mark_client_connection 0x200/0xff00 proto_ftp This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: qos_flows TYPE: QosConfig IFDEF: USE_QOS_TOS DEFAULT: none LOC: Ip::Qos::TheConfig DOC_START Allows you to select a TOS/DSCP value to mark outgoing connections to the client, based on where the reply was sourced. For platforms using netfilter, allows you to set a netfilter mark value instead of, or in addition to, a TOS value. By default this functionality is disabled. To enable it with the default settings simply use "qos_flows mark" or "qos_flows tos". Default settings will result in the netfilter mark or TOS value being copied from the upstream connection to the client. Note that it is the connection CONNMARK value not the packet MARK value that is copied. It is not currently possible to copy the mark or TOS value from the client to the upstream connection request. TOS values really only have local significance - so you should know what you're specifying. For more information, see RFC2474, RFC2475, and RFC3260. The TOS/DSCP byte must be exactly that - a octet value 0 - 255. Note that only multiples of 4 are usable as the two rightmost bits have been redefined for use by ECN (RFC 3168 section 23.1). The squid parser will enforce this by masking away the ECN bits. Mark values can be any unsigned 32-bit integer value. This setting is configured by setting the following values: tos|mark Whether to set TOS or netfilter mark values local-hit=0xFF Value to mark local cache hits. sibling-hit=0xFF Value to mark hits from sibling peers. parent-hit=0xFF Value to mark hits from parent peers. miss=0xFF[/mask] Value to mark cache misses. Takes precedence over the preserve-miss feature (see below), unless mask is specified, in which case only the bits specified in the mask are written. The TOS variant of the following features are only possible on Linux and require your kernel to be patched with the TOS preserving ZPH patch, available from http://zph.bratcheda.org No patch is needed to preserve the netfilter mark, which will work with all variants of netfilter. disable-preserve-miss This option disables the preservation of the TOS or netfilter mark. By default, the existing TOS or netfilter mark value of the response coming from the remote server will be retained and masked with miss-mark. NOTE: in the case of a netfilter mark, the mark must be set on the connection (using the CONNMARK target) not on the packet (MARK target). miss-mask=0xFF Allows you to mask certain bits in the TOS or mark value received from the remote server, before copying the value to the TOS sent towards clients. Default for tos: 0xFF (TOS from server is not changed). Default for mark: 0xFFFFFFFF (mark from server is not changed). All of these features require the --enable-zph-qos compilation flag (enabled by default). Netfilter marking also requires the libnetfilter_conntrack libraries (--with-netfilter-conntrack) and libcap 2.09+ (--with-libcap). DOC_END NAME: tcp_outgoing_address TYPE: acl_address DEFAULT: none DEFAULT_DOC: Address selection is performed by the operating system. LOC: Config.accessList.outgoing_address DOC_START Allows you to map requests to different outgoing IP addresses based on the username or source address of the user making the request. tcp_outgoing_address ipaddr [[!]aclname] ... For example; Forwarding clients with dedicated IPs for certain subnets. acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.2.0/24 tcp_outgoing_address 2001:db8::c001 good_service_net tcp_outgoing_address 10.1.0.2 good_service_net tcp_outgoing_address 2001:db8::beef normal_service_net tcp_outgoing_address 10.1.0.1 normal_service_net tcp_outgoing_address 2001:db8::1 tcp_outgoing_address 10.1.0.3 Processing proceeds in the order specified, and stops at first fully matching line. Squid will add an implicit IP version test to each line. Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses. Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses. NOTE: The use of this directive using client dependent ACLs is incompatible with the use of server side persistent connections. To ensure correct results it is best to set server_persistent_connections to off when using this directive in such configurations. NOTE: The use of this directive to set a local IP on outgoing TCP links is incompatible with using TPROXY to set client IP out outbound TCP links. When needing to contact peers use the no-tproxy cache_peer option and the client_dst_passthru directive re-enable normal forwarding such as this. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: host_verify_strict TYPE: onoff DEFAULT: off LOC: Config.onoff.hostStrictVerify DOC_START Regardless of this option setting, when dealing with intercepted traffic, Squid always verifies that the destination IP address matches the Host header domain or IP (called 'authority form URL'). This enforcement is performed to satisfy a MUST-level requirement in RFC 2616 section 14.23: "The Host field value MUST represent the naming authority of the origin server or gateway given by the original URL". When set to ON: Squid always responds with an HTTP 409 (Conflict) error page and logs a security warning if there is no match. Squid verifies that the destination IP address matches the Host header for forward-proxy and reverse-proxy traffic as well. For those traffic types, Squid also enables the following checks, comparing the corresponding Host header and Request-URI components: * The host names (domain or IP) must be identical, but valueless or missing Host header disables all checks. For the two host names to match, both must be either IP or FQDN. * Port numbers must be identical, but if a port is missing the scheme-default port is assumed. When set to OFF (the default): Squid allows suspicious requests to continue but logs a security warning and blocks caching of the response. * Forward-proxy traffic is not checked at all. * Reverse-proxy traffic is not checked at all. * Intercepted traffic which passes verification is handled according to client_dst_passthru. * Intercepted requests which fail verification are sent to the client original destination instead of DIRECT. This overrides 'client_dst_passthru off'. For now suspicious intercepted CONNECT requests are always responded to with an HTTP 409 (Conflict) error page. SECURITY NOTE: As described in CVE-2009-0801 when the Host: header alone is used to determine the destination of a request it becomes trivial for malicious scripts on remote websites to bypass browser same-origin security policy and sandboxing protections. The cause of this is that such applets are allowed to perform their own HTTP stack, in which case the same-origin policy of the browser sandbox only verifies that the applet tries to contact the same IP as from where it was loaded at the IP level. The Host: header may be different from the connected IP and approved origin. DOC_END NAME: client_dst_passthru TYPE: onoff DEFAULT: on LOC: Config.onoff.client_dst_passthru DOC_START With NAT or TPROXY intercepted traffic Squid may pass the request directly to the original client destination IP or seek a faster source using the HTTP Host header. Using Host to locate alternative servers can provide faster connectivity with a range of failure recovery options. But can also lead to connectivity trouble when the client and server are attempting stateful interactions unaware of the proxy. This option (on by default) prevents alternative DNS entries being located to send intercepted traffic DIRECT to an origin server. The clients original destination IP and port will be used instead. Regardless of this option setting, when dealing with intercepted traffic Squid will verify the Host: header and any traffic which fails Host verification will be treated as if this option were ON. see host_verify_strict for details on the verification process. DOC_END COMMENT_START TLS OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: tls_outgoing_options IFDEF: USE_GNUTLS||USE_OPENSSL TYPE: securePeerOptions DEFAULT: min-version=1.0 LOC: Security::ProxyOutgoingConfig DOC_START disable Do not support https:// URLs. cert=/path/to/client/certificate A client X.509 certificate to use when connecting. key=/path/to/client/private_key The private key corresponding to the cert= above. If key= is not specified cert= is assumed to reference a PEM file containing both the certificate and private key. cipher=... The list of valid TLS ciphers to use. min-version=1.N The minimum TLS protocol version to permit. To control SSLv3 use the options= parameter. Supported Values: 1.0 (default), 1.1, 1.2, 1.3 options=... Specify various TLS/SSL implementation options. OpenSSL options most important are: NO_SSLv3 Disallow the use of SSLv3 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges NO_TICKET Disable use of RFC5077 session tickets. Some servers may have problems understanding the TLS extension due to ambiguous specification in RFC4507. ALL Enable various bug workarounds suggested as "harmless" by OpenSSL Be warned that this reduces SSL/TLS strength to some attacks. See the OpenSSL SSL_CTX_set_options documentation for a more complete list. GnuTLS options most important are: %NO_TICKETS Disable use of RFC5077 session tickets. Some servers may have problems understanding the TLS extension due to ambiguous specification in RFC4507. See the GnuTLS Priority Strings documentation for a more complete list. http://www.gnutls.org/manual/gnutls.html#Priority-Strings cafile= PEM file containing CA certificates to use when verifying the peer certificate. May be repeated to load multiple files. capath= A directory containing additional CA certificates to use when verifying the peer certificate. Requires OpenSSL or LibreSSL. crlfile=... A certificate revocation list file to use when verifying the peer certificate. flags=... Specify various flags modifying the TLS implementation: DONT_VERIFY_PEER Accept certificates even if they fail to verify. DONT_VERIFY_DOMAIN Don't verify the peer certificate matches the server name default-ca[=off] Whether to use the system Trusted CAs. Default is ON. domain= The peer name as advertised in its certificate. Used for verifying the correctness of the received peer certificate. If not specified the peer hostname will be used. DOC_END COMMENT_START SSL OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: ssl_unclean_shutdown IFDEF: USE_OPENSSL TYPE: onoff DEFAULT: off LOC: Config.SSL.unclean_shutdown DOC_START Some browsers (especially MSIE) bugs out on SSL shutdown messages. DOC_END NAME: ssl_engine IFDEF: USE_OPENSSL TYPE: string LOC: Config.SSL.ssl_engine DEFAULT: none DOC_START The OpenSSL engine to use. You will need to set this if you would like to use hardware SSL acceleration for example. Not supported in builds with OpenSSL 3.0 or newer. DOC_END NAME: sslproxy_session_ttl IFDEF: USE_OPENSSL DEFAULT: 300 LOC: Config.SSL.session_ttl TYPE: int DOC_START Sets the timeout value for SSL sessions DOC_END NAME: sslproxy_session_cache_size IFDEF: USE_OPENSSL DEFAULT: 2 MB LOC: Config.SSL.sessionCacheSize TYPE: b_size_t DOC_START Sets the cache size to use for ssl session DOC_END NAME: sslproxy_foreign_intermediate_certs IFDEF: USE_OPENSSL DEFAULT: none LOC: Config.ssl_client.foreignIntermediateCertsPath TYPE: string DOC_START Many origin servers fail to send their full server certificate chain for verification, assuming the client already has or can easily locate any missing intermediate certificates. Squid uses the certificates from the specified file to fill in these missing chains when trying to validate origin server certificate chains. The file is expected to contain zero or more PEM-encoded intermediate certificates. These certificates are not treated as trusted root certificates, and any self-signed certificate in this file will be ignored. DOC_END NAME: sslproxy_cert_sign_hash IFDEF: USE_OPENSSL DEFAULT: none LOC: Config.SSL.certSignHash TYPE: string DOC_START Sets the hashing algorithm to use when signing generated certificates. Valid algorithm names depend on the OpenSSL library used. The following names are usually available: sha1, sha256, sha512, and md5. Please see your OpenSSL library manual for the available hashes. By default, Squids that support this option use sha256 hashes. Squid does not forcefully purge cached certificates that were generated with an algorithm other than the currently configured one. They remain in the cache, subject to the regular cache eviction policy, and become useful if the algorithm changes again. DOC_END NAME: ssl_bump IFDEF: USE_OPENSSL TYPE: sslproxy_ssl_bump LOC: Config.accessList.ssl_bump DEFAULT_DOC: Become a TCP tunnel without decrypting proxied traffic. DEFAULT: none DOC_START This option is consulted when a CONNECT request is received on an http_port (or a new connection is intercepted at an https_port), provided that port was configured with an ssl-bump flag. The subsequent data on the connection is either treated as HTTPS and decrypted OR tunneled at TCP level without decryption, depending on the first matching bumping "action". ssl_bump [!]acl ... The following bumping actions are currently supported: splice Become a TCP tunnel without decrypting proxied traffic. This is the default action. bump When used on step SslBump1, establishes a secure connection with the client first, then connect to the server. When used on step SslBump2 or SslBump3, establishes a secure connection with the server and, using a mimicked server certificate, with the client. peek Receive client (step SslBump1) or server (step SslBump2) certificate while preserving the possibility of splicing the connection. Peeking at the server certificate (during step 2) usually precludes bumping of the connection at step 3. stare Receive client (step SslBump1) or server (step SslBump2) certificate while preserving the possibility of bumping the connection. Staring at the server certificate (during step 2) usually precludes splicing of the connection at step 3. terminate Close client and server connections. Backward compatibility actions available at step SslBump1: client-first Bump the connection. Establish a secure connection with the client first, then connect to the server. This old mode does not allow Squid to mimic server SSL certificate and does not work with intercepted SSL connections. server-first Bump the connection. Establish a secure connection with the server first, then establish a secure connection with the client, using a mimicked server certificate. Works with both CONNECT requests and intercepted SSL connections, but does not allow to make decisions based on SSL handshake info. peek-and-splice Decide whether to bump or splice the connection based on client-to-squid and server-to-squid SSL hello messages. XXX: Remove. none Same as the "splice" action. All ssl_bump rules are evaluated at each of the supported bumping steps. Rules with actions that are impossible at the current step are ignored. The first matching ssl_bump action wins and is applied at the end of the current step. If no rules match, the splice action is used. See the at_step ACL for a list of the supported SslBump steps. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. See also: http_port ssl-bump, https_port ssl-bump, and acl at_step. # Example: Bump all TLS connections except those originating from # localhost or those going to example.com. acl broken_sites ssl::server_name .example.com ssl_bump splice localhost ssl_bump splice broken_sites ssl_bump bump all DOC_END NAME: sslproxy_cert_error IFDEF: USE_OPENSSL DEFAULT: none DEFAULT_DOC: Server certificate errors terminate the transaction. LOC: Config.ssl_client.cert_error TYPE: acl_access DOC_START Use this ACL to bypass server certificate validation errors. For example, the following lines will bypass all validation errors when talking to servers for example.com. All other validation errors will result in ERR_SECURE_CONNECT_FAIL error. acl BrokenButTrustedServers dstdomain example.com sslproxy_cert_error allow BrokenButTrustedServers sslproxy_cert_error deny all This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Using slow acl types may result in server crashes Without this option, all server certificate validation errors terminate the transaction to protect Squid and the client. SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed but should not happen unless your OpenSSL library is buggy. SECURITY WARNING: Bypassing validation errors is dangerous because an error usually implies that the server cannot be trusted and the connection may be insecure. See also: sslproxy_flags and DONT_VERIFY_PEER. DOC_END NAME: sslproxy_cert_sign IFDEF: USE_OPENSSL DEFAULT: none POSTSCRIPTUM: signUntrusted ssl::certUntrusted POSTSCRIPTUM: signSelf ssl::certSelfSigned POSTSCRIPTUM: signTrusted all TYPE: sslproxy_cert_sign LOC: Config.ssl_client.cert_sign DOC_START sslproxy_cert_sign acl ... The following certificate signing algorithms are supported: signTrusted Sign using the configured CA certificate which is usually placed in and trusted by end-user browsers. This is the default for trusted origin server certificates. signUntrusted Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error. This is the default for untrusted origin server certificates that are not self-signed (see ssl::certUntrusted). signSelf Sign using a self-signed certificate with the right CN to generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the browser. This is the default for self-signed origin server certificates (see ssl::certSelfSigned). This clause only supports fast acl types. When sslproxy_cert_sign acl(s) match, Squid uses the corresponding signing algorithm to generate the certificate and ignores all subsequent sslproxy_cert_sign options (the first match wins). If no acl(s) match, the default signing algorithm is determined by errors detected when obtaining and validating the origin server certificate. WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can be used with sslproxy_cert_adapt, but if and only if Squid is bumping a CONNECT request that carries a domain name. In all other cases (CONNECT to an IP address or an intercepted SSL connection), Squid cannot detect the domain mismatch at certificate generation time when bump-server-first is used. DOC_END NAME: sslproxy_cert_adapt IFDEF: USE_OPENSSL DEFAULT: none TYPE: sslproxy_cert_adapt LOC: Config.ssl_client.cert_adapt DOC_START sslproxy_cert_adapt acl ... The following certificate adaptation algorithms are supported: setValidAfter Sets the "Not After" property to the "Not After" property of the CA certificate used to sign generated certificates. setValidBefore Sets the "Not Before" property to the "Not Before" property of the CA certificate used to sign generated certificates. setCommonName or setCommonName{CN} Sets Subject.CN property to the host name specified as a CN parameter or, if no explicit CN parameter was specified, extracted from the CONNECT request. It is a misconfiguration to use setCommonName without an explicit parameter for intercepted or tproxied SSL connections. This clause only supports fast acl types. Squid first groups sslproxy_cert_adapt options by adaptation algorithm. Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the corresponding adaptation algorithm to generate the certificate and ignores all subsequent sslproxy_cert_adapt options in that algorithm's group (i.e., the first match wins within each algorithm group). If no acl(s) match, the default mimicking action takes place. WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can be used with sslproxy_cert_adapt, but if and only if Squid is bumping a CONNECT request that carries a domain name. In all other cases (CONNECT to an IP address or an intercepted SSL connection), Squid cannot detect the domain mismatch at certificate generation time when bump-server-first is used. DOC_END NAME: sslpassword_program IFDEF: USE_OPENSSL DEFAULT: none LOC: Config.Program.ssl_password TYPE: string DOC_START Specify a program used for entering SSL key passphrases when using encrypted SSL certificate keys. If not specified keys must either be unencrypted, or Squid started with the -N option to allow it to query interactively for the passphrase. The key file name is given as argument to the program allowing selection of the right password if you have multiple encrypted keys. DOC_END COMMENT_START OPTIONS RELATING TO EXTERNAL SSL_CRTD ----------------------------------------------------------------------------- COMMENT_END NAME: sslcrtd_program TYPE: eol IFDEF: USE_SSL_CRTD DEFAULT: @DEFAULT_SSL_CRTD@ -s @DEFAULT_SSL_DB_DIR@ -M 4MB LOC: Ssl::TheConfig.ssl_crtd DOC_START Specify the location and options of the executable for certificate generator. @DEFAULT_SSL_CRTD@ program can use a disk cache to improve response times on repeated requests. To enable caching, specify -s and -M parameters. If those parameters are not given, the program generates a new certificate on every request. For more information use: @DEFAULT_SSL_CRTD@ -h DOC_END NAME: sslcrtd_children TYPE: HelperChildConfig IFDEF: USE_SSL_CRTD DEFAULT: 32 startup=5 idle=1 LOC: Ssl::TheConfig.ssl_crtdChildren DOC_START Specifies the maximum number of certificate generation processes that Squid may spawn (numberofchildren) and several related options. Using too few of these helper processes (a.k.a. "helpers") creates request queues. Using too many helpers wastes your system resources. Squid does not support spawning more than 32 helpers. Usage: numberofchildren [option]... The startup= and idle= options allow some measure of skew in your tuning. startup=N Sets the minimum number of processes to spawn when Squid starts or reconfigures. When set to zero the first request will cause spawning of the first child process to handle it. Starting too few children temporary slows Squid under load while it tries to spawn enough additional processes to cope with traffic. idle=N Sets a minimum of how many processes Squid is to try and keep available at all times. When traffic begins to rise above what the existing processes can handle this many more will be spawned up to the maximum configured. A minimum setting of 1 is required. queue-size=N Sets the maximum number of queued requests. A request is queued when no existing child is idle and no new child can be started due to numberofchildren limit. If the queued requests exceed queue size for more than 3 minutes squid aborts its operation. The default value is set to 2*numberofchildren. You must have at least one ssl_crtd process. DOC_END NAME: sslcrtvalidator_program TYPE: eol IFDEF: USE_OPENSSL DEFAULT: none LOC: Ssl::TheConfig.ssl_crt_validator DOC_START Specify the location and options of the executable for ssl_crt_validator process. Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ... Options: ttl=n TTL in seconds for cached results. The default is 60 secs cache=n limit the result cache size. The default value is 2048 DOC_END NAME: sslcrtvalidator_children TYPE: HelperChildConfig IFDEF: USE_OPENSSL DEFAULT: 32 startup=5 idle=1 concurrency=1 LOC: Ssl::TheConfig.ssl_crt_validator_Children DOC_START Specifies the maximum number of certificate validation processes that Squid may spawn (numberofchildren) and several related options. Using too few of these helper processes (a.k.a. "helpers") creates request queues. Using too many helpers wastes your system resources. Squid does not support spawning more than 32 helpers. Usage: numberofchildren [option]... The startup= and idle= options allow some measure of skew in your tuning. startup=N Sets the minimum number of processes to spawn when Squid starts or reconfigures. When set to zero the first request will cause spawning of the first child process to handle it. Starting too few children temporary slows Squid under load while it tries to spawn enough additional processes to cope with traffic. idle=N Sets a minimum of how many processes Squid is to try and keep available at all times. When traffic begins to rise above what the existing processes can handle this many more will be spawned up to the maximum configured. A minimum setting of 1 is required. concurrency= The number of requests each certificate validator helper can handle in parallel. A value of 0 indicates the certficate validator does not support concurrency. Defaults to 1. When this directive is set to a value >= 1 then the protocol used to communicate with the helper is modified to include a request ID in front of the request/response. The request ID from the request must be echoed back with the response to that request. queue-size=N Sets the maximum number of queued requests. A request is queued when no existing child can accept it due to concurrency limit and no new child can be started due to numberofchildren limit. If the queued requests exceed queue size for more than 3 minutes squid aborts its operation. The default value is set to 2*numberofchildren. You must have at least one ssl_crt_validator process. DOC_END COMMENT_START OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM ----------------------------------------------------------------------------- COMMENT_END NAME: cache_peer TYPE: peer DEFAULT: none LOC: Config.peers DOC_START To specify other caches in a hierarchy, use the format: cache_peer hostname type http-port icp-port [options] For example, # proxy icp # hostname type port port options # -------------------- -------- ----- ----- ----------- cache_peer parent.foo.net parent 3128 3130 default cache_peer sib1.foo.net sibling 3128 3130 proxy-only cache_peer sib2.foo.net sibling 3128 3130 proxy-only cache_peer example.com parent 80 0 default cache_peer cdn.example.com sibling 3128 0 type: either 'parent', 'sibling', or 'multicast'. proxy-port: The port number where the peer accept HTTP requests. For other Squid proxies this is usually 3128 For web servers this is usually 80 icp-port: Used for querying neighbor caches about objects. Set to 0 if the peer does not support ICP or HTCP. See ICP and HTCP options below for additional details. ==== ICP OPTIONS ==== You MUST also set icp_port and icp_access explicitly when using these options. The defaults will prevent peer traffic using ICP. no-query Disable ICP queries to this neighbor. multicast-responder Indicates the named peer is a member of a multicast group. ICP queries will not be sent directly to the peer, but ICP replies will be accepted from it. closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes. background-ping To only send ICP queries to this neighbor infrequently. This is used to keep the neighbor round trip time updated and is usually used in conjunction with weighted-round-robin. ==== HTCP OPTIONS ==== You MUST also set htcp_port and htcp_access explicitly when using these options. The defaults will prevent peer traffic using HTCP. htcp Send HTCP, instead of ICP, queries to the neighbor. You probably also want to set the "icp-port" to 4827 instead of 3130. This directive accepts a comma separated list of options described below. htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier). htcp=no-clr Send HTCP to the neighbor but without sending any CLR requests. This cannot be used with only-clr. htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests. This cannot be used with no-clr. htcp=no-purge-clr Send HTCP to the neighbor including CLRs but only when they do not result from PURGE requests. htcp=forward-clr Forward any HTCP CLR requests this proxy receives to the peer. ==== PEER SELECTION METHODS ==== The default peer selection method is ICP, with the first responding peer being used as source. These options can be used for better load balancing. default This is a parent cache which can be used as a "last-resort" if a peer cannot be located by any of the peer-selection methods. If specified more than once, only the first is used. round-robin Load-Balance parents which should be used in a round-robin fashion in the absence of any ICP queries. weight=N can be used to add bias. weighted-round-robin Load-Balance parents which should be used in a round-robin fashion with the frequency of each parent being based on the round trip time. Closer parents are used more often. Usually used for background-ping parents. weight=N can be used to add bias. carp Load-Balance parents which should be used as a CARP array. The requests will be distributed among the parents based on the CARP load balancing hash function based on their weight. userhash Load-balance parents based on the client proxy_auth or ident username. sourcehash Load-balance parents based on the client source IP. multicast-siblings To be used only for cache peers of type "multicast". ALL members of this multicast group have "sibling" relationship with it, not "parent". This is to a multicast group when the requested object would be fetched only from a "parent" cache, anyway. It's useful, e.g., when configuring a pool of redundant Squid proxies, being members of the same multicast group. ==== PEER SELECTION OPTIONS ==== weight=N use to affect the selection of a peer during any weighted peer-selection mechanisms. The weight must be an integer; default is 1, larger weights are favored more. This option does not affect parent selection if a peering protocol is not in use. basetime=N Specify a base amount to be subtracted from round trip times of parents. It is subtracted before division by weight in calculating which parent to fectch from. If the rtt is less than the base time the rtt is set to a minimal value. ttl=N Specify a TTL to use when sending multicast ICP queries to this address. Only useful when sending to a multicast group. Because we don't accept ICP replies from random hosts, you must configure other group members as peers with the 'multicast-responder' option. no-delay To prevent access to this neighbor from influencing the delay pools. digest-url=URL Tell Squid to fetch the cache digest (if digests are enabled) for this host from the specified URL rather than the Squid default location. ==== CARP OPTIONS ==== carp-key=key-specification use a different key than the full URL to hash against the peer. the key-specification is a comma-separated list of the keywords scheme, host, port, path, params Order is not important. ==== ACCELERATOR / REVERSE-PROXY OPTIONS ==== originserver Causes this parent to be contacted as an origin server. Meant to be used in accelerator setups when the peer is a web server. forceddomain=name Set the Host header of requests forwarded to this peer. Useful in accelerator setups where the server (peer) expects a certain domain name but clients may request others. ie example.com or www.example.com no-digest Disable request of cache digests. no-netdb-exchange Disables requesting ICMP RTT database (NetDB). ==== AUTHENTICATION OPTIONS ==== login=user:password If this is a personal/workgroup proxy and your parent requires proxy authentication. Note: The string can include URL escapes (i.e. %20 for spaces). This also means % must be written as %%. login=PASSTHRU Send login details received from client to this peer. Both Proxy- and WWW-Authorization headers are passed without alteration to the peer. Authentication is not required by Squid for this to work. Note: This will pass any form of authentication but only Basic auth will work through a proxy unless the connection-auth options are also used. login=PASS Send login details received from client to this peer. Authentication is not required by this option. If there are no client-provided authentication headers to pass on, but username and password are available from an external ACL user= and password= result tags they may be sent instead. Note: To combine this with proxy_auth both proxies must share the same user database as HTTP only allows for a single login (one for proxy, one for origin server). Also be warned this will expose your users proxy password to the peer. USE WITH CAUTION login=*:password Send the username to the upstream cache, but with a fixed password. This is meant to be used when the peer is in another administrative domain, but it is still needed to identify each user. The star can optionally be followed by some extra information which is added to the username. This can be used to identify this proxy to the peer, similar to the login=username:password option above. login=NEGOTIATE If this is a personal/workgroup proxy and your parent requires a secure proxy authentication. The first principal from the default keytab or defined by the environment variable KRB5_KTNAME will be used. WARNING: The connection may transmit requests from multiple clients. Negotiate often assumes end-to-end authentication and a single-client. Which is not strictly true here. login=NEGOTIATE:principal_name If this is a personal/workgroup proxy and your parent requires a secure proxy authentication. The principal principal_name from the default keytab or defined by the environment variable KRB5_KTNAME will be used. WARNING: The connection may transmit requests from multiple clients. Negotiate often assumes end-to-end authentication and a single-client. Which is not strictly true here. connection-auth=on|off Tell Squid that this peer does or not support Microsoft connection oriented authentication, and any such challenges received from there should be ignored. Default is auto to automatically determine the status of the peer. auth-no-keytab Do not use a keytab to authenticate to a peer when login=NEGOTIATE is specified. Let the GSSAPI implementation determine which already existing credentials cache to use instead. ==== SSL / HTTPS / TLS OPTIONS ==== tls Encrypt connections to this peer with TLS. sslcert=/path/to/ssl/certificate A client X.509 certificate to use when connecting to this peer. sslkey=/path/to/ssl/key The private key corresponding to sslcert above. If sslkey= is not specified sslcert= is assumed to reference a PEM file containing both the certificate and private key. sslcipher=... The list of valid SSL ciphers to use when connecting to this peer. tls-min-version=1.N The minimum TLS protocol version to permit. To control SSLv3 use the tls-options= parameter. Supported Values: 1.0 (default), 1.1, 1.2 tls-options=... Specify various TLS implementation options. OpenSSL options most important are: NO_SSLv3 Disallow the use of SSLv3 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges NO_TICKET Disable use of RFC5077 session tickets. Some servers may have problems understanding the TLS extension due to ambiguous specification in RFC4507. ALL Enable various bug workarounds suggested as "harmless" by OpenSSL Be warned that this reduces SSL/TLS strength to some attacks. See the OpenSSL SSL_CTX_set_options documentation for a more complete list. GnuTLS options most important are: %NO_TICKETS Disable use of RFC5077 session tickets. Some servers may have problems understanding the TLS extension due to ambiguous specification in RFC4507. See the GnuTLS Priority Strings documentation for a more complete list. http://www.gnutls.org/manual/gnutls.html#Priority-Strings tls-cafile= PEM file containing CA certificates to use when verifying the peer certificate. May be repeated to load multiple files. sslcapath=... A directory containing additional CA certificates to use when verifying the peer certificate. Requires OpenSSL or LibreSSL. sslcrlfile=... A certificate revocation list file to use when verifying the peer certificate. sslflags=... Specify various flags modifying the SSL implementation: DONT_VERIFY_PEER Accept certificates even if they fail to verify. DONT_VERIFY_DOMAIN Don't verify the peer certificate matches the server name ssldomain= The peer name as advertised in it's certificate. Used for verifying the correctness of the received peer certificate. If not specified the peer hostname will be used. front-end-https[=off|on|auto] Enable the "Front-End-Https: On" header needed when using Squid as a SSL frontend in front of Microsoft OWA. See MS KB document Q307347 for details on this header. If set to auto the header will only be added if the request is forwarded as a https:// URL. tls-default-ca[=off] Whether to use the system Trusted CAs. Default is ON. tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1. ==== GENERAL OPTIONS ==== connect-timeout=N A peer-specific connect timeout. Also see the peer_connect_timeout directive. connect-fail-limit=N How many times connecting to a peer must fail before it is marked as down. Standby connection failures count towards this limit. Default is 10. allow-miss Disable Squid's use of only-if-cached when forwarding requests to siblings. This is primarily useful when icp_hit_stale is used by the sibling. Excessive use of this option may result in forwarding loops. One way to prevent peering loops when using this option, is to deny cache peer usage on requests from a peer: acl fromPeer ... cache_peer_access peerName deny fromPeer max-conn=N Limit the number of concurrent connections the Squid may open to this peer, including already opened idle and standby connections. There is no peer-specific connection limit by default. A peer exceeding the limit is not used for new requests unless a standby connection is available. max-conn currently works poorly with idle persistent connections: When a peer reaches its max-conn limit, and there are idle persistent connections to the peer, the peer may not be selected because the limiting code does not know whether Squid can reuse those idle connections. standby=N Maintain a pool of N "hot standby" connections to an UP peer, available for requests when no idle persistent connection is available (or safe) to use. By default and with zero N, no such pool is maintained. N must not exceed the max-conn limit (if any). At start or after reconfiguration, Squid opens new TCP standby connections until there are N connections available and then replenishes the standby pool as opened connections are used up for requests. A used connection never goes back to the standby pool, but may go to the regular idle persistent connection pool shared by all peers and origin servers. Squid never opens multiple new standby connections concurrently. This one-at-a-time approach minimizes flooding-like effect on peers. Furthermore, just a few standby connections should be sufficient in most cases to supply most new requests with a ready-to-use connection. Standby connections obey server_idle_pconn_timeout. For the feature to work as intended, the peer must be configured to accept and keep them open longer than the idle timeout at the connecting Squid, to minimize race conditions typical to idle used persistent connections. Default request_timeout and server_idle_pconn_timeout values ensure such a configuration. name=xxx Unique name for the peer. Required if you have multiple peers on the same host but different ports. This name can be used in cache_peer_access and similar directives to identify the peer. Can be used by outgoing access controls through the peername ACL type. no-tproxy Do not use the client-spoof TPROXY support when forwarding requests to this peer. Use normal address selection instead. This overrides the spoof_client_ip ACL. proxy-only objects fetched from the peer will not be stored locally. DOC_END NAME: cache_peer_access TYPE: peer_access DEFAULT: none DEFAULT_DOC: No peer usage restrictions. LOC: none DOC_START Restricts usage of cache_peer proxies. Usage: cache_peer_access peer-name allow|deny [!]aclname ... For the required peer-name parameter, use either the value of the cache_peer name=value parameter or, if name=value is missing, the cache_peer hostname parameter. This directive narrows down the selection of peering candidates, but does not determine the order in which the selected candidates are contacted. That order is determined by the peer selection algorithms (see PEER SELECTION sections in the cache_peer documentation). If a deny rule matches, the corresponding peer will not be contacted for the current transaction -- Squid will not send ICP queries and will not forward HTTP requests to that peer. An allow match leaves the corresponding peer in the selection. The first match for a given peer wins for that peer. The relative order of cache_peer_access directives for the same peer matters. The relative order of any two cache_peer_access directives for different peers does not matter. To ease interpretation, it is a good idea to group cache_peer_access directives for the same peer together. A single cache_peer_access directive may be evaluated multiple times for a given transaction because individual peer selection algorithms may check it independently from each other. These redundant checks may be optimized away in future Squid versions. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: neighbor_type_domain TYPE: hostdomaintype DEFAULT: none DEFAULT_DOC: The peer type from cache_peer directive is used for all requests to that peer. LOC: none DOC_START Modify the cache_peer neighbor type when passing requests about specific domains to the peer. Usage: neighbor_type_domain neighbor parent|sibling domain domain ... For example: cache_peer foo.example.com parent 3128 3130 neighbor_type_domain foo.example.com sibling .au .de The above configuration treats all requests to foo.example.com as a parent proxy unless the request is for a .au or .de ccTLD domain name. DOC_END NAME: dead_peer_timeout COMMENT: (seconds) DEFAULT: 10 seconds TYPE: time_t LOC: Config.Timeout.deadPeer DOC_START This controls how long Squid waits to declare a peer cache as "dead." If there are no ICP replies received in this amount of time, Squid will declare the peer dead and not expect to receive any further ICP replies. However, it continues to send ICP queries, and will mark the peer as alive upon receipt of the first subsequent ICP reply. This timeout also affects when Squid expects to receive ICP replies from peers. If more than 'dead_peer' seconds have passed since the last ICP reply was received, Squid will not expect to receive an ICP reply on the next query. Thus, if your time between requests is greater than this timeout, you will see a lot of requests sent DIRECT to origin servers instead of to your parents. DOC_END NAME: forward_max_tries DEFAULT: 25 TYPE: int LOC: Config.forward_max_tries DOC_START Limits the number of attempts to forward the request. For the purpose of this limit, Squid counts all high-level request forwarding attempts, including any same-destination retries after certain persistent connection failures and any attempts to use a different peer. However, these low-level attempts are not counted: * connection reopening attempts (enabled using connect_retries) * unfinished Happy Eyeballs connection attempts (prevented by setting happy_eyeballs_connect_limit to 0) See also: forward_timeout and connect_retries. DOC_END COMMENT_START MEMORY CACHE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: cache_mem COMMENT: (bytes) TYPE: b_size_t DEFAULT: 256 MB LOC: Config.memMaxSize DOC_START NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE. IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS. 'cache_mem' specifies the ideal amount of memory to be used for: * In-Transit objects * Hot Objects * Negative-Cached objects Data for these objects are stored in 4 KB blocks. This parameter specifies the ideal upper limit on the total size of 4 KB blocks allocated. In-Transit objects take the highest priority. In-transit objects have priority over the others. When additional space is needed for incoming data, negative-cached and hot objects will be released. In other words, the negative-cached and hot objects will fill up any unused space not needed for in-transit objects. If circumstances require, this limit will be exceeded. Specifically, if your incoming request rate requires more than 'cache_mem' of memory to hold in-transit objects, Squid will exceed this limit to satisfy the new requests. When the load decreases, blocks will be freed until the high-water mark is reached. Thereafter, blocks will be used to store hot objects. If shared memory caching is enabled, Squid does not use the shared cache space for in-transit objects, but they still consume as much local memory as they need. For more details about the shared memory cache, see memory_cache_shared. DOC_END NAME: maximum_object_size_in_memory COMMENT: (bytes) TYPE: b_size_t DEFAULT: 512 KB LOC: Config.Store.maxInMemObjSize DOC_START Objects greater than this size will not be attempted to kept in the memory cache. This should be set high enough to keep objects accessed frequently in memory to improve performance whilst low enough to keep larger objects from hoarding cache_mem. DOC_END NAME: memory_cache_shared COMMENT: on|off TYPE: YesNoNone LOC: Config.memShared DEFAULT: none DEFAULT_DOC: "on" where supported if doing memory caching with multiple SMP workers. DOC_START Controls whether the memory cache is shared among SMP workers. The shared memory cache is meant to occupy cache_mem bytes and replace the non-shared memory cache, although some entities may still be cached locally by workers for now (e.g., internal and in-transit objects may be served from a local memory cache even if shared memory caching is enabled). By default, the memory cache is shared if and only if all of the following conditions are satisfied: Squid runs in SMP mode with multiple workers, cache_mem is positive, and Squid environment supports required IPC primitives (e.g., POSIX shared memory segments and GCC-style atomic operations). To avoid blocking locks, shared memory uses opportunistic algorithms that do not guarantee that every cachable entity that could have been shared among SMP workers will actually be shared. DOC_END NAME: memory_cache_mode TYPE: memcachemode LOC: Config DEFAULT: always DEFAULT_DOC: Keep the most recently fetched objects in memory DOC_START Controls which objects to keep in the memory cache (cache_mem) always Keep most recently fetched objects in memory (default) disk Only disk cache hits are kept in memory, which means an object must first be cached on disk and then hit a second time before cached in memory. network Only objects fetched from network is kept in memory DOC_END NAME: memory_replacement_policy TYPE: removalpolicy LOC: Config.memPolicy DEFAULT: lru DOC_START The memory replacement policy parameter determines which objects are purged from memory when memory space is needed. See cache_replacement_policy for details on algorithms. DOC_END COMMENT_START DISK CACHE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: cache_replacement_policy TYPE: removalpolicy LOC: Config.replPolicy DEFAULT: lru DOC_START The cache replacement policy parameter determines which objects are evicted (replaced) when disk space is needed. lru : Squid's original list based LRU policy heap GDSF : Greedy-Dual Size Frequency heap LFUDA: Least Frequently Used with Dynamic Aging heap LRU : LRU policy implemented using a heap Applies to any cache_dir lines listed below this directive. The LRU policies keeps recently referenced objects. The heap GDSF policy optimizes object hit rate by keeping smaller popular objects in cache so it has a better chance of getting a hit. It achieves a lower byte hit rate than LFUDA though since it evicts larger (possibly popular) objects. The heap LFUDA policy keeps popular objects in cache regardless of their size and thus optimizes byte hit rate at the expense of hit rate since one large, popular object will prevent many smaller, slightly less popular objects from being cached. Both policies utilize a dynamic aging mechanism that prevents cache pollution that can otherwise occur with frequency-based replacement policies. NOTE: if using the LFUDA replacement policy you should increase the value of maximum_object_size above its default of 4 MB to to maximize the potential byte hit rate improvement of LFUDA. For more information about the GDSF and LFUDA cache replacement policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html. DOC_END NAME: minimum_object_size COMMENT: (bytes) TYPE: b_int64_t DEFAULT: 0 KB DEFAULT_DOC: no limit LOC: Config.Store.minObjectSize DOC_START Objects smaller than this size will NOT be saved on disk. The value is specified in bytes, and the default is 0 KB, which means all responses can be stored. DOC_END NAME: maximum_object_size COMMENT: (bytes) TYPE: b_int64_t DEFAULT: 4 MB LOC: Config.Store.maxObjectSize DOC_START Set the default value for max-size parameter on any cache_dir. The value is specified in bytes, and the default is 4 MB. If you wish to get a high BYTES hit ratio, you should probably increase this (one 32 MB object hit counts for 3200 10KB hits). If you wish to increase hit ratio more than you want to save bandwidth you should leave this low. NOTE: if using the LFUDA replacement policy you should increase this value to maximize the byte hit rate improvement of LFUDA! See cache_replacement_policy for a discussion of this policy. DOC_END NAME: cache_dir TYPE: cachedir DEFAULT: none DEFAULT_DOC: No disk cache. Store cache ojects only in memory. LOC: Config.cacheSwap DOC_START Format: cache_dir Type Directory-Name Fs-specific-data [options] You can specify multiple cache_dir lines to spread the cache among different disk partitions. Type specifies the kind of storage system to use. Only "ufs" is built by default. To enable any of the other storage systems see the --enable-storeio configure option. 'Directory' is a top-level directory where cache swap files will be stored. If you want to use an entire disk for caching, this can be the mount-point directory. The directory must exist and be writable by the Squid process. Squid will NOT create this directory for you. In SMP configurations, cache_dir must not precede the workers option and should use configuration macros or conditionals to give each worker interested in disk caching a dedicated cache directory. ==== The ufs store type ==== "ufs" is the old well-known Squid storage format that has always been there. Usage: cache_dir ufs Directory-Name Mbytes L1 L2 [options] 'Mbytes' is the amount of disk space (MB) to use under this directory. The default is 100 MB. Change this to suit your configuration. Do NOT put the size of your disk drive here. Instead, if you want Squid to use the entire disk drive, subtract 20% and use that value. 'L1' is the number of first-level subdirectories which will be created under the 'Directory'. The default is 16. 'L2' is the number of second-level subdirectories which will be created under each first-level directory. The default is 256. ==== The aufs store type ==== "aufs" uses the same storage format as "ufs", utilizing POSIX-threads to avoid blocking the main Squid process on disk-I/O. This was formerly known in Squid as async-io. Usage: cache_dir aufs Directory-Name Mbytes L1 L2 [options] see argument descriptions under ufs above ==== The diskd store type ==== "diskd" uses the same storage format as "ufs", utilizing a separate process to avoid blocking the main Squid process on disk-I/O. Usage: cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n] see argument descriptions under ufs above Q1 specifies the number of unacknowledged I/O requests when Squid stops opening new files. If this many messages are in the queues, Squid won't open new files. Default is 64 Q2 specifies the number of unacknowledged messages when Squid starts blocking. If this many messages are in the queues, Squid blocks until it receives some replies. Default is 72 When Q1 < Q2 (the default), the cache directory is optimized for lower response time at the expense of a decrease in hit ratio. If Q1 > Q2, the cache directory is optimized for higher hit ratio at the expense of an increase in response time. ==== The rock store type ==== Usage: cache_dir rock Directory-Name Mbytes [options] The Rock Store type is a database-style storage. All cached entries are stored in a "database" file, using fixed-size slots. A single entry occupies one or more slots. If possible, Squid using Rock Store creates a dedicated kid process called "disker" to avoid blocking Squid worker(s) on disk I/O. One disker kid is created for each rock cache_dir. Diskers are created only when Squid, running in daemon mode, has support for the IpcIo disk I/O module. swap-timeout=msec: Squid will not start writing a miss to or reading a hit from disk if it estimates that the swap operation will take more than the specified number of milliseconds. By default and when set to zero, disables the disk I/O time limit enforcement. Ignored when using blocking I/O module because blocking synchronous I/O does not allow Squid to estimate the expected swap wait time. max-swap-rate=swaps/sec: Artificially limits disk access using the specified I/O rate limit. Swap out requests that would cause the average I/O rate to exceed the limit are delayed. Individual swap in requests (i.e., hits or reads) are not delayed, but they do contribute to measured swap rate and since they are placed in the same FIFO queue as swap out requests, they may wait longer if max-swap-rate is smaller. This is necessary on file systems that buffer "too many" writes and then start blocking Squid and other processes while committing those writes to disk. Usually used together with swap-timeout to avoid excessive delays and queue overflows when disk demand exceeds available disk "bandwidth". By default and when set to zero, disables the disk I/O rate limit enforcement. Currently supported by IpcIo module only. slot-size=bytes: The size of a database "record" used for storing cached responses. A cached response occupies at least one slot and all database I/O is done using individual slots so increasing this parameter leads to more disk space waste while decreasing it leads to more disk I/O overheads. Should be a multiple of your operating system I/O page size. Defaults to 16KBytes. A housekeeping header is stored with each slot and smaller slot-sizes will be rejected. The header is smaller than 100 bytes. ==== COMMON OPTIONS ==== no-store no new objects should be stored to this cache_dir. min-size=n the minimum object size in bytes this cache_dir will accept. It's used to restrict a cache_dir to only store large objects (e.g. AUFS) while other stores are optimized for smaller objects (e.g. Rock). Defaults to 0. max-size=n the maximum object size in bytes this cache_dir supports. The value in maximum_object_size directive sets the default unless more specific details are available (ie a small store capacity). Note: To make optimal use of the max-size limits you should order the cache_dir lines with the smallest max-size value first. NOCOMMENT_START # Uncomment and adjust the following to add a disk cache directory. #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256 NOCOMMENT_END DOC_END NAME: store_dir_select_algorithm TYPE: string LOC: Config.store_dir_select_algorithm DEFAULT: least-load DOC_START How Squid selects which cache_dir to use when the response object will fit into more than one. Regardless of which algorithm is used the cache_dir min-size and max-size parameters are obeyed. As such they can affect the selection algorithm by limiting the set of considered cache_dir. Algorithms: least-load This algorithm is suited to caches with similar cache_dir sizes and disk speeds. The disk with the least I/O pending is selected. When there are multiple disks with the same I/O load ranking the cache_dir with most available capacity is selected. When a mix of cache_dir sizes are configured the faster disks have a naturally lower I/O loading and larger disks have more capacity. So space used to store objects and data throughput may be very unbalanced towards larger disks. round-robin This algorithm is suited to caches with unequal cache_dir disk sizes. Each cache_dir is selected in a rotation. The next suitable cache_dir is used. Available cache_dir capacity is only considered in relation to whether the object will fit and meets the min-size and max-size parameters. Disk I/O loading is only considered to prevent overload on slow disks. This algorithm does not spread objects by size, so any I/O loading per-disk may appear very unbalanced and volatile. If several cache_dirs use similar min-size, max-size, or other limits to to reject certain responses, then do not group such cache_dir lines together, to avoid round-robin selection bias towards the first cache_dir after the group. Instead, interleave cache_dir lines from different groups. For example: store_dir_select_algorithm round-robin cache_dir rock /hdd1 ... min-size=100000 cache_dir rock /ssd1 ... max-size=99999 cache_dir rock /hdd2 ... min-size=100000 cache_dir rock /ssd2 ... max-size=99999 cache_dir rock /hdd3 ... min-size=100000 cache_dir rock /ssd3 ... max-size=99999 DOC_END NAME: max_open_disk_fds TYPE: int LOC: Config.max_open_disk_fds DEFAULT: 0 DEFAULT_DOC: no limit DOC_START To avoid having disk as the I/O bottleneck Squid can optionally bypass the on-disk cache if more than this amount of disk file descriptors are open. A value of 0 indicates no limit. DOC_END NAME: cache_swap_low COMMENT: (percent, 0-100) TYPE: int DEFAULT: 90 LOC: Config.Swap.lowWaterMark DOC_START The low-water mark for AUFS/UFS/diskd cache object eviction by the cache_replacement_policy algorithm. Removal begins when the swap (disk) usage of a cache_dir is above this low-water mark and attempts to maintain utilization near the low-water mark. As swap utilization increases towards the high-water mark set by cache_swap_high object eviction becomes more agressive. The value difference in percentages between low- and high-water marks represent an eviction rate of 300 objects per second and the rate continues to scale in agressiveness by multiples of this above the high-water mark. Defaults are 90% and 95%. If you have a large cache, 5% could be hundreds of MB. If this is the case you may wish to set these numbers closer together. See also cache_swap_high and cache_replacement_policy DOC_END NAME: cache_swap_high COMMENT: (percent, 0-100) TYPE: int DEFAULT: 95 LOC: Config.Swap.highWaterMark DOC_START The high-water mark for AUFS/UFS/diskd cache object eviction by the cache_replacement_policy algorithm. Removal begins when the swap (disk) usage of a cache_dir is above the low-water mark set by cache_swap_low and attempts to maintain utilization near the low-water mark. As swap utilization increases towards this high-water mark object eviction becomes more agressive. The value difference in percentages between low- and high-water marks represent an eviction rate of 300 objects per second and the rate continues to scale in agressiveness by multiples of this above the high-water mark. Defaults are 90% and 95%. If you have a large cache, 5% could be hundreds of MB. If this is the case you may wish to set these numbers closer together. See also cache_swap_low and cache_replacement_policy DOC_END COMMENT_START LOGFILE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: logformat TYPE: logformat LOC: Log::TheConfig DEFAULT: none DEFAULT_DOC: The format definitions squid, common, combined, referrer, useragent are built in. DOC_START Usage: logformat Defines an access log format. The is a string with embedded % format codes % format codes all follow the same basic structure where all components but the formatcode are optional and usually unnecessary, especially when dealing with common codes. % [encoding] [-] [[0]width] [{arg}] formatcode [{arg}] encoding escapes or otherwise protects "special" characters: " Quoted string encoding where quote(") and backslash(\) characters are \-escaped while CR, LF, and TAB characters are encoded as \r, \n, and \t two-character sequences. [ Custom Squid encoding where percent(%), square brackets([]), backslash(\) and characters with codes outside of [32,126] range are %-encoded. SP is not encoded. Used by log_mime_hdrs. # URL encoding (a.k.a. percent-encoding) where all URL unsafe and control characters (per RFC 1738) are %-encoded. / Shell-like encoding where quote(") and backslash(\) characters are \-escaped while CR and LF characters are encoded as \r and \n two-character sequences. Values containing SP character(s) are surrounded by quotes("). ' Raw/as-is encoding with no escaping/quoting. Default encoding: When no explicit encoding is specified, each %code determines its own encoding. Most %codes use raw/as-is encoding, but some codes use a so called "pass-through URL encoding" where all URL unsafe and control characters (per RFC 1738) are %-encoded, but the percent character(%) is left as is. - left aligned width minimum and/or maximum field width: [width_min][.width_max] When minimum starts with 0, the field is zero-padded. String values exceeding maximum width are truncated. {arg} argument such as header name etc. This field may be placed before or after the token, but not both at once. Format codes: % a literal % character sn Unique sequence number per log line entry err_code The ID of an error response served by Squid or a similar internal error identifier. err_detail Additional err_code-dependent error information. note The annotation specified by the argument. Also logs the adaptation meta headers set by the adaptation_meta configuration parameter. If no argument given all annotations logged. The argument may include a separator to use with annotation values: name[:separator] By default, multiple note values are separated with "," and multiple notes are separated with "\r\n". When logging named notes with %{name}note, the explicitly configured separator is used between note values. When logging all notes with %note, the explicitly configured separator is used between individual notes. There is currently no way to specify both value and notes separators when logging all notes with %note. master_xaction The master transaction identifier is an unsigned integer. These IDs are guaranteed to monotonically increase within a single worker process lifetime, with higher values corresponding to transactions that were accepted or initiated later. Due to current implementation deficiencies, some IDs are skipped (i.e. never logged). Concurrent workers and restarted workers use similar, overlapping sequences of master transaction IDs. Connection related format codes: >a Client source IP address >A Client FQDN >p Client source port >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier) >la Local IP address the client connected to >lp Local port number the client connected to >qos Client connection TOS/DSCP value set by Squid >nfmark Client connection netfilter packet MARK set by Squid la Local listening IP address the client connection was connected to. lp Local listening port number the client connection was connected to. handshake Raw client handshake Initial client bytes received by Squid on a newly accepted TCP connection or inside a just established CONNECT tunnel. Squid stops accumulating handshake bytes as soon as the handshake parser succeeds or fails (determining whether the client is using the expected protocol). For HTTP clients, the handshake is the request line. For TLS clients, the handshake consists of all TLS records up to and including the TLS record that contains the last byte of the first ClientHello message. For clients using an unsupported protocol, this field contains the bytes received by Squid at the time of the handshake parsing failure. See the on_unsupported_protocol directive for more information on Squid handshake traffic expectations. Current support is limited to these contexts: - http_port connections, but only when the on_unsupported_protocol directive is in use. - https_port connections (and CONNECT tunnels) that are subject to the ssl_bump peek or stare action. To protect binary handshake data, this field is always base64-encoded (RFC 4648 Section 4). If logformat field encoding is configured, that encoding is applied on top of base64. Otherwise, the computed base64 value is recorded as is. Time related format codes: ts Seconds since epoch tu subsecond time (milliseconds) tl Local time. Optional strftime format argument default %d/%b/%Y:%H:%M:%S %z tg GMT time. Optional strftime format argument default %d/%b/%Y:%H:%M:%S %z tr Response time (milliseconds) dt Total time spent making DNS lookups (milliseconds) tS Approximate master transaction start time in . format. Currently, Squid considers the master transaction started when a complete HTTP request header initiating the transaction is received from the client. This is the same value that Squid uses to calculate transaction response time when logging %tr to access.log. Currently, Squid uses millisecond resolution for %tS values, similar to the default access.log "current time" field (%ts.%03tu). Access Control related format codes: et Tag returned by external acl ea Log string returned by external acl un User name (any available) ul User name from authentication ue User name from external acl helper ui User name from ident un A user name. Expands to the first available name from the following list of information sources: - authenticated user name, like %ul - user name supplied by an external ACL, like %ue - SSL client name, like %us - ident user name, like %ui credentials Client credentials. The exact meaning depends on the authentication scheme: For Basic authentication, it is the password; for Digest, the realm sent by the client; for NTLM and Negotiate, the client challenge or client credentials prefixed with "YR " or "KK ". HTTP related format codes: REQUEST [http::]rm Request method (GET/POST etc) [http::]>rm Request method from client [http::]ru Request URL received from the client (or computed) Computed URLs are URIs of internally generated requests and various "error:..." URIs. Unlike %ru, this request URI is not affected by request adaptation, URL rewriting services, and strip_query_terms. Honors uri_whitespace. This field is using pass-through URL encoding by default. Encoding this field using other variants of %-encoding will clash with uri_whitespace modifications that also use %-encoding. [http::]rs Request URL scheme from client [http::]rd Request URL domain from client [http::]rP Request URL port from client [http::]rp Request URL path excluding hostname from client [http::]rv Request protocol version from client [http::]h Original received request header. Usually differs from the request header sent by Squid, although most fields are often preserved. Accepts optional header field name/value filter argument using name[:[separator]element] format. [http::]>ha Received request header after adaptation and redirection (pre-cache REQMOD vectoring point). Usually differs from the request header sent by Squid, although most fields are often preserved. Optional header name argument as for >h RESPONSE [http::]Hs HTTP status code sent to the client [http::]h [http::]mt MIME content type SIZE COUNTERS [http::]st Total size of request + reply traffic with client [http::]>st Total size of request received from client. Excluding chunked encoding bytes. [http::]sh Size of request headers received from client [http::]sni SSL client SNI sent to Squid. ssl::>cert_subject The Subject field of the received client SSL certificate or a dash ('-') if Squid has received an invalid/malformed certificate or no certificate at all. Consider encoding the logged value because Subject often has spaces. ssl::>cert_issuer The Issuer field of the received client SSL certificate or a dash ('-') if Squid has received an invalid/malformed certificate or no certificate at all. Consider encoding the logged value because Issuer often has spaces. ssl::negotiated_version The negotiated TLS version of the client connection. %ssl::received_hello_version The TLS version of the Hello message received from TLS client. %ssl::received_supported_version The maximum TLS version supported by the TLS client. %ssl::negotiated_cipher The negotiated cipher of the client connection. %ssl::h PROXY protocol header, including optional TLVs. Supports the same field and element reporting/extraction logic as %http::>h. For configuration and reporting purposes, Squid maps each PROXY TLV to an HTTP header field: the TLV type (configured as a decimal integer) is the field name, and the TLV value is the field value. All TLVs of "LOCAL" connections (in PROXY protocol terminology) are currently skipped/ignored. Squid also maps the following standard PROXY protocol header blocks to pseudo HTTP headers (their names use PROXY terminology and start with a colon, following HTTP tradition for pseudo headers): :command, :version, :src_addr, :dst_addr, :src_port, and :dst_port. Without optional parameters, this logformat code logs pseudo headers and TLVs. This format code uses pass-through URL encoding by default. Example: # relay custom PROXY TLV #224 to adaptation services adaptation_meta Client-Foo "%proxy_protocol::>h{224}" See also: %http::>h The default formats available (which do not need re-defining) are: logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %h" "%{User-Agent}>h" %Ss:%Sh logformat referrer %ts.%03tu %>a %{Referer}>h %ru logformat useragent %>a [%tl] "%{User-Agent}>h" NOTE: When the log_mime_hdrs directive is set to ON. The squid, common and combined formats have a safely encoded copy of the mime headers appended to each line within a pair of brackets. NOTE: The common and combined formats are not quite true to the Apache definition. The logs from Squid contain an extra status and hierarchy code appended. DOC_END NAME: access_log cache_access_log TYPE: access_log LOC: Config.Log.accesslogs DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid DOC_START Configures whether and how Squid logs HTTP and ICP transactions. If access logging is enabled, a single line is logged for every matching HTTP or ICP request. The recommended directive formats are: access_log : [option ...] [acl acl ...] access_log none [acl acl ...] The following directive format is accepted but may be deprecated: access_log : [ [acl acl ...]] In most cases, the first ACL name must not contain the '=' character and should not be equal to an existing logformat name. You can always start with an 'all' ACL to work around those restrictions. Will log to the specified module:place using the specified format (which must be defined in a logformat directive) those entries which match ALL the acl's specified (which must be defined in acl clauses). If no acl is specified, all requests will be logged to this destination. ===== Available options for the recommended directive format ===== logformat=name Names log line format (either built-in or defined by a logformat directive). Defaults to 'squid'. buffer-size=64KB Defines approximate buffering limit for log records (see buffered_logs). Squid should not keep more than the specified size and, hence, should flush records before the buffer becomes full to avoid overflows under normal conditions (the exact flushing algorithm is module-dependent though). The on-error option controls overflow handling. on-error=die|drop Defines action on unrecoverable errors. The 'drop' action ignores (i.e., does not log) affected log records. The default 'die' action kills the affected worker. The drop action support has not been tested for modules other than tcp. rotate=N Specifies the number of log file rotations to make when you run 'squid -k rotate'. The default is to obey the logfile_rotate directive. Setting rotate=0 will disable the file name rotation, but the log files are still closed and re-opened. This will enable you to rename the logfiles yourself just before sending the rotate signal. Only supported by the stdio module. ===== Modules Currently available ===== none Do not log any requests matching these ACL. Do not specify Place or logformat name. stdio Write each log line to disk immediately at the completion of each request. Place: the filename and path to be written. daemon Very similar to stdio. But instead of writing to disk the log line is passed to a daemon helper for asychronous handling instead. Place: varies depending on the daemon. log_file_daemon Place: the file name and path to be written. syslog To log each request via syslog facility. Place: The syslog facility and priority level for these entries. Place Format: facility.priority where facility could be any of: authpriv, daemon, local0 ... local7 or user. And priority could be any of: err, warning, notice, info, debug. udp To send each log line as text data to a UDP receiver. Place: The destination host name or IP and port. Place Format: //host:port tcp To send each log line as text data to a TCP receiver. Lines may be accumulated before sending (see buffered_logs). Place: The destination host name or IP and port. Place Format: //host:port Default: access_log daemon:@DEFAULT_ACCESS_LOG@ squid DOC_END NAME: icap_log TYPE: access_log IFDEF: ICAP_CLIENT LOC: Config.Log.icaplogs DEFAULT: none DOC_START ICAP log files record ICAP transaction summaries, one line per transaction. The icap_log option format is: icap_log [ [acl acl ...]] icap_log none [acl acl ...]] Please see access_log option documentation for details. The two kinds of logs share the overall configuration approach and many features. ICAP processing of a single HTTP message or transaction may require multiple ICAP transactions. In such cases, multiple ICAP transaction log lines will correspond to a single access log line. ICAP log supports many access.log logformat %codes. In ICAP context, HTTP message-related %codes are applied to the HTTP message embedded in an ICAP message. Logformat "%http::>..." codes are used for HTTP messages embedded in ICAP requests while "%http::<..." codes are used for HTTP messages embedded in ICAP responses. For example: http::>h To-be-adapted HTTP message headers sent by Squid to the ICAP service. For REQMOD transactions, these are HTTP request headers. For RESPMOD, these are HTTP response headers, but Squid currently cannot log them (i.e., %http::>h will expand to "-" for RESPMOD). http::st The total size of the ICAP request sent to the ICAP server (ICAP headers + ICAP body), including chunking metadata (if any). icap::h ICAP request header(s). Similar to >h. icap::A %icap::to/%03icap::Hs %icap::\n - logfile data R\n - rotate file T\n - truncate file O\n - reopen file F\n - flush file r\n - set rotate count to b\n - 1 = buffer output, 0 = don't buffer output No responses is expected. DOC_END NAME: stats_collection TYPE: acl_access LOC: Config.accessList.stats_collection DEFAULT: none DEFAULT_DOC: Allow logging for all transactions. COMMENT: allow|deny acl acl... DOC_START This options allows you to control which requests gets accounted in performance counters. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: cache_store_log TYPE: string DEFAULT: none LOC: Config.Log.store DOC_START Logs the activities of the storage manager. Shows which objects are ejected from the cache, and which objects are saved and for how long. There are not really utilities to analyze this data, so you can safely disable it (the default). Store log uses modular logging outputs. See access_log for the list of modules supported. Example: cache_store_log stdio:@DEFAULT_STORE_LOG@ cache_store_log daemon:@DEFAULT_STORE_LOG@ DOC_END NAME: cache_swap_state cache_swap_log TYPE: string LOC: Config.Log.swap DEFAULT: none DEFAULT_DOC: Store the journal inside its cache_dir DOC_START Location for the cache "swap.state" file. This index file holds the metadata of objects saved on disk. It is used to rebuild the cache during startup. Normally this file resides in each 'cache_dir' directory, but you may specify an alternate pathname here. Note you must give a full filename, not just a directory. Since this is the index for the whole object list you CANNOT periodically rotate it! If %s can be used in the file name it will be replaced with a a representation of the cache_dir name where each / is replaced with '.'. This is needed to allow adding/removing cache_dir lines when cache_swap_log is being used. If have more than one 'cache_dir', and %s is not used in the name these swap logs will have names such as: cache_swap_log.00 cache_swap_log.01 cache_swap_log.02 The numbered extension (which is added automatically) corresponds to the order of the 'cache_dir' lines in this configuration file. If you change the order of the 'cache_dir' lines in this file, these index files will NOT correspond to the correct 'cache_dir' entry (unless you manually rename them). We recommend you do NOT use this option. It is better to keep these index files in each 'cache_dir' directory. DOC_END NAME: logfile_rotate TYPE: int DEFAULT: 10 LOC: Config.Log.rotateNumber DOC_START Specifies the default number of logfile rotations to make when you type 'squid -k rotate'. The default is 10, which will rotate with extensions 0 through 9. Setting logfile_rotate to 0 will disable the file name rotation, but the logfiles are still closed and re-opened. This will enable you to rename the logfiles yourself just before sending the rotate signal. Note, from Squid-3.1 this option is only a default for cache.log, that log can be rotated separately by using debug_options. Note, from Squid-4 this option is only a default for access.log recorded by stdio: module. Those logs can be rotated separately by using the rotate=N option on their access_log directive. Note, the 'squid -k rotate' command normally sends a USR1 signal to the running squid process. In certain situations (e.g. on Linux with Async I/O), USR1 is used for other purposes, so -k rotate uses another signal. It is best to get in the habit of using 'squid -k rotate' instead of 'kill -USR1 '. DOC_END NAME: mime_table TYPE: string DEFAULT: @DEFAULT_MIME_TABLE@ LOC: Config.mimeTablePathname DOC_START Path to Squid's icon configuration file. You shouldn't need to change this, but the default file contains examples and formatting information if you do. DOC_END NAME: log_mime_hdrs COMMENT: on|off TYPE: onoff LOC: Config.onoff.log_mime_hdrs DEFAULT: off DOC_START The Cache can record both the request and the response MIME headers for each HTTP transaction. The headers are encoded safely and will appear as two bracketed fields at the end of the access log (for either the native or httpd-emulated log formats). To enable this logging set log_mime_hdrs to 'on'. DOC_END NAME: pid_filename TYPE: string DEFAULT: @DEFAULT_PID_FILE@ LOC: Config.pidFilename DOC_START A filename to write the process-id to. To disable, enter "none". DOC_END NAME: client_netmask TYPE: address LOC: Config.Addrs.client_netmask DEFAULT: no_addr DEFAULT_DOC: Log full client IP address DOC_START A netmask for client addresses in logfiles and cachemgr output. Change this to protect the privacy of your cache clients. A netmask of 255.255.255.0 will log all IP's in that range with the last digit set to '0'. DOC_END NAME: strip_query_terms TYPE: onoff LOC: Config.onoff.strip_query_terms DEFAULT: on DOC_START By default, Squid strips query terms from requested URLs before logging. This protects your user's privacy and reduces log size. When investigating HIT/MISS or other caching behaviour you will need to disable this to see the full URL used by Squid. DOC_END NAME: buffered_logs COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.buffered_logs DOC_START Whether to write/send access_log records ASAP or accumulate them and then write/send them in larger chunks. Buffering may improve performance because it decreases the number of I/Os. However, buffering increases the delay before log records become available to the final recipient (e.g., a disk file or logging daemon) and, hence, increases the risk of log records loss. Note that even when buffered_logs are off, Squid may have to buffer records if it cannot write/send them immediately due to pending I/Os (e.g., the I/O writing the previous log record) or connectivity loss. Currently honored by 'daemon' and 'tcp' access_log modules only. DOC_END NAME: netdb_filename TYPE: string DEFAULT: stdio:@DEFAULT_NETDB_FILE@ LOC: Config.netdbFilename IFDEF: USE_ICMP DOC_START Where Squid stores it's netdb journal. When enabled this journal preserves netdb state between restarts. To disable, enter "none". DOC_END COMMENT_START OPTIONS FOR TROUBLESHOOTING ----------------------------------------------------------------------------- COMMENT_END NAME: cache_log TYPE: string DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@ LOC: Debug::cache_log DOC_START Squid administrative logging file. This is where general information about Squid behavior goes. You can increase the amount of data logged to this file and how often it is rotated with "debug_options" DOC_END NAME: debug_options TYPE: eol DEFAULT: ALL,1 DEFAULT_DOC: Log all critical and important messages. LOC: Debug::debugOptions DOC_START Logging options are set as section,level where each source file is assigned a unique section. Lower levels result in less output, Full debugging (level 9) can result in a very large log file, so be careful. The magic word "ALL" sets debugging levels for all sections. The default is to run with "ALL,1" to record important warnings. The rotate=N option can be used to keep more or less of these logs than would otherwise be kept by logfile_rotate. For most uses a single log should be enough to monitor current events affecting Squid. DOC_END NAME: coredump_dir TYPE: string LOC: Config.coredump_dir DEFAULT_IF_NONE: none DEFAULT_DOC: Use the directory from where Squid was started. DOC_START By default Squid leaves core files in the directory from where it was started. If you set 'coredump_dir' to a directory that exists, Squid will chdir() to that directory at startup and coredump files will be left there. NOCOMMENT_START # Leave coredumps in the first cache dir coredump_dir @DEFAULT_SWAP_DIR@ NOCOMMENT_END DOC_END COMMENT_START OPTIONS FOR FTP GATEWAYING ----------------------------------------------------------------------------- COMMENT_END NAME: ftp_user TYPE: string DEFAULT: Squid@ LOC: Config.Ftp.anon_user DOC_START If you want the anonymous login password to be more informative (and enable the use of picky FTP servers), set this to something reasonable for your domain, like wwwuser@somewhere.net The reason why this is domainless by default is the request can be made on the behalf of a user in any domain, depending on how the cache is used. Some FTP server also validate the email address is valid (for example perl.com). DOC_END NAME: ftp_passive TYPE: onoff DEFAULT: on LOC: Config.Ftp.passive DOC_START If your firewall does not allow Squid to use passive connections, turn off this option. Use of ftp_epsv_all option requires this to be ON. DOC_END NAME: ftp_epsv_all TYPE: onoff DEFAULT: off LOC: Config.Ftp.epsv_all DOC_START FTP Protocol extensions permit the use of a special "EPSV ALL" command. NATs may be able to put the connection on a "fast path" through the translator, as the EPRT command will never be used and therefore, translation of the data portion of the segments will never be needed. When a client only expects to do two-way FTP transfers this may be useful. If squid finds that it must do a three-way FTP transfer after issuing an EPSV ALL command, the FTP session will fail. If you have any doubts about this option do not use it. Squid will nicely attempt all other connection methods. Requires ftp_passive to be ON (default) for any effect. DOC_END NAME: ftp_epsv TYPE: ftp_epsv DEFAULT: none LOC: Config.accessList.ftp_epsv DOC_START FTP Protocol extensions permit the use of a special "EPSV" command. NATs may be able to put the connection on a "fast path" through the translator using EPSV, as the EPRT command will never be used and therefore, translation of the data portion of the segments will never be needed. EPSV is often required to interoperate with FTP servers on IPv6 networks. On the other hand, it may break some IPv4 servers. By default, EPSV may try EPSV with any FTP server. To fine tune that decision, you may restrict EPSV to certain clients or servers using ACLs: ftp_epsv allow|deny al1 acl2 ... WARNING: Disabling EPSV may cause problems with external NAT and IPv6. Only fast ACLs are supported. Requires ftp_passive to be ON (default) for any effect. DOC_END NAME: ftp_eprt TYPE: onoff DEFAULT: on LOC: Config.Ftp.eprt DOC_START FTP Protocol extensions permit the use of a special "EPRT" command. This extension provides a protocol neutral alternative to the IPv4-only PORT command. When supported it enables active FTP data channels over IPv6 and efficient NAT handling. Turning this OFF will prevent EPRT being attempted and will skip straight to using PORT for IPv4 servers. Some devices are known to not handle this extension correctly and may result in crashes. Devices which suport EPRT enough to fail cleanly will result in Squid attempting PORT anyway. This directive should only be disabled when EPRT results in device failures. WARNING: Doing so will convert Squid back to the old behavior with all the related problems with external NAT devices/layers and IPv4-only FTP. DOC_END NAME: ftp_sanitycheck TYPE: onoff DEFAULT: on LOC: Config.Ftp.sanitycheck DOC_START For security and data integrity reasons Squid by default performs sanity checks of the addresses of FTP data connections ensure the data connection is to the requested server. If you need to allow FTP connections to servers using another IP address for the data connection turn this off. DOC_END NAME: ftp_telnet_protocol TYPE: onoff DEFAULT: on LOC: Config.Ftp.telnet DOC_START The FTP protocol is officially defined to use the telnet protocol as transport channel for the control connection. However, many implementations are broken and does not respect this aspect of the FTP protocol. If you have trouble accessing files with ASCII code 255 in the path or similar problems involving this ASCII code you can try setting this directive to off. If that helps, report to the operator of the FTP server in question that their FTP server is broken and does not follow the FTP standard. DOC_END COMMENT_START OPTIONS FOR EXTERNAL SUPPORT PROGRAMS ----------------------------------------------------------------------------- COMMENT_END NAME: diskd_program TYPE: string DEFAULT: @DEFAULT_DISKD@ LOC: Config.Program.diskd DOC_START Specify the location of the diskd executable. Note this is only useful if you have compiled in diskd as one of the store io modules. DOC_END NAME: unlinkd_program IFDEF: USE_UNLINKD TYPE: string DEFAULT: @DEFAULT_UNLINKD@ LOC: Config.Program.unlinkd DOC_START Specify the location of the executable for file deletion process. DOC_END NAME: pinger_program IFDEF: USE_ICMP TYPE: icmp DEFAULT: @DEFAULT_PINGER@ LOC: IcmpCfg DOC_START Specify the location of the executable for the pinger process. DOC_END NAME: pinger_enable TYPE: onoff DEFAULT: on LOC: IcmpCfg.enable IFDEF: USE_ICMP DOC_START Control whether the pinger is active at run-time. Enables turning ICMP pinger on and off with a simple squid -k reconfigure. DOC_END COMMENT_START OPTIONS FOR URL REWRITING ----------------------------------------------------------------------------- COMMENT_END NAME: url_rewrite_program redirect_program TYPE: wordlist LOC: Config.Program.redirect DEFAULT: none DOC_START The name and command line parameters of an admin-provided executable for redirecting clients or adjusting/replacing client request URLs. This helper is consulted after the received request is cleared by http_access and adapted using eICAP/ICAP services (if any). If the helper does not redirect the client, Squid checks adapted_http_access and may consult the cache or forward the request to the next hop. For each request, the helper gets one line in the following format: [channel-ID ] request-URL [ extras] Use url_rewrite_extras to configure what Squid sends as 'extras'. The helper must reply to each query using a single line: [channel-ID ] result [ kv-pairs] The result section must match exactly one of the following outcomes: OK [status=30N] url="..." Redirect the client to a URL supplied in the 'url' parameter. Optional 'status' specifies the status code to send to the client in Squid's HTTP redirect response. It must be one of the standard HTTP redirect status codes: 301, 302, 303, 307, or 308. When no specific status is requested, Squid uses 302. OK rewrite-url="..." Replace the current request URL with the one supplied in the 'rewrite-url' parameter. Squid fetches the resource specified by the new URL and forwards the received response (or its cached copy) to the client. WARNING: Avoid rewriting URLs! When possible, redirect the client using an "OK url=..." helper response instead. Rewriting URLs may create inconsistent requests and/or break synchronization between internal client and origin server states, especially when URLs or other message parts contain snippets of that state. For example, Squid does not adjust Location headers and embedded URLs after the helper rewrites the request URL. OK Keep the client request intact. ERR Keep the client request intact. BH [message="..."] A helper problem that should be reported to the Squid admin via a level-1 cache.log message. The 'message' parameter is reserved for specifying the log message. In addition to the kv-pairs mentioned above, Squid also understands the following optional kv-pairs in URL rewriter responses: clt_conn_tag=TAG Associates a TAG with the client TCP connection. The clt_conn_tag=TAG pair is treated as a regular transaction annotation for the current request and also annotates future requests on the same client connection. A helper may update the TAG during subsequent requests by returning a new kv-pair. Helper messages contain the channel-ID part if and only if the url_rewrite_children directive specifies positive concurrency. As a channel-ID value, Squid sends a number between 0 and concurrency-1. The helper must echo back the received channel-ID in its response. By default, Squid does not use a URL rewriter. DOC_END NAME: url_rewrite_children redirect_children TYPE: HelperChildConfig DEFAULT: 20 startup=0 idle=1 concurrency=0 LOC: Config.redirectChildren DOC_START Specifies the maximum number of redirector processes that Squid may spawn (numberofchildren) and several related options. Using too few of these helper processes (a.k.a. "helpers") creates request queues. Using too many helpers wastes your system resources. Usage: numberofchildren [option]... The startup= and idle= options allow some measure of skew in your tuning. startup= Sets a minimum of how many processes are to be spawned when Squid starts or reconfigures. When set to zero the first request will cause spawning of the first child process to handle it. Starting too few will cause an initial slowdown in traffic as Squid attempts to simultaneously spawn enough processes to cope. idle= Sets a minimum of how many processes Squid is to try and keep available at all times. When traffic begins to rise above what the existing processes can handle this many more will be spawned up to the maximum configured. A minimum setting of 1 is required. concurrency= The number of requests each redirector helper can handle in parallel. Defaults to 0 which indicates the redirector is a old-style single threaded redirector. When this directive is set to a value >= 1 then the protocol used to communicate with the helper is modified to include an ID in front of the request/response. The ID from the request must be echoed back with the response to that request. queue-size=N Sets the maximum number of queued requests. A request is queued when no existing child can accept it due to concurrency limit and no new child can be started due to numberofchildren limit. The default maximum is zero if url_rewrite_bypass is enabled and 2*numberofchildren otherwise. If the queued requests exceed queue size and redirector_bypass configuration option is set, then redirector is bypassed. Otherwise, Squid is allowed to temporarily exceed the configured maximum, marking the affected helper as "overloaded". If the helper overload lasts more than 3 minutes, the action prescribed by the on-persistent-overload option applies. on-persistent-overload=action Specifies Squid reaction to a new helper request arriving when the helper has been overloaded for more that 3 minutes already. The number of queued requests determines whether the helper is overloaded (see the queue-size option). Two actions are supported: die Squid worker quits. This is the default behavior. ERR Squid treats the helper request as if it was immediately submitted, and the helper immediately replied with an ERR response. This action has no effect on the already queued and in-progress helper requests. DOC_END NAME: url_rewrite_host_header redirect_rewrites_host_header TYPE: onoff DEFAULT: on LOC: Config.onoff.redir_rewrites_host DOC_START To preserve same-origin security policies in browsers and prevent Host: header forgery by redirectors Squid rewrites any Host: header in redirected requests. If you are running an accelerator this may not be a wanted effect of a redirector. This directive enables you disable Host: alteration in reverse-proxy traffic. WARNING: Entries are cached on the result of the URL rewriting process, so be careful if you have domain-virtual hosts. WARNING: Squid and other software verifies the URL and Host are matching, so be careful not to relay through other proxies or inspecting firewalls with this disabled. DOC_END NAME: url_rewrite_access redirector_access TYPE: acl_access DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. LOC: Config.accessList.redirector DOC_START If defined, this access list specifies which requests are sent to the redirector processes. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: url_rewrite_bypass redirector_bypass TYPE: onoff LOC: Config.onoff.redirector_bypass DEFAULT: off DOC_START When this is 'on', a request will not go through the redirector if all the helpers are busy. If this is 'off' and the redirector queue grows too large, the action is prescribed by the on-persistent-overload option. You should only enable this if the redirectors are not critical to your caching system. If you use redirectors for access control, and you enable this option, users may have access to pages they should not be allowed to request. Enabling this option sets the default url_rewrite_children queue-size option value to 0. DOC_END NAME: url_rewrite_extras TYPE: TokenOrQuotedString LOC: Config.redirector_extras DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp" DOC_START Specifies a string to be append to request line format for the rewriter helper. "Quoted" format values may contain spaces and logformat %macros. In theory, any logformat %macro can be used. In practice, a %macro expands as a dash (-) if the helper request is sent before the required macro information is available to Squid. DOC_END NAME: url_rewrite_timeout TYPE: UrlHelperTimeout LOC: Config.onUrlRewriteTimeout DEFAULT: none DEFAULT_DOC: Squid waits for the helper response forever DOC_START Squid times active requests to redirector. The timeout value and Squid reaction to a timed out request are configurable using the following format: url_rewrite_timeout timeout time-units on_timeout= [response=] supported timeout actions: fail Squid return a ERR_GATEWAY_FAILURE error page bypass Do not re-write the URL retry Send the lookup to the helper again use_configured_response Use the as helper response DOC_END COMMENT_START OPTIONS FOR STORE ID ----------------------------------------------------------------------------- COMMENT_END NAME: store_id_program storeurl_rewrite_program TYPE: wordlist LOC: Config.Program.store_id DEFAULT: none DOC_START Specify the location of the executable StoreID helper to use. Since they can perform almost any function there isn't one included. For each requested URL, the helper will receive one line with the format [channel-ID ] URL [ extras] After processing the request the helper must reply using the following format: [channel-ID ] result [ kv-pairs] The result code can be: OK store-id="..." Use the StoreID supplied in 'store-id='. ERR The default is to use HTTP request URL as the store ID. BH An internal error occurred in the helper, preventing a result being identified. In addition to the above kv-pairs Squid also understands the following optional kv-pairs received from URL rewriters: clt_conn_tag=TAG Associates a TAG with the client TCP connection. Please see url_rewrite_program related documentation for this kv-pair Helper programs should be prepared to receive and possibly ignore additional whitespace-separated tokens on each input line. When using the concurrency= option the protocol is changed by introducing a query channel tag in front of the request/response. The query channel tag is a number between 0 and concurrency-1. This value must be echoed back unchanged to Squid as the first part of the response relating to its request. NOTE: when using StoreID refresh_pattern will apply to the StoreID returned from the helper and not the URL. WARNING: Wrong StoreID value returned by a careless helper may result in the wrong cached response returned to the user. By default, a StoreID helper is not used. DOC_END NAME: store_id_extras TYPE: TokenOrQuotedString LOC: Config.storeId_extras DEFAULT: "%>a/%>A %un %>rm myip=%la myport=%lp" DOC_START Specifies a string to be append to request line format for the StoreId helper. "Quoted" format values may contain spaces and logformat %macros. In theory, any logformat %macro can be used. In practice, a %macro expands as a dash (-) if the helper request is sent before the required macro information is available to Squid. DOC_END NAME: store_id_children storeurl_rewrite_children TYPE: HelperChildConfig DEFAULT: 20 startup=0 idle=1 concurrency=0 LOC: Config.storeIdChildren DOC_START Specifies the maximum number of StoreID helper processes that Squid may spawn (numberofchildren) and several related options. Using too few of these helper processes (a.k.a. "helpers") creates request queues. Using too many helpers wastes your system resources. Usage: numberofchildren [option]... The startup= and idle= options allow some measure of skew in your tuning. startup= Sets a minimum of how many processes are to be spawned when Squid starts or reconfigures. When set to zero the first request will cause spawning of the first child process to handle it. Starting too few will cause an initial slowdown in traffic as Squid attempts to simultaneously spawn enough processes to cope. idle= Sets a minimum of how many processes Squid is to try and keep available at all times. When traffic begins to rise above what the existing processes can handle this many more will be spawned up to the maximum configured. A minimum setting of 1 is required. concurrency= The number of requests each storeID helper can handle in parallel. Defaults to 0 which indicates the helper is a old-style single threaded program. When this directive is set to a value >= 1 then the protocol used to communicate with the helper is modified to include an ID in front of the request/response. The ID from the request must be echoed back with the response to that request. queue-size=N Sets the maximum number of queued requests to N. A request is queued when no existing child can accept it due to concurrency limit and no new child can be started due to numberofchildren limit. The default maximum is 2*numberofchildren. If the queued requests exceed queue size and redirector_bypass configuration option is set, then redirector is bypassed. Otherwise, Squid is allowed to temporarily exceed the configured maximum, marking the affected helper as "overloaded". If the helper overload lasts more than 3 minutes, the action prescribed by the on-persistent-overload option applies. on-persistent-overload=action Specifies Squid reaction to a new helper request arriving when the helper has been overloaded for more that 3 minutes already. The number of queued requests determines whether the helper is overloaded (see the queue-size option). Two actions are supported: die Squid worker quits. This is the default behavior. ERR Squid treats the helper request as if it was immediately submitted, and the helper immediately replied with an ERR response. This action has no effect on the already queued and in-progress helper requests. DOC_END NAME: store_id_access storeurl_rewrite_access TYPE: acl_access DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. LOC: Config.accessList.store_id DOC_START If defined, this access list specifies which requests are sent to the StoreID processes. By default all requests are sent. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: store_id_bypass storeurl_rewrite_bypass TYPE: onoff LOC: Config.onoff.store_id_bypass DEFAULT: on DOC_START When this is 'on', a request will not go through the helper if all helpers are busy. If this is 'off' and the helper queue grows too large, the action is prescribed by the on-persistent-overload option. You should only enable this if the helpers are not critical to your caching system. If you use helpers for critical caching components, and you enable this option, users may not get objects from cache. This options sets default queue-size option of the store_id_children to 0. DOC_END COMMENT_START OPTIONS FOR TUNING THE CACHE ----------------------------------------------------------------------------- COMMENT_END NAME: cache no_cache TYPE: acl_access DEFAULT: none DEFAULT_DOC: By default, this directive is unused and has no effect. LOC: Config.accessList.noCache DOC_START Requests denied by this directive will not be served from the cache and their responses will not be stored in the cache. This directive has no effect on other transactions and on already cached responses. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. This and the two other similar caching directives listed below are checked at different transaction processing stages, have different access to response information, affect different cache operations, and differ in slow ACLs support: * cache: Checked before Squid makes a hit/miss determination. No access to reply information! Denies both serving a hit and storing a miss. Supports both fast and slow ACLs. * send_hit: Checked after a hit was detected. Has access to reply (hit) information. Denies serving a hit only. Supports fast ACLs only. * store_miss: Checked before storing a cachable miss. Has access to reply (miss) information. Denies storing a miss only. Supports fast ACLs only. If you are not sure which of the three directives to use, apply the following decision logic: * If your ACL(s) are of slow type _and_ need response info, redesign. Squid does not support that particular combination at this time. Otherwise: * If your directive ACL(s) are of slow type, use "cache"; and/or * if your directive ACL(s) need no response info, use "cache". Otherwise: * If you do not want the response cached, use store_miss; and/or * if you do not want a hit on a cached response, use send_hit. DOC_END NAME: send_hit TYPE: acl_access DEFAULT: none DEFAULT_DOC: By default, this directive is unused and has no effect. LOC: Config.accessList.sendHit DOC_START Responses denied by this directive will not be served from the cache (but may still be cached, see store_miss). This directive has no effect on the responses it allows and on the cached objects. Please see the "cache" directive for a summary of differences among store_miss, send_hit, and cache directives. Unlike the "cache" directive, send_hit only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. For example: # apply custom Store ID mapping to some URLs acl MapMe dstdomain .c.example.com store_id_program ... store_id_access allow MapMe # but prevent caching of special responses # such as 302 redirects that cause StoreID loops acl Ordinary http_status 200-299 store_miss deny MapMe !Ordinary # and do not serve any previously stored special responses # from the cache (in case they were already cached before # the above store_miss rule was in effect). send_hit deny MapMe !Ordinary DOC_END NAME: store_miss TYPE: acl_access DEFAULT: none DEFAULT_DOC: By default, this directive is unused and has no effect. LOC: Config.accessList.storeMiss DOC_START Responses denied by this directive will not be cached (but may still be served from the cache, see send_hit). This directive has no effect on the responses it allows and on the already cached responses. Please see the "cache" directive for a summary of differences among store_miss, send_hit, and cache directives. See the send_hit directive for a usage example. Unlike the "cache" directive, store_miss only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: max_stale COMMENT: time-units TYPE: time_t LOC: Config.maxStale DEFAULT: 1 week DOC_START This option puts an upper limit on how stale content Squid will serve from the cache if cache validation fails. Can be overriden by the refresh_pattern max-stale option. DOC_END NAME: refresh_pattern TYPE: refreshpattern LOC: Config.Refresh DEFAULT: none DOC_START usage: refresh_pattern [-i] regex min percent max [options] By default, regular expressions are CASE-SENSITIVE. To make them case-insensitive, use the -i option. 'Min' is the time (in minutes) an object without an explicit expiry time should be considered fresh. The recommended value is 0, any higher values may cause dynamic applications to be erroneously cached unless the application designer has taken the appropriate actions. 'Percent' is used to compute the max-age value for responses with a Last-Modified header and no Cache-Control:max-age nor Expires. Cache-Control:max-age = ( Date - Last-Modified ) * percent 'Max' is an upper limit on how long objects without an explicit expiry time will be considered fresh. The value is also used to form Cache-Control: max-age header for a request sent from Squid to origin/parent. options: override-expire override-lastmod reload-into-ims ignore-reload ignore-no-store ignore-private max-stale=NN refresh-ims store-stale override-expire enforces min age even if the server sent an explicit expiry time (e.g., with the Expires: header or Cache-Control: max-age). Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. Note: override-expire does not enforce staleness - it only extends freshness / min. If the server returns a Expires time which is longer than your max time, Squid will still consider the object fresh for that period of time. override-lastmod enforces min age even on objects that were modified recently. reload-into-ims changes a client no-cache or ``reload'' request for a cached entry into a conditional request using If-Modified-Since and/or If-None-Match headers, provided the cached entry has a Last-Modified and/or a strong ETag header. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. ignore-reload ignores a client no-cache or ``reload'' header. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. ignore-no-store ignores any ``Cache-control: no-store'' headers received from a server. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. ignore-private ignores any ``Cache-control: private'' headers received from a server. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. refresh-ims causes squid to contact the origin server when a client issues an If-Modified-Since request. This ensures that the client will receive an updated version if one is available. store-stale stores responses even if they don't have explicit freshness or a validator (i.e., Last-Modified or an ETag) present, or if they're already stale. By default, Squid will not cache such responses because they usually can't be reused. Note that such responses will be stale by default. max-stale=NN provide a maximum staleness factor. Squid won't serve objects more stale than this even if it failed to validate the object. Default: use the max_stale global limit. Basically a cached object is: FRESH if expire > now, else STALE STALE if age > max FRESH if lm-factor < percent, else STALE FRESH if age < min else STALE The refresh_pattern lines are checked in the order listed here. The first entry which matches is used. If none of the entries match the default will be used. Note, you must uncomment all the default lines if you want to change one. The default setting is only active if none is used. NOCOMMENT_START # # Add any of your own refresh_pattern entries above these. # refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern . 0 20% 4320 NOCOMMENT_END DOC_END NAME: quick_abort_min COMMENT: (KB) TYPE: kb_int64_t DEFAULT: 16 KB LOC: Config.quickAbort.min DOC_NONE NAME: quick_abort_max COMMENT: (KB) TYPE: kb_int64_t DEFAULT: 16 KB LOC: Config.quickAbort.max DOC_NONE NAME: quick_abort_pct COMMENT: (percent) TYPE: int DEFAULT: 95 LOC: Config.quickAbort.pct DOC_START The cache by default continues downloading aborted requests which are almost completed (less than 16 KB remaining). This may be undesirable on slow (e.g. SLIP) links and/or very busy caches. Impatient users may tie up file descriptors and bandwidth by repeatedly requesting and immediately aborting downloads. When the user aborts a request, Squid will check the quick_abort values to the amount of data transferred until then. If the transfer has less than 'quick_abort_min' KB remaining, it will finish the retrieval. If the transfer has more than 'quick_abort_max' KB remaining, it will abort the retrieval. If more than 'quick_abort_pct' of the transfer has completed, it will finish the retrieval. If you do not want any retrieval to continue after the client has aborted, set both 'quick_abort_min' and 'quick_abort_max' to '0 KB'. If you want retrievals to always continue if they are being cached set 'quick_abort_min' to '-1 KB'. DOC_END NAME: read_ahead_gap COMMENT: buffer-size TYPE: b_int64_t LOC: Config.readAheadGap DEFAULT: 16 KB DOC_START The amount of data the cache will buffer ahead of what has been sent to the client when retrieving an object from another server. DOC_END NAME: negative_ttl IFDEF: USE_HTTP_VIOLATIONS COMMENT: time-units TYPE: time_t LOC: Config.negativeTtl DEFAULT: 0 seconds DOC_START Set the Default Time-to-Live (TTL) for failed requests. Certain types of failures (such as "connection refused" and "404 Not Found") are able to be negatively-cached for a short time. Modern web servers should provide Expires: header, however if they do not this can provide a minimum TTL. The default is not to cache errors with unknown expiry details. Note that this is different from negative caching of DNS lookups. WARNING: Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. DOC_END NAME: positive_dns_ttl COMMENT: time-units TYPE: time_t LOC: Config.positiveDnsTtl DEFAULT: 6 hours DOC_START Upper limit on how long Squid will cache positive DNS responses. Default is 6 hours (360 minutes). This directive must be set larger than negative_dns_ttl. DOC_END NAME: negative_dns_ttl COMMENT: time-units TYPE: time_t LOC: Config.negativeDnsTtl DEFAULT: 1 minutes DOC_START Time-to-Live (TTL) for negative caching of failed DNS lookups. This also sets the lower cache limit on positive lookups. Minimum value is 1 second, and it is not recommendable to go much below 10 seconds. DOC_END NAME: range_offset_limit COMMENT: size [acl acl...] TYPE: acl_b_size_t LOC: Config.rangeOffsetLimit DEFAULT: none DOC_START usage: (size) [units] [[!]aclname] Sets an upper limit on how far (number of bytes) into the file a Range request may be to cause Squid to prefetch the whole file. If beyond this limit, Squid forwards the Range request as it is and the result is NOT cached. This is to stop a far ahead range request (lets say start at 17MB) from making Squid fetch the whole object up to that point before sending anything to the client. Multiple range_offset_limit lines may be specified, and they will be searched from top to bottom on each request until a match is found. The first match found will be used. If no line matches a request, the default limit of 0 bytes will be used. 'size' is the limit specified as a number of units. 'units' specifies whether to use bytes, KB, MB, etc. If no units are specified bytes are assumed. A size of 0 causes Squid to never fetch more than the client requested. (default) A size of 'none' causes Squid to always fetch the object from the beginning so it may cache the result. (2.0 style) 'aclname' is the name of a defined ACL. NP: Using 'none' as the byte value here will override any quick_abort settings that may otherwise apply to the range request. The range request will be fully fetched from start to finish regardless of the client actions. This affects bandwidth usage. DOC_END NAME: minimum_expiry_time COMMENT: (seconds) TYPE: time_t LOC: Config.minimum_expiry_time DEFAULT: 60 seconds DOC_START The minimum caching time according to (Expires - Date) headers Squid honors if the object can't be revalidated. The default is 60 seconds. In reverse proxy environments it might be desirable to honor shorter object lifetimes. It is most likely better to make your server return a meaningful Last-Modified header however. In ESI environments where page fragments often have short lifetimes, this will often be best set to 0. DOC_END NAME: store_avg_object_size COMMENT: (bytes) TYPE: b_int64_t DEFAULT: 13 KB LOC: Config.Store.avgObjectSize DOC_START Average object size, used to estimate number of objects your cache can hold. The default is 13 KB. This is used to pre-seed the cache index memory allocation to reduce expensive reallocate operations while handling clients traffic. Too-large values may result in memory allocation during peak traffic, too-small values will result in wasted memory. Check the cache manager 'info' report metrics for the real object sizes seen by your Squid before tuning this. DOC_END NAME: store_objects_per_bucket TYPE: int DEFAULT: 20 LOC: Config.Store.objectsPerBucket DOC_START Target number of objects per bucket in the store hash table. Lowering this value increases the total number of buckets and also the storage maintenance rate. The default is 20. DOC_END COMMENT_START HTTP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: request_header_max_size COMMENT: (KB) TYPE: b_size_t DEFAULT: 64 KB LOC: Config.maxRequestHeaderSize DOC_START This directives limits the header size of a received HTTP request (including request-line). Increasing this limit beyond its 64 KB default exposes certain old Squid code to various denial-of-service attacks. This limit also applies to received FTP commands. This limit has no direct affect on Squid memory consumption. Squid does not check this limit when sending requests. DOC_END NAME: reply_header_max_size COMMENT: (KB) TYPE: b_size_t DEFAULT: 64 KB LOC: Config.maxReplyHeaderSize DOC_START This directives limits the header size of a received HTTP response (including status-line). Increasing this limit beyond its 64 KB default exposes certain old Squid code to various denial-of-service attacks. This limit also applies to FTP command responses. Squid also checks this limit when loading hit responses from disk cache. Squid does not check this limit when sending responses. DOC_END NAME: request_body_max_size COMMENT: (bytes) TYPE: b_int64_t DEFAULT: 0 KB DEFAULT_DOC: No limit. LOC: Config.maxRequestBodySize DOC_START This specifies the maximum size for an HTTP request body. In other words, the maximum size of a PUT/POST request. A user who attempts to send a request with a body larger than this limit receives an "Invalid Request" error message. If you set this parameter to a zero (the default), there will be no limit imposed. See also client_request_buffer_max_size for an alternative limitation on client uploads which can be configured. DOC_END NAME: client_request_buffer_max_size COMMENT: (bytes) TYPE: b_size_t DEFAULT: 512 KB LOC: Config.maxRequestBufferSize DOC_START This specifies the maximum buffer size of a client request. It prevents squid eating too much memory when somebody uploads a large file. DOC_END NAME: broken_posts IFDEF: USE_HTTP_VIOLATIONS TYPE: acl_access DEFAULT: none DEFAULT_DOC: Obey RFC 2616. LOC: Config.accessList.brokenPosts DOC_START A list of ACL elements which, if matched, causes Squid to send an extra CRLF pair after the body of a PUT/POST request. Some HTTP servers has broken implementations of PUT/POST, and rely on an extra CRLF pair sent by some WWW clients. Quote from RFC2616 section 4.1 on this matter: Note: certain buggy HTTP/1.0 client implementations generate an extra CRLF's after a POST request. To restate what is explicitly forbidden by the BNF, an HTTP/1.1 client must not preface or follow a request with an extra CRLF. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Example: acl buggy_server url_regex ^http://.... broken_posts allow buggy_server DOC_END NAME: adaptation_uses_indirect_client icap_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR&&USE_ADAPTATION DEFAULT: on LOC: Adaptation::Config::use_indirect_client DOC_START Controls whether the indirect client IP address (instead of the direct client IP address) is passed to adaptation services. See also: follow_x_forwarded_for adaptation_send_client_ip DOC_END NAME: via IFDEF: USE_HTTP_VIOLATIONS COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.via DOC_START If set (default), Squid will include a Via header in requests and replies as required by RFC2616. DOC_END NAME: vary_ignore_expire COMMENT: on|off TYPE: onoff LOC: Config.onoff.vary_ignore_expire DEFAULT: off DOC_START Many HTTP servers supporting Vary gives such objects immediate expiry time with no cache-control header when requested by a HTTP/1.0 client. This option enables Squid to ignore such expiry times until HTTP/1.1 is fully implemented. WARNING: If turned on this may eventually cause some varying objects not intended for caching to get cached. DOC_END NAME: request_entities TYPE: onoff LOC: Config.onoff.request_entities DEFAULT: off DOC_START Squid defaults to deny GET and HEAD requests with request entities, as the meaning of such requests are undefined in the HTTP standard even if not explicitly forbidden. Set this directive to on if you have clients which insists on sending request entities in GET or HEAD requests. But be warned that there is server software (both proxies and web servers) which can fail to properly process this kind of request which may make you vulnerable to cache pollution attacks if enabled. DOC_END NAME: request_header_access IFDEF: USE_HTTP_VIOLATIONS TYPE: http_header_access LOC: Config.request_header_access DEFAULT: none DEFAULT_DOC: No limits. DOC_START Usage: request_header_access header_name allow|deny [!]aclname ... WARNING: Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. This option replaces the old 'anonymize_headers' and the older 'http_anonymizer' option with something that is much more configurable. A list of ACLs for each header name allows removal of specific header fields under specific conditions. This option only applies to outgoing HTTP request headers (i.e., headers sent by Squid to the next HTTP hop such as a cache peer or an origin server). The option has no effect during cache hit detection. The equivalent adaptation vectoring point in ICAP terminology is post-cache REQMOD. The option is applied to individual outgoing request header fields. For each request header field F, Squid uses the first qualifying sets of request_header_access rules: 1. Rules with header_name equal to F's name. 2. Rules with header_name 'Other', provided F's name is not on the hard-coded list of commonly used HTTP header names. 3. Rules with header_name 'All'. Within that qualifying rule set, rule ACLs are checked as usual. If ACLs of an "allow" rule match, the header field is allowed to go through as is. If ACLs of a "deny" rule match, the header is removed and request_header_replace is then checked to identify if the removed header has a replacement. If no rules within the set have matching ACLs, the header field is left as is. For example, to achieve the same behavior as the old 'http_anonymizer standard' option, you should use: request_header_access From deny all request_header_access Referer deny all request_header_access User-Agent deny all Or, to reproduce the old 'http_anonymizer paranoid' feature you should use: request_header_access Authorization allow all request_header_access Proxy-Authorization allow all request_header_access Cache-Control allow all request_header_access Content-Length allow all request_header_access Content-Type allow all request_header_access Date allow all request_header_access Host allow all request_header_access If-Modified-Since allow all request_header_access Pragma allow all request_header_access Accept allow all request_header_access Accept-Charset allow all request_header_access Accept-Encoding allow all request_header_access Accept-Language allow all request_header_access Connection allow all request_header_access All deny all HTTP reply headers are controlled with the reply_header_access directive. By default, all headers are allowed (no anonymizing is performed). DOC_END NAME: reply_header_access IFDEF: USE_HTTP_VIOLATIONS TYPE: http_header_access LOC: Config.reply_header_access DEFAULT: none DEFAULT_DOC: No limits. DOC_START Usage: reply_header_access header_name allow|deny [!]aclname ... WARNING: Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. This option only applies to reply headers, i.e., from the server to the client. This is the same as request_header_access, but in the other direction. Please see request_header_access for detailed documentation. For example, to achieve the same behavior as the old 'http_anonymizer standard' option, you should use: reply_header_access Server deny all reply_header_access WWW-Authenticate deny all reply_header_access Link deny all Or, to reproduce the old 'http_anonymizer paranoid' feature you should use: reply_header_access Allow allow all reply_header_access WWW-Authenticate allow all reply_header_access Proxy-Authenticate allow all reply_header_access Cache-Control allow all reply_header_access Content-Encoding allow all reply_header_access Content-Length allow all reply_header_access Content-Type allow all reply_header_access Date allow all reply_header_access Expires allow all reply_header_access Last-Modified allow all reply_header_access Location allow all reply_header_access Pragma allow all reply_header_access Content-Language allow all reply_header_access Retry-After allow all reply_header_access Title allow all reply_header_access Content-Disposition allow all reply_header_access Connection allow all reply_header_access All deny all HTTP request headers are controlled with the request_header_access directive. By default, all headers are allowed (no anonymizing is performed). DOC_END NAME: request_header_replace header_replace IFDEF: USE_HTTP_VIOLATIONS TYPE: http_header_replace LOC: Config.request_header_access DEFAULT: none DOC_START Usage: request_header_replace header_name message Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit) This option allows you to change the contents of headers denied with request_header_access above, by replacing them with some fixed string. This only applies to request headers, not reply headers. By default, headers are removed if denied. DOC_END NAME: reply_header_replace IFDEF: USE_HTTP_VIOLATIONS TYPE: http_header_replace LOC: Config.reply_header_access DEFAULT: none DOC_START Usage: reply_header_replace header_name message Example: reply_header_replace Server Foo/1.0 This option allows you to change the contents of headers denied with reply_header_access above, by replacing them with some fixed string. This only applies to reply headers, not request headers. By default, headers are removed if denied. DOC_END NAME: request_header_add TYPE: HeaderWithAclList LOC: Config.request_header_add DEFAULT: none DOC_START Usage: request_header_add field-name field-value [ acl ... ] Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all This option adds header fields to outgoing HTTP requests (i.e., request headers sent by Squid to the next HTTP hop such as a cache peer or an origin server). The option has no effect during cache hit detection. The equivalent adaptation vectoring point in ICAP terminology is post-cache REQMOD. Field-name is a token specifying an HTTP header name. If a standard HTTP header name is used, Squid does not check whether the new header conflicts with any existing headers or violates HTTP rules. If the request to be modified already contains a field with the same name, the old field is preserved but the header field values are not merged. Field-value is either a token or a quoted string. If quoted string format is used, then the surrounding quotes are removed while escape sequences and %macros are processed. One or more Squid ACLs may be specified to restrict header injection to matching requests. As always in squid.conf, all ACLs in the ACL list must be satisfied for the insertion to happen. The request_header_add supports fast ACLs only. See also: reply_header_add. DOC_END NAME: reply_header_add TYPE: HeaderWithAclList LOC: Config.reply_header_add DEFAULT: none DOC_START Usage: reply_header_add field-name field-value [ acl ... ] Example: reply_header_add X-Client-CA "CA=%ssl::>cert_issuer" all This option adds header fields to outgoing HTTP responses (i.e., response headers delivered by Squid to the client). This option has no effect on cache hit detection. The equivalent adaptation vectoring point in ICAP terminology is post-cache RESPMOD. This option does not apply to successful CONNECT replies. Field-name is a token specifying an HTTP header name. If a standard HTTP header name is used, Squid does not check whether the new header conflicts with any existing headers or violates HTTP rules. If the response to be modified already contains a field with the same name, the old field is preserved but the header field values are not merged. Field-value is either a token or a quoted string. If quoted string format is used, then the surrounding quotes are removed while escape sequences and %macros are processed. One or more Squid ACLs may be specified to restrict header injection to matching responses. As always in squid.conf, all ACLs in the ACL list must be satisfied for the insertion to happen. The reply_header_add option supports fast ACLs only. See also: request_header_add. DOC_END NAME: note TYPE: note LOC: Config.notes DEFAULT: none DOC_START This option used to log custom information about the master transaction. For example, an admin may configure Squid to log which "user group" the transaction belongs to, where "user group" will be determined based on a set of ACLs and not [just] authentication information. Values of key/value pairs can be logged using %{key}note macros: note key value acl ... logformat myFormat ... %{key}note ... This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: relaxed_header_parser COMMENT: on|off|warn TYPE: tristate LOC: Config.onoff.relaxed_header_parser DEFAULT: on DOC_START In the default "on" setting Squid accepts certain forms of non-compliant HTTP messages where it is unambiguous what the sending application intended even if the message is not correctly formatted. The messages is then normalized to the correct form when forwarded by Squid. If set to "warn" then a warning will be emitted in cache.log each time such HTTP error is encountered. If set to "off" then such HTTP errors will cause the request or response to be rejected. DOC_END NAME: collapsed_forwarding COMMENT: (on|off) TYPE: onoff LOC: Config.onoff.collapsed_forwarding DEFAULT: off DOC_START This option controls whether Squid is allowed to merge multiple potentially cachable requests for the same URI before Squid knows whether the response is going to be cachable. When enabled, instead of forwarding each concurrent request for the same URL, Squid just sends the first of them. The other, so called "collapsed" requests, wait for the response to the first request and, if it happens to be cachable, use that response. Here, "concurrent requests" means "received after the first request headers were parsed and before the corresponding response headers were parsed". This feature is disabled by default: enabling collapsed forwarding needlessly delays forwarding requests that look cachable (when they are collapsed) but then need to be forwarded individually anyway because they end up being for uncachable content. However, in some cases, such as acceleration of highly cachable content with periodic or grouped expiration times, the gains from collapsing [large volumes of simultaneous refresh requests] outweigh losses from such delays. Squid collapses two kinds of requests: regular client requests received on one of the listening ports and internal "cache revalidation" requests which are triggered by those regular requests hitting a stale cached object. Revalidation collapsing is currently disabled for Squid instances containing SMP-aware disk or memory caches and for Vary-controlled cached objects. DOC_END NAME: collapsed_forwarding_access TYPE: acl_access DEFAULT: none DEFAULT_DOC: Requests may be collapsed if collapsed_forwarding is on. LOC: Config.accessList.collapsedForwardingAccess DOC_START Use this directive to restrict collapsed forwarding to a subset of eligible requests. The directive is checked for regular HTTP requests, internal revalidation requests, and HTCP/ICP requests. collapsed_forwarding_access allow|deny [!]aclname ... This directive cannot force collapsing. It has no effect on collapsing unless collapsed_forwarding is 'on', and all other collapsing preconditions are satisfied. * A denied request will not collapse, and future transactions will not collapse on it (even if they are allowed to collapse). * An allowed request may collapse, or future transactions may collapse on it (provided they are allowed to collapse). This directive is evaluated before receiving HTTP response headers and without access to Squid-to-peer connection (if any). Only fast ACLs are supported. See also: collapsed_forwarding. DOC_END NAME: shared_transient_entries_limit collapsed_forwarding_shared_entries_limit COMMENT: (number of entries) TYPE: int64_t LOC: Config.shared_transient_entries_limit DEFAULT: 16384 DOC_START This directive limits the size of a table used for sharing current transaction information among SMP workers. A table entry stores meta information about a single cache entry being delivered to Squid client(s) by one or more SMP workers. A single table entry consumes less than 128 shared memory bytes. The limit should be significantly larger than the number of concurrent non-collapsed cachable responses leaving Squid. For a cache that handles less than 5000 concurrent requests, the default setting of 16384 should be plenty. Using excessively large values wastes shared memory. Limiting the table size too much results in hash collisions, leading to lower hit ratio and missed SMP request collapsing opportunities: Transactions left without a table entry cannot cache their responses and are invisible to other concurrent requests for the same resource. A zero limit is allowed but unsupported. A positive small limit lowers hit ratio, but zero limit disables a lot of essential synchronization among SMP workers, leading to HTTP violations (e.g., stale hit responses). It also disables shared collapsed forwarding: A worker becomes unable to collapse its requests on transactions in other workers, resulting in more trips to the origin server and more cache thrashing. DOC_END COMMENT_START TIMEOUTS ----------------------------------------------------------------------------- COMMENT_END NAME: forward_timeout COMMENT: time-units TYPE: time_t LOC: Config.Timeout.forward DEFAULT: 4 minutes DOC_START This parameter specifies how long Squid should at most attempt in finding a forwarding path for the request before giving up. DOC_END NAME: connect_timeout COMMENT: time-units TYPE: time_t LOC: Config.Timeout.connect DEFAULT: 1 minute DOC_START This parameter specifies how long to wait for the TCP connect to the requested server or peer to complete before Squid should attempt to find another path where to forward the request. DOC_END NAME: peer_connect_timeout COMMENT: time-units TYPE: time_t LOC: Config.Timeout.peer_connect DEFAULT: 30 seconds DOC_START This parameter specifies how long to wait for a pending TCP connection to a peer cache. The default is 30 seconds. You may also set different timeout values for individual neighbors with the 'connect-timeout' option on a 'cache_peer' line. DOC_END NAME: read_timeout COMMENT: time-units TYPE: time_t LOC: Config.Timeout.read DEFAULT: 15 minutes DOC_START Applied on peer server connections. After each successful read(), the timeout will be extended by this amount. If no data is read again after this amount of time, the request is aborted and logged with ERR_READ_TIMEOUT. The default is 15 minutes. DOC_END NAME: write_timeout COMMENT: time-units TYPE: time_t LOC: Config.Timeout.write DEFAULT: 15 minutes DOC_START This timeout is tracked for all connections that have data available for writing and are waiting for the socket to become ready. After each successful write, the timeout is extended by the configured amount. If Squid has data to write but the connection is not ready for the configured duration, the transaction associated with the connection is terminated. The default is 15 minutes. DOC_END NAME: request_timeout TYPE: time_t LOC: Config.Timeout.request DEFAULT: 5 minutes DOC_START How long to wait for complete HTTP request headers after initial connection establishment. DOC_END NAME: request_start_timeout TYPE: time_t LOC: Config.Timeout.request_start_timeout DEFAULT: 5 minutes DOC_START How long to wait for the first request byte after initial connection establishment. DOC_END NAME: client_idle_pconn_timeout persistent_request_timeout TYPE: time_t LOC: Config.Timeout.clientIdlePconn DEFAULT: 2 minutes DOC_START How long to wait for the next HTTP request on a persistent client connection after the previous request completes. DOC_END NAME: ftp_client_idle_timeout TYPE: time_t LOC: Config.Timeout.ftpClientIdle DEFAULT: 30 minutes DOC_START How long to wait for an FTP request on a connection to Squid ftp_port. Many FTP clients do not deal with idle connection closures well, necessitating a longer default timeout than client_idle_pconn_timeout used for incoming HTTP requests. DOC_END NAME: client_lifetime COMMENT: time-units TYPE: time_t LOC: Config.Timeout.lifetime DEFAULT: 1 day DOC_START The maximum amount of time a client (browser) is allowed to remain connected to the cache process. This protects the Cache from having a lot of sockets (and hence file descriptors) tied up in a CLOSE_WAIT state from remote clients that go away without properly shutting down (either because of a network failure or because of a poor client implementation). The default is one day, 1440 minutes. NOTE: The default value is intended to be much larger than any client would ever need to be connected to your cache. You should probably change client_lifetime only as a last resort. If you seem to have many client connections tying up filedescriptors, we recommend first tuning the read_timeout, request_timeout, persistent_request_timeout and quick_abort values. DOC_END NAME: pconn_lifetime COMMENT: time-units TYPE: time_t LOC: Config.Timeout.pconnLifetime DEFAULT: 0 seconds DOC_START Desired maximum lifetime of a persistent connection. When set, Squid will close a now-idle persistent connection that exceeded configured lifetime instead of moving the connection into the idle connection pool (or equivalent). No effect on ongoing/active transactions. Connection lifetime is the time period from the connection acceptance or opening time until "now". This limit is useful in environments with long-lived connections where Squid configuration or environmental factors change during a single connection lifetime. If unrestricted, some connections may last for hours and even days, ignoring those changes that should have affected their behavior or their existence. Currently, a new lifetime value supplied via Squid reconfiguration has no effect on already idle connections unless they become busy. When set to '0' this limit is not used. DOC_END NAME: half_closed_clients TYPE: onoff LOC: Config.onoff.half_closed_clients DEFAULT: off DOC_START Some clients may shutdown the sending side of their TCP connections, while leaving their receiving sides open. Sometimes, Squid can not tell the difference between a half-closed and a fully-closed TCP connection. By default, Squid will immediately close client connections when read(2) returns "no more data to read." Change this option to 'on' and Squid will keep open connections until a read(2) or write(2) on the socket returns an error. This may show some benefits for reverse proxies. But if not it is recommended to leave OFF. DOC_END NAME: server_idle_pconn_timeout pconn_timeout TYPE: time_t LOC: Config.Timeout.serverIdlePconn DEFAULT: 1 minute DOC_START Timeout for idle persistent connections to servers and other proxies. DOC_END NAME: ident_timeout TYPE: time_t IFDEF: USE_IDENT LOC: Ident::TheConfig.timeout DEFAULT: 10 seconds DOC_START Maximum time to wait for IDENT lookups to complete. If this is too high, and you enabled IDENT lookups from untrusted users, you might be susceptible to denial-of-service by having many ident requests going at once. DOC_END NAME: shutdown_lifetime COMMENT: time-units TYPE: time_t LOC: Config.shutdownLifetime DEFAULT: 30 seconds DOC_START When SIGTERM or SIGHUP is received, the cache is put into "shutdown pending" mode until all active sockets are closed. This value is the lifetime to set for all open descriptors during shutdown mode. Any active clients after this many seconds will receive a 'timeout' message. DOC_END COMMENT_START ADMINISTRATIVE PARAMETERS ----------------------------------------------------------------------------- COMMENT_END NAME: cache_mgr TYPE: string DEFAULT: webmaster LOC: Config.adminEmail DOC_START Email-address of local cache manager who will receive mail if the cache dies. The default is "webmaster". DOC_END NAME: mail_from TYPE: string DEFAULT: none LOC: Config.EmailFrom DOC_START From: email-address for mail sent when the cache dies. The default is to use 'squid@unique_hostname'. See also: unique_hostname directive. DOC_END NAME: mail_program TYPE: eol DEFAULT: mail LOC: Config.EmailProgram DOC_START Email program used to send mail if the cache dies. The default is "mail". The specified program must comply with the standard Unix mail syntax: mail-program recipient < mailfile Optional command line options can be specified. DOC_END NAME: cache_effective_user TYPE: string DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@ LOC: Config.effectiveUser DOC_START If you start Squid as root, it will change its effective/real UID/GID to the user specified below. The default is to change to UID of @DEFAULT_CACHE_EFFECTIVE_USER@. see also; cache_effective_group DOC_END NAME: cache_effective_group TYPE: string DEFAULT: none DEFAULT_DOC: Use system group memberships of the cache_effective_user account LOC: Config.effectiveGroup DOC_START Squid sets the GID to the effective user's default group ID (taken from the password file) and supplementary group list from the groups membership. If you want Squid to run with a specific GID regardless of the group memberships of the effective user then set this to the group (or GID) you want Squid to run as. When set all other group privileges of the effective user are ignored and only this GID is effective. If Squid is not started as root the user starting Squid MUST be member of the specified group. This option is not recommended by the Squid Team. Our preference is for administrators to configure a secure user account for squid with UID/GID matching system policies. DOC_END NAME: httpd_suppress_version_string COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.httpd_suppress_version_string DOC_START Suppress Squid version string info in HTTP headers and HTML error pages. DOC_END NAME: visible_hostname TYPE: string LOC: Config.visibleHostname DEFAULT: none DEFAULT_DOC: Automatically detect the system host name DOC_START If you want to present a special hostname in error messages, etc, define this. Otherwise, the return value of gethostname() will be used. If you have multiple caches in a cluster and get errors about IP-forwarding you must set them to have individual names with this setting. DOC_END NAME: unique_hostname TYPE: string LOC: Config.uniqueHostname DEFAULT: none DEFAULT_DOC: Copy the value from visible_hostname DOC_START If you want to have multiple machines with the same 'visible_hostname' you must give each machine a different 'unique_hostname' so forwarding loops can be detected. DOC_END NAME: hostname_aliases TYPE: wordlist LOC: Config.hostnameAliases DEFAULT: none DOC_START A list of other DNS names your cache has. DOC_END NAME: umask TYPE: int LOC: Config.umask DEFAULT: 027 DOC_START Minimum umask which should be enforced while the proxy is running, in addition to the umask set at startup. For a traditional octal representation of umasks, start your value with 0. DOC_END COMMENT_START OPTIONS FOR THE CACHE REGISTRATION SERVICE ----------------------------------------------------------------------------- This section contains parameters for the (optional) cache announcement service. This service is provided to help cache administrators locate one another in order to join or create cache hierarchies. An 'announcement' message is sent (via UDP) to the registration service by Squid. By default, the announcement message is NOT SENT unless you enable it with 'announce_period' below. The announcement message includes your hostname, plus the following information from this configuration file: http_port icp_port cache_mgr All current information is processed regularly and made available on the Web at http://www.ircache.net/Cache/Tracker/. COMMENT_END NAME: announce_period TYPE: time_t LOC: Config.Announce.period DEFAULT: 0 DEFAULT_DOC: Announcement messages disabled. DOC_START This is how frequently to send cache announcements. To enable announcing your cache, just set an announce period. Example: announce_period 1 day DOC_END NAME: announce_host TYPE: string DEFAULT: tracker.ircache.net LOC: Config.Announce.host DOC_START Set the hostname where announce registration messages will be sent. See also announce_port and announce_file DOC_END NAME: announce_file TYPE: string DEFAULT: none LOC: Config.Announce.file DOC_START The contents of this file will be included in the announce registration messages. DOC_END NAME: announce_port TYPE: u_short DEFAULT: 3131 LOC: Config.Announce.port DOC_START Set the port where announce registration messages will be sent. See also announce_host and announce_file DOC_END COMMENT_START HTTPD-ACCELERATOR OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: httpd_accel_surrogate_id TYPE: string DEFAULT: none DEFAULT_DOC: visible_hostname is used if no specific ID is set. LOC: Config.Accel.surrogate_id DOC_START Surrogates (http://www.esi.org/architecture_spec_1.0.html) need an identification token to allow control targeting. Because a farm of surrogates may all perform the same tasks, they may share an identification token. When the surrogate is a reverse-proxy, this ID is also used as cdn-id for CDN-Loop detection (RFC 8586). DOC_END NAME: http_accel_surrogate_remote COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.surrogate_is_remote DOC_START Remote surrogates (such as those in a CDN) honour the header "Surrogate-Control: no-store-remote". Set this to on to have squid behave as a remote surrogate. DOC_END NAME: esi_parser IFDEF: USE_SQUID_ESI COMMENT: libxml2|expat TYPE: string LOC: ESIParser::Type DEFAULT: auto DEFAULT_DOC: Selects libxml2 if available at ./configure time or libexpat otherwise. DOC_START Selects the XML parsing library to use when interpreting responses with Edge Side Includes. To disable ESI handling completely, ./configure Squid with --disable-esi. DOC_END COMMENT_START DELAY POOL PARAMETERS ----------------------------------------------------------------------------- COMMENT_END NAME: delay_pools TYPE: delay_pool_count DEFAULT: 0 IFDEF: USE_DELAY_POOLS LOC: Config.Delay DOC_START This represents the number of delay pools to be used. For example, if you have one class 2 delay pool and one class 3 delays pool, you have a total of 2 delay pools. See also delay_parameters, delay_class, delay_access for pool configuration details. DOC_END NAME: delay_class TYPE: delay_pool_class DEFAULT: none IFDEF: USE_DELAY_POOLS LOC: Config.Delay DOC_START This defines the class of each delay pool. There must be exactly one delay_class line for each delay pool. For example, to define two delay pools, one of class 2 and one of class 3, the settings above and here would be: Example: delay_pools 4 # 4 delay pools delay_class 1 2 # pool 1 is a class 2 pool delay_class 2 3 # pool 2 is a class 3 pool delay_class 3 4 # pool 3 is a class 4 pool delay_class 4 5 # pool 4 is a class 5 pool The delay pool classes are: class 1 Everything is limited by a single aggregate bucket. class 2 Everything is limited by a single aggregate bucket as well as an "individual" bucket chosen from bits 25 through 32 of the IPv4 address. class 3 Everything is limited by a single aggregate bucket as well as a "network" bucket chosen from bits 17 through 24 of the IP address and a "individual" bucket chosen from bits 17 through 32 of the IPv4 address. class 4 Everything in a class 3 delay pool, with an additional limit on a per user basis. This only takes effect if the username is established in advance - by forcing authentication in your http_access rules. class 5 Requests are grouped according their tag (see external_acl's tag= reply). Each pool also requires a delay_parameters directive to configure the pool size and speed limits used whenever the pool is applied to a request. Along with a set of delay_access directives to determine when it is used. NOTE: If an IP address is a.b.c.d -> bits 25 through 32 are "d" -> bits 17 through 24 are "c" -> bits 17 through 32 are "c * 256 + d" NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. See also delay_parameters and delay_access. DOC_END NAME: delay_access TYPE: delay_pool_access DEFAULT: none DEFAULT_DOC: Deny using the pool, unless allow rules exist in squid.conf for the pool. IFDEF: USE_DELAY_POOLS LOC: Config.Delay DOC_START This is used to determine which delay pool a request falls into. delay_access is sorted per pool and the matching starts with pool 1, then pool 2, ..., and finally pool N. The first delay pool where the request is allowed is selected for the request. If it does not allow the request to any pool then the request is not delayed (default). For example, if you want some_big_clients in delay pool 1 and lotsa_little_clients in delay pool 2: delay_access 1 allow some_big_clients delay_access 1 deny all delay_access 2 allow lotsa_little_clients delay_access 2 deny all delay_access 3 allow authenticated_clients See also delay_parameters and delay_class. DOC_END NAME: delay_parameters TYPE: delay_pool_rates DEFAULT: none IFDEF: USE_DELAY_POOLS LOC: Config.Delay DOC_START This defines the parameters for a delay pool. Each delay pool has a number of "buckets" associated with it, as explained in the description of delay_class. For a class 1 delay pool, the syntax is: delay_class pool 1 delay_parameters pool aggregate For a class 2 delay pool: delay_class pool 2 delay_parameters pool aggregate individual For a class 3 delay pool: delay_class pool 3 delay_parameters pool aggregate network individual For a class 4 delay pool: delay_class pool 4 delay_parameters pool aggregate network individual user For a class 5 delay pool: delay_class pool 5 delay_parameters pool tagrate The option variables are: pool a pool number - ie, a number between 1 and the number specified in delay_pools as used in delay_class lines. aggregate the speed limit parameters for the aggregate bucket (class 1, 2, 3). individual the speed limit parameters for the individual buckets (class 2, 3). network the speed limit parameters for the network buckets (class 3). user the speed limit parameters for the user buckets (class 4). tagrate the speed limit parameters for the tag buckets (class 5). A pair of delay parameters is written restore/maximum, where restore is the number of bytes (not bits - modem and network speeds are usually quoted in bits) per second placed into the bucket, and maximum is the maximum number of bytes which can be in the bucket at any time. There must be one delay_parameters line for each delay pool. For example, if delay pool number 1 is a class 2 delay pool as in the above example, and is being used to strictly limit each host to 64Kbit/sec (plus overheads), with no overall limit, the line is: delay_parameters 1 none 8000/8000 Note that 8 x 8K Byte/sec -> 64K bit/sec. Note that the word 'none' is used to represent no limit. And, if delay pool number 2 is a class 3 delay pool as in the above example, and you want to limit it to a total of 256Kbit/sec (strict limit) with each 8-bit network permitted 64Kbit/sec (strict limit) and each individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits to permit a decent web page to be downloaded at a decent speed (if the network is not being limited due to overuse) but slow down large downloads more significantly: delay_parameters 2 32000/32000 8000/8000 600/8000 Note that 8 x 32K Byte/sec -> 256K bit/sec. 8 x 8K Byte/sec -> 64K bit/sec. 8 x 600 Byte/sec -> 4800 bit/sec. Finally, for a class 4 delay pool as in the example - each user will be limited to 128Kbits/sec no matter how many workstations they are logged into.: delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000 See also delay_class and delay_access. DOC_END NAME: delay_initial_bucket_level COMMENT: (percent, 0-100) TYPE: u_short DEFAULT: 50 IFDEF: USE_DELAY_POOLS LOC: Config.Delay.initial DOC_START The initial bucket percentage is used to determine how much is put in each bucket when squid starts, is reconfigured, or first notices a host accessing it (in class 2 and class 3, individual hosts and networks only have buckets associated with them once they have been "seen" by squid). DOC_END COMMENT_START CLIENT DELAY POOL PARAMETERS ----------------------------------------------------------------------------- COMMENT_END NAME: client_delay_pools TYPE: client_delay_pool_count DEFAULT: 0 IFDEF: USE_DELAY_POOLS LOC: Config.ClientDelay DOC_START This option specifies the number of client delay pools used. It must preceed other client_delay_* options. Example: client_delay_pools 2 See also client_delay_parameters and client_delay_access. DOC_END NAME: client_delay_initial_bucket_level COMMENT: (percent, 0-no_limit) TYPE: u_short DEFAULT: 50 IFDEF: USE_DELAY_POOLS LOC: Config.ClientDelay.initial DOC_START This option determines the initial bucket size as a percentage of max_bucket_size from client_delay_parameters. Buckets are created at the time of the "first" connection from the matching IP. Idle buckets are periodically deleted up. You can specify more than 100 percent but note that such "oversized" buckets are not refilled until their size goes down to max_bucket_size from client_delay_parameters. Example: client_delay_initial_bucket_level 50 DOC_END NAME: client_delay_parameters TYPE: client_delay_pool_rates DEFAULT: none IFDEF: USE_DELAY_POOLS LOC: Config.ClientDelay DOC_START This option configures client-side bandwidth limits using the following format: client_delay_parameters pool speed_limit max_bucket_size pool is an integer ID used for client_delay_access matching. speed_limit is bytes added to the bucket per second. max_bucket_size is the maximum size of a bucket, enforced after any speed_limit additions. Please see the delay_parameters option for more information and examples. Example: client_delay_parameters 1 1024 2048 client_delay_parameters 2 51200 16384 See also client_delay_access. DOC_END NAME: client_delay_access TYPE: client_delay_pool_access DEFAULT: none DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool. IFDEF: USE_DELAY_POOLS LOC: Config.ClientDelay DOC_START This option determines the client-side delay pool for the request: client_delay_access pool_ID allow|deny acl_name All client_delay_access options are checked in their pool ID order, starting with pool 1. The first checked pool with allowed request is selected for the request. If no ACL matches or there are no client_delay_access options, the request bandwidth is not limited. The ACL-selected pool is then used to find the client_delay_parameters for the request. Client-side pools are not used to aggregate clients. Clients are always aggregated based on their source IP addresses (one bucket per source IP). This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Additionally, only the client TCP connection details are available. ACLs testing HTTP properties will not work. Please see delay_access for more examples. Example: client_delay_access 1 allow low_rate_network client_delay_access 2 allow vips_network See also client_delay_parameters and client_delay_pools. DOC_END NAME: response_delay_pool TYPE: response_delay_pool_parameters DEFAULT: none IFDEF: USE_DELAY_POOLS LOC: Config.MessageDelay DOC_START This option configures client response bandwidth limits using the following format: response_delay_pool name [option=value] ... name the response delay pool name available options: individual-restore The speed limit of an individual bucket(bytes/s). To be used in conjunction with 'individual-maximum'. individual-maximum The maximum number of bytes which can be placed into the individual bucket. To be used in conjunction with 'individual-restore'. aggregate-restore The speed limit for the aggregate bucket(bytes/s). To be used in conjunction with 'aggregate-maximum'. aggregate-maximum The maximum number of bytes which can be placed into the aggregate bucket. To be used in conjunction with 'aggregate-restore'. initial-bucket-level The initial bucket size as a percentage of individual-maximum. Individual and(or) aggregate bucket options may not be specified, meaning no individual and(or) aggregate speed limitation. See also response_delay_pool_access and delay_parameters for terminology details. DOC_END NAME: response_delay_pool_access TYPE: response_delay_pool_access DEFAULT: none DEFAULT_DOC: Deny use of the pool, unless allow rules exist in squid.conf for the pool. IFDEF: USE_DELAY_POOLS LOC: Config.MessageDelay DOC_START Determines whether a specific named response delay pool is used for the transaction. The syntax for this directive is: response_delay_pool_access pool_name allow|deny acl_name All response_delay_pool_access options are checked in the order they appear in this configuration file. The first rule with a matching ACL wins. If (and only if) an "allow" rule won, Squid assigns the response to the corresponding named delay pool. DOC_END COMMENT_START WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: wccp_router TYPE: address LOC: Config.Wccp.router DEFAULT: any_addr DEFAULT_DOC: WCCP disabled. IFDEF: USE_WCCP DOC_START Use this option to define your WCCP ``home'' router for Squid. wccp_router supports a single WCCP(v1) router wccp2_router supports multiple WCCPv2 routers only one of the two may be used at the same time and defines which version of WCCP to use. DOC_END NAME: wccp2_router TYPE: IpAddress_list LOC: Config.Wccp2.router DEFAULT: none DEFAULT_DOC: WCCPv2 disabled. IFDEF: USE_WCCPv2 DOC_START Use this option to define your WCCP ``home'' router for Squid. wccp_router supports a single WCCP(v1) router wccp2_router supports multiple WCCPv2 routers only one of the two may be used at the same time and defines which version of WCCP to use. DOC_END NAME: wccp_version TYPE: int LOC: Config.Wccp.version DEFAULT: 4 IFDEF: USE_WCCP DOC_START This directive is only relevant if you need to set up WCCP(v1) to some very old and end-of-life Cisco routers. In all other setups it must be left unset or at the default setting. It defines an internal version in the WCCP(v1) protocol, with version 4 being the officially documented protocol. According to some users, Cisco IOS 11.2 and earlier only support WCCP version 3. If you're using that or an earlier version of IOS, you may need to change this value to 3, otherwise do not specify this parameter. DOC_END NAME: wccp2_rebuild_wait TYPE: onoff LOC: Config.Wccp2.rebuildwait DEFAULT: on IFDEF: USE_WCCPv2 DOC_START If this is enabled Squid will wait for the cache dir rebuild to finish before sending the first wccp2 HereIAm packet DOC_END NAME: wccp2_forwarding_method TYPE: wccp2_method LOC: Config.Wccp2.forwarding_method DEFAULT: gre IFDEF: USE_WCCPv2 DOC_START WCCP2 allows the setting of forwarding methods between the router/switch and the cache. Valid values are as follows: gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting) Currently (as of IOS 12.4) cisco routers only support GRE. Cisco switches only support the L2 redirect assignment method. DOC_END NAME: wccp2_return_method TYPE: wccp2_method LOC: Config.Wccp2.return_method DEFAULT: gre IFDEF: USE_WCCPv2 DOC_START WCCP2 allows the setting of return methods between the router/switch and the cache for packets that the cache decides not to handle. Valid values are as follows: gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting) Currently (as of IOS 12.4) cisco routers only support GRE. Cisco switches only support the L2 redirect assignment. If the "ip wccp redirect exclude in" command has been enabled on the cache interface, then it is still safe for the proxy server to use a l2 redirect method even if this option is set to GRE. DOC_END NAME: wccp2_assignment_method TYPE: wccp2_amethod LOC: Config.Wccp2.assignment_method DEFAULT: hash IFDEF: USE_WCCPv2 DOC_START WCCP2 allows the setting of methods to assign the WCCP hash Valid values are as follows: hash - Hash assignment mask - Mask assignment As a general rule, cisco routers support the hash assignment method and cisco switches support the mask assignment method. DOC_END NAME: wccp2_service TYPE: wccp2_service LOC: Config.Wccp2.info DEFAULT_IF_NONE: standard 0 DEFAULT_DOC: Use the 'web-cache' standard service. IFDEF: USE_WCCPv2 DOC_START WCCP2 allows for multiple traffic services. There are two types: "standard" and "dynamic". The standard type defines one service id - http (id 0). The dynamic service ids can be from 51 to 255 inclusive. In order to use a dynamic service id one must define the type of traffic to be redirected; this is done using the wccp2_service_info option. The "standard" type does not require a wccp2_service_info option, just specifying the service id will suffice. MD5 service authentication can be enabled by adding "password=" to the end of this service declaration. Examples: wccp2_service standard 0 # for the 'web-cache' standard service wccp2_service dynamic 80 # a dynamic service type which will be # fleshed out with subsequent options. wccp2_service standard 0 password=foo DOC_END NAME: wccp2_service_info TYPE: wccp2_service_info LOC: Config.Wccp2.info DEFAULT: none IFDEF: USE_WCCPv2 DOC_START Dynamic WCCPv2 services require further information to define the traffic you wish to have diverted. The format is: wccp2_service_info protocol= flags=,.. priority= ports=,.. The relevant WCCPv2 flags: + src_ip_hash, dst_ip_hash + source_port_hash, dst_port_hash + src_ip_alt_hash, dst_ip_alt_hash + src_port_alt_hash, dst_port_alt_hash + ports_source The port list can be one to eight entries. Example: wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source priority=240 ports=80 Note: the service id must have been defined by a previous 'wccp2_service dynamic ' entry. DOC_END NAME: wccp2_weight TYPE: int LOC: Config.Wccp2.weight DEFAULT: 10000 IFDEF: USE_WCCPv2 DOC_START Each cache server gets assigned a set of the destination hash proportional to their weight. DOC_END NAME: wccp_address TYPE: address LOC: Config.Wccp.address DEFAULT: 0.0.0.0 DEFAULT_DOC: Address selected by the operating system. IFDEF: USE_WCCP DOC_START Use this option if you require WCCP(v1) to use a specific interface address. The default behavior is to not bind to any specific address. DOC_END NAME: wccp2_address TYPE: address LOC: Config.Wccp2.address DEFAULT: 0.0.0.0 DEFAULT_DOC: Address selected by the operating system. IFDEF: USE_WCCPv2 DOC_START Use this option if you require WCCPv2 to use a specific interface address. The default behavior is to not bind to any specific address. DOC_END COMMENT_START PERSISTENT CONNECTION HANDLING ----------------------------------------------------------------------------- Also see "pconn_timeout" in the TIMEOUTS section COMMENT_END NAME: client_persistent_connections TYPE: onoff LOC: Config.onoff.client_pconns DEFAULT: on DOC_START Persistent connection support for clients. Squid uses persistent connections (when allowed). You can use this option to disable persistent connections with clients. DOC_END NAME: server_persistent_connections TYPE: onoff LOC: Config.onoff.server_pconns DEFAULT: on DOC_START Persistent connection support for servers. Squid uses persistent connections (when allowed). You can use this option to disable persistent connections with servers. DOC_END NAME: persistent_connection_after_error TYPE: onoff LOC: Config.onoff.error_pconns DEFAULT: on DOC_START With this directive the use of persistent connections after HTTP errors can be disabled. Useful if you have clients who fail to handle errors on persistent connections proper. DOC_END NAME: detect_broken_pconn TYPE: onoff LOC: Config.onoff.detect_broken_server_pconns DEFAULT: off DOC_START Some servers have been found to incorrectly signal the use of HTTP/1.0 persistent connections even on replies not compatible, causing significant delays. This server problem has mostly been seen on redirects. By enabling this directive Squid attempts to detect such broken replies and automatically assume the reply is finished after 10 seconds timeout. DOC_END COMMENT_START CACHE DIGEST OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: digest_generation IFDEF: USE_CACHE_DIGESTS TYPE: onoff LOC: Config.onoff.digest_generation DEFAULT: on DOC_START This controls whether the server will generate a Cache Digest of its contents. By default, Cache Digest generation is enabled if Squid is compiled with --enable-cache-digests defined. DOC_END NAME: digest_bits_per_entry IFDEF: USE_CACHE_DIGESTS TYPE: int LOC: Config.digest.bits_per_entry DEFAULT: 5 DOC_START This is the number of bits of the server's Cache Digest which will be associated with the Digest entry for a given HTTP Method and URL (public key) combination. The default is 5. DOC_END NAME: digest_rebuild_period IFDEF: USE_CACHE_DIGESTS COMMENT: (seconds) TYPE: time_t LOC: Config.digest.rebuild_period DEFAULT: 1 hour DOC_START This is the wait time between Cache Digest rebuilds. DOC_END NAME: digest_rewrite_period COMMENT: (seconds) IFDEF: USE_CACHE_DIGESTS TYPE: time_t LOC: Config.digest.rewrite_period DEFAULT: 1 hour DOC_START This is the wait time between Cache Digest writes to disk. DOC_END NAME: digest_swapout_chunk_size COMMENT: (bytes) TYPE: b_size_t IFDEF: USE_CACHE_DIGESTS LOC: Config.digest.swapout_chunk_size DEFAULT: 4096 bytes DOC_START This is the number of bytes of the Cache Digest to write to disk at a time. It defaults to 4096 bytes (4KB), the Squid default swap page. DOC_END NAME: digest_rebuild_chunk_percentage COMMENT: (percent, 0-100) IFDEF: USE_CACHE_DIGESTS TYPE: int LOC: Config.digest.rebuild_chunk_percentage DEFAULT: 10 DOC_START This is the percentage of the Cache Digest to be scanned at a time. By default it is set to 10% of the Cache Digest. DOC_END COMMENT_START SNMP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: snmp_port TYPE: u_short LOC: Config.Port.snmp DEFAULT: 0 DEFAULT_DOC: SNMP disabled. IFDEF: SQUID_SNMP DOC_START The port number where Squid listens for SNMP requests. To enable SNMP support set this to a suitable port number. Port number 3401 is often used for the Squid SNMP agent. By default it's set to "0" (disabled) Example: snmp_port 3401 DOC_END NAME: snmp_access TYPE: acl_access LOC: Config.accessList.snmp DEFAULT: none DEFAULT_DOC: Deny, unless rules exist in squid.conf. IFDEF: SQUID_SNMP DOC_START Allowing or denying access to the SNMP port. All access to the agent is denied by default. usage: snmp_access allow|deny [!]aclname ... This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Example: snmp_access allow snmppublic localhost snmp_access deny all DOC_END NAME: snmp_incoming_address TYPE: address LOC: Config.Addrs.snmp_incoming DEFAULT: any_addr DEFAULT_DOC: Accept SNMP packets from all machine interfaces. IFDEF: SQUID_SNMP DOC_START Just like 'udp_incoming_address', but for the SNMP port. snmp_incoming_address is used for the SNMP socket receiving messages from SNMP agents. The default snmp_incoming_address is to listen on all available network interfaces. DOC_END NAME: snmp_outgoing_address TYPE: address LOC: Config.Addrs.snmp_outgoing DEFAULT: no_addr DEFAULT_DOC: Use snmp_incoming_address or an address selected by the operating system. IFDEF: SQUID_SNMP DOC_START Just like 'udp_outgoing_address', but for the SNMP port. snmp_outgoing_address is used for SNMP packets returned to SNMP agents. If snmp_outgoing_address is not set it will use the same socket as snmp_incoming_address. Only change this if you want to have SNMP replies sent using another address than where this Squid listens for SNMP queries. NOTE, snmp_incoming_address and snmp_outgoing_address can not have the same value since they both use the same port. DOC_END COMMENT_START ICP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: icp_port udp_port TYPE: u_short DEFAULT: 0 DEFAULT_DOC: ICP disabled. LOC: Config.Port.icp DOC_START The port number where Squid sends and receives ICP queries to and from neighbor caches. The standard UDP port for ICP is 3130. Example: icp_port @DEFAULT_ICP_PORT@ DOC_END NAME: htcp_port IFDEF: USE_HTCP TYPE: u_short DEFAULT: 0 DEFAULT_DOC: HTCP disabled. LOC: Config.Port.htcp DOC_START The port number where Squid sends and receives HTCP queries to and from neighbor caches. To turn it on you want to set it to 4827. Example: htcp_port 4827 DOC_END NAME: log_icp_queries COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.log_udp DOC_START If set, ICP queries are logged to access.log. You may wish do disable this if your ICP load is VERY high to speed things up or to simplify log analysis. DOC_END NAME: udp_incoming_address TYPE: address LOC:Config.Addrs.udp_incoming DEFAULT: any_addr DEFAULT_DOC: Accept packets from all machine interfaces. DOC_START udp_incoming_address is used for UDP packets received from other caches. The default behavior is to not bind to any specific address. Only change this if you want to have all UDP queries received on a specific interface/address. NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS modules. Altering it will affect all of them in the same manner. see also; udp_outgoing_address NOTE, udp_incoming_address and udp_outgoing_address can not have the same value since they both use the same port. DOC_END NAME: udp_outgoing_address TYPE: address LOC: Config.Addrs.udp_outgoing DEFAULT: no_addr DEFAULT_DOC: Use udp_incoming_address or an address selected by the operating system. DOC_START udp_outgoing_address is used for UDP packets sent out to other caches. The default behavior is to not bind to any specific address. Instead it will use the same socket as udp_incoming_address. Only change this if you want to have UDP queries sent using another address than where this Squid listens for UDP queries from other caches. NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS modules. Altering it will affect all of them in the same manner. see also; udp_incoming_address NOTE, udp_incoming_address and udp_outgoing_address can not have the same value since they both use the same port. DOC_END NAME: icp_hit_stale COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.icp_hit_stale DOC_START If you want to return ICP_HIT for stale cache objects, set this option to 'on'. If you have sibling relationships with caches in other administrative domains, this should be 'off'. If you only have sibling relationships with caches under your control, it is probably okay to set this to 'on'. If set to 'on', your siblings should use the option "allow-miss" on their cache_peer lines for connecting to you. DOC_END NAME: minimum_direct_hops TYPE: int DEFAULT: 4 LOC: Config.minDirectHops DOC_START If using the ICMP pinging stuff, do direct fetches for sites which are no more than this many hops away. DOC_END NAME: minimum_direct_rtt COMMENT: (msec) TYPE: int DEFAULT: 400 LOC: Config.minDirectRtt DOC_START If using the ICMP pinging stuff, do direct fetches for sites which are no more than this many rtt milliseconds away. DOC_END NAME: netdb_low TYPE: int DEFAULT: 900 LOC: Config.Netdb.low DOC_START The low water mark for the ICMP measurement database. Note: high watermark controlled by netdb_high directive. These watermarks are counts, not percents. The defaults are (low) 900 and (high) 1000. When the high water mark is reached, database entries will be deleted until the low mark is reached. DOC_END NAME: netdb_high TYPE: int DEFAULT: 1000 LOC: Config.Netdb.high DOC_START The high water mark for the ICMP measurement database. Note: low watermark controlled by netdb_low directive. These watermarks are counts, not percents. The defaults are (low) 900 and (high) 1000. When the high water mark is reached, database entries will be deleted until the low mark is reached. DOC_END NAME: netdb_ping_period TYPE: time_t LOC: Config.Netdb.period DEFAULT: 5 minutes DOC_START The minimum period for measuring a site. There will be at least this much delay between successive pings to the same network. The default is five minutes. DOC_END NAME: query_icmp COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.query_icmp DOC_START If you want to ask your peers to include ICMP data in their ICP replies, enable this option. If your peer has configured Squid (during compilation) with '--enable-icmp' that peer will send ICMP pings to origin server sites of the URLs it receives. If you enable this option the ICP replies from that peer will include the ICMP data (if available). Then, when choosing a parent cache, Squid will choose the parent with the minimal RTT to the origin server. When this happens, the hierarchy field of the access.log will be "CLOSEST_PARENT_MISS". This option is off by default. DOC_END NAME: test_reachability COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.test_reachability DOC_START When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH instead of ICP_MISS if the target host is NOT in the ICMP database, or has a zero RTT. DOC_END NAME: icp_query_timeout COMMENT: (msec) DEFAULT: 0 DEFAULT_DOC: Dynamic detection. TYPE: int LOC: Config.Timeout.icp_query DOC_START Normally Squid will automatically determine an optimal ICP query timeout value based on the round-trip-time of recent ICP queries. If you want to override the value determined by Squid, set this 'icp_query_timeout' to a non-zero value. This value is specified in MILLISECONDS, so, to use a 2-second timeout (the old default), you would write: icp_query_timeout 2000 DOC_END NAME: maximum_icp_query_timeout COMMENT: (msec) DEFAULT: 2000 TYPE: int LOC: Config.Timeout.icp_query_max DOC_START Normally the ICP query timeout is determined dynamically. But sometimes it can lead to very large values (say 5 seconds). Use this option to put an upper limit on the dynamic timeout value. Do NOT use this option to always use a fixed (instead of a dynamic) timeout value. To set a fixed timeout see the 'icp_query_timeout' directive. DOC_END NAME: minimum_icp_query_timeout COMMENT: (msec) DEFAULT: 5 TYPE: int LOC: Config.Timeout.icp_query_min DOC_START Normally the ICP query timeout is determined dynamically. But sometimes it can lead to very small timeouts, even lower than the normal latency variance on your link due to traffic. Use this option to put an lower limit on the dynamic timeout value. Do NOT use this option to always use a fixed (instead of a dynamic) timeout value. To set a fixed timeout see the 'icp_query_timeout' directive. DOC_END NAME: background_ping_rate COMMENT: time-units TYPE: time_t DEFAULT: 10 seconds LOC: Config.backgroundPingRate DOC_START Controls how often the ICP pings are sent to siblings that have background-ping set. DOC_END COMMENT_START MULTICAST ICP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: mcast_groups TYPE: wordlist LOC: Config.mcast_group_list DEFAULT: none DOC_START This tag specifies a list of multicast groups which your server should join to receive multicasted ICP queries. NOTE! Be very careful what you put here! Be sure you understand the difference between an ICP _query_ and an ICP _reply_. This option is to be set only if you want to RECEIVE multicast queries. Do NOT set this option to SEND multicast ICP (use cache_peer for that). ICP replies are always sent via unicast, so this option does not affect whether or not you will receive replies from multicast group members. You must be very careful to NOT use a multicast address which is already in use by another group of caches. If you are unsure about multicast, please read the Multicast chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/). Usage: mcast_groups 239.128.16.128 224.0.1.20 By default, Squid doesn't listen on any multicast groups. DOC_END NAME: mcast_miss_addr IFDEF: MULTICAST_MISS_STREAM TYPE: address LOC: Config.mcast_miss.addr DEFAULT: no_addr DEFAULT_DOC: disabled. DOC_START If you enable this option, every "cache miss" URL will be sent out on the specified multicast address. Do not enable this option unless you are are absolutely certain you understand what you are doing. DOC_END NAME: mcast_miss_ttl IFDEF: MULTICAST_MISS_STREAM TYPE: u_short LOC: Config.mcast_miss.ttl DEFAULT: 16 DOC_START This is the time-to-live value for packets multicasted when multicasting off cache miss URLs is enabled. By default this is set to 'site scope', i.e. 16. DOC_END NAME: mcast_miss_port IFDEF: MULTICAST_MISS_STREAM TYPE: u_short LOC: Config.mcast_miss.port DEFAULT: 3135 DOC_START This is the port number to be used in conjunction with 'mcast_miss_addr'. DOC_END NAME: mcast_miss_encode_key IFDEF: MULTICAST_MISS_STREAM TYPE: string LOC: Config.mcast_miss.encode_key DEFAULT: XXXXXXXXXXXXXXXX DOC_START The URLs that are sent in the multicast miss stream are encrypted. This is the encryption key. DOC_END NAME: mcast_icp_query_timeout COMMENT: (msec) DEFAULT: 2000 TYPE: int LOC: Config.Timeout.mcast_icp_query DOC_START For multicast peers, Squid regularly sends out ICP "probes" to count how many other peers are listening on the given multicast address. This value specifies how long Squid should wait to count all the replies. The default is 2000 msec, or 2 seconds. DOC_END COMMENT_START INTERNAL ICON OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: icon_directory TYPE: string LOC: Config.icons.directory DEFAULT: @DEFAULT_ICON_DIR@ DOC_START Where the icons are stored. These are normally kept in @DEFAULT_ICON_DIR@ DOC_END NAME: global_internal_static TYPE: onoff LOC: Config.onoff.global_internal_static DEFAULT: on DOC_START This directive controls is Squid should intercept all requests for /squid-internal-static/ no matter which host the URL is requesting (default on setting), or if nothing special should be done for such URLs (off setting). The purpose of this directive is to make icons etc work better in complex cache hierarchies where it may not always be possible for all corners in the cache mesh to reach the server generating a directory listing. DOC_END NAME: short_icon_urls TYPE: onoff LOC: Config.icons.use_short_names DEFAULT: on DOC_START If this is enabled Squid will use short URLs for icons. If disabled it will revert to the old behavior of including it's own name and port in the URL. If you run a complex cache hierarchy with a mix of Squid and other proxies you may need to disable this directive. DOC_END COMMENT_START ERROR PAGE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: error_directory TYPE: string LOC: Config.errorDirectory DEFAULT: none DEFAULT_DOC: Send error pages in the clients preferred language DOC_START If you wish to create your own versions of the default error files to customize them to suit your company copy the error/template files to another directory and point this tag at them. WARNING: This option will disable multi-language support on error pages if used. The squid developers are interested in making squid available in a wide variety of languages. If you are making translations for a language that Squid does not currently provide please consider contributing your translation back to the project. http://wiki.squid-cache.org/Translations The squid developers working on translations are happy to supply drop-in translated error files in exchange for any new language contributions. DOC_END NAME: error_default_language IFDEF: USE_ERR_LOCALES TYPE: string LOC: Config.errorDefaultLanguage DEFAULT: none DEFAULT_DOC: Generate English language pages. DOC_START Set the default language which squid will send error pages in if no existing translation matches the clients language preferences. If unset (default) generic English will be used. The squid developers are interested in making squid available in a wide variety of languages. If you are interested in making translations for any language see the squid wiki for details. http://wiki.squid-cache.org/Translations DOC_END NAME: error_log_languages IFDEF: USE_ERR_LOCALES TYPE: onoff LOC: Config.errorLogMissingLanguages DEFAULT: on DOC_START Log to cache.log what languages users are attempting to auto-negotiate for translations. Successful negotiations are not logged. Only failures have meaning to indicate that Squid may need an upgrade of its error page translations. DOC_END NAME: err_page_stylesheet TYPE: string LOC: Config.errorStylesheet DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css DOC_START CSS Stylesheet to pattern the display of Squid default error pages. For information on CSS see http://www.w3.org/Style/CSS/ DOC_END NAME: err_html_text TYPE: eol LOC: Config.errHtmlText DEFAULT: none DOC_START HTML text to include in error messages. Make this a "mailto" URL to your admin address, or maybe just a link to your organizations Web page. To include this in your error messages, you must rewrite the error template files (found in the "errors" directory). Wherever you want the 'err_html_text' line to appear, insert a %L tag in the error template file. DOC_END NAME: email_err_data COMMENT: on|off TYPE: onoff LOC: Config.onoff.emailErrData DEFAULT: on DOC_START If enabled, information about the occurred error will be included in the mailto links of the ERR pages (if %W is set) so that the email body contains the data. Syntax is %w DOC_END NAME: deny_info TYPE: denyinfo LOC: Config.denyInfoList DEFAULT: none DOC_START Usage: deny_info err_page_name acl or deny_info http://... acl or deny_info TCP_RESET acl This can be used to return a ERR_ page for requests which do not pass the 'http_access' rules. Squid remembers the last acl it evaluated in http_access, and if a 'deny_info' line exists for that ACL Squid returns a corresponding error page. The acl is typically the last acl on the http_access deny line which denied access. The exceptions to this rule are: - When Squid needs to request authentication credentials. It's then the first authentication related acl encountered - When none of the http_access lines matches. It's then the last acl processed on the last http_access line. - When the decision to deny access was made by an adaptation service, the acl name is the corresponding eCAP or ICAP service_name. NP: If providing your own custom error pages with error_directory you may also specify them by your custom file name: Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys By defaut Squid will send "403 Forbidden". A different 4xx or 5xx may be specified by prefixing the file name with the code and a colon. e.g. 404:ERR_CUSTOM_ACCESS_DENIED Alternatively you can tell Squid to reset the TCP connection by specifying TCP_RESET. Or you can specify an error URL or URL pattern. The browsers will get redirected to the specified URL after formatting tags have been replaced. Redirect will be done with 302 or 307 according to HTTP/1.1 specs. A different 3xx code may be specified by prefixing the URL. e.g. 303:http://example.com/ URL FORMAT TAGS: %a - username (if available. Password NOT included) %A - Local listening IP address the client connection was connected to %B - FTP path URL %e - Error number %E - Error description %h - Squid hostname %H - Request domain name %i - Client IP Address %M - Request Method %O - Unescaped message result from external ACL helper %o - Message result from external ACL helper %p - Request Port number %P - Request Protocol name %R - Request URL path %T - Timestamp in RFC 1123 format %U - Full canonical URL from client (HTTPS URLs terminate with *) %u - Full canonical URL from client %w - Admin email from squid.conf %x - Error name %% - Literal percent (%) code DOC_END COMMENT_START OPTIONS INFLUENCING REQUEST FORWARDING ----------------------------------------------------------------------------- COMMENT_END NAME: nonhierarchical_direct TYPE: onoff LOC: Config.onoff.nonhierarchical_direct DEFAULT: on DOC_START By default, Squid will send any non-hierarchical requests (not cacheable request type) direct to origin servers. When this is set to "off", Squid will prefer to send these requests to parents. Note that in most configurations, by turning this off you will only add latency to these request without any improvement in global hit ratio. This option only sets a preference. If the parent is unavailable a direct connection to the origin server may still be attempted. To completely prevent direct connections use never_direct. DOC_END NAME: prefer_direct TYPE: onoff LOC: Config.onoff.prefer_direct DEFAULT: off DOC_START Normally Squid tries to use parents for most requests. If you for some reason like it to first try going direct and only use a parent if going direct fails set this to on. By combining nonhierarchical_direct off and prefer_direct on you can set up Squid to use a parent as a backup path if going direct fails. Note: If you want Squid to use parents for all requests see the never_direct directive. prefer_direct only modifies how Squid acts on cacheable requests. DOC_END NAME: cache_miss_revalidate COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.cache_miss_revalidate DOC_START RFC 7232 defines a conditional request mechanism to prevent response objects being unnecessarily transferred over the network. If that mechanism is used by the client and a cache MISS occurs it can prevent new cache entries being created. This option determines whether Squid on cache MISS will pass the client revalidation request to the server or tries to fetch new content for caching. It can be useful while the cache is mostly empty to more quickly have the cache populated by generating non-conditional GETs. When set to 'on' (default), Squid will pass all client If-* headers to the server. This permits server responses without a cacheable payload to be delivered and on MISS no new cache entry is created. When set to 'off' and if the request is cacheable, Squid will remove the clients If-Modified-Since and If-None-Match headers from the request sent to the server. This requests a 200 status response from the server to create a new cache entry with. DOC_END NAME: always_direct TYPE: acl_access LOC: Config.accessList.AlwaysDirect DEFAULT: none DEFAULT_DOC: Prevent any cache_peer being used for this request. DOC_START Usage: always_direct allow|deny [!]aclname ... Here you can use ACL elements to specify requests which should ALWAYS be forwarded by Squid to the origin servers without using any peers. For example, to always directly forward requests for local servers ignoring any parents or siblings you may have use something like: acl local-servers dstdomain my.domain.net always_direct allow local-servers To always forward FTP requests directly, use acl FTP proto FTP always_direct allow FTP NOTE: There is a similar, but opposite option named 'never_direct'. You need to be aware that "always_direct deny foo" is NOT the same thing as "never_direct allow foo". You may need to use a deny rule to exclude a more-specific case of some other rule. Example: acl local-external dstdomain external.foo.net acl local-servers dstdomain .foo.net always_direct deny local-external always_direct allow local-servers NOTE: If your goal is to make the client forward the request directly to the origin server bypassing Squid then this needs to be done in the client configuration. Squid configuration can only tell Squid how Squid should fetch the object. NOTE: This directive is not related to caching. The replies is cached as usual even if you use always_direct. To not cache the replies see the 'cache' directive. This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END NAME: never_direct TYPE: acl_access LOC: Config.accessList.NeverDirect DEFAULT: none DEFAULT_DOC: Allow DNS results to be used for this request. DOC_START Usage: never_direct allow|deny [!]aclname ... never_direct is the opposite of always_direct. Please read the description for always_direct if you have not already. With 'never_direct' you can use ACL elements to specify requests which should NEVER be forwarded directly to origin servers. For example, to force the use of a proxy for all requests, except those in your local domain use something like: acl local-servers dstdomain .foo.net never_direct deny local-servers never_direct allow all or if Squid is inside a firewall and there are local intranet servers inside the firewall use something like: acl local-intranet dstdomain .foo.net acl local-external dstdomain external.foo.net always_direct deny local-external always_direct allow local-intranet never_direct allow all This clause supports both fast and slow acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. DOC_END COMMENT_START ADVANCED NETWORKING OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: incoming_udp_average incoming_icp_average TYPE: int DEFAULT: 6 LOC: Config.comm_incoming.udp.average DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: incoming_tcp_average incoming_http_average TYPE: int DEFAULT: 4 LOC: Config.comm_incoming.tcp.average DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: incoming_dns_average TYPE: int DEFAULT: 4 LOC: Config.comm_incoming.dns.average DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: min_udp_poll_cnt min_icp_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.udp.min_poll DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: min_dns_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.dns.min_poll DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: min_tcp_poll_cnt min_http_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.tcp.min_poll DOC_START Heavy voodoo here. I can't even believe you are reading this. Are you crazy? Don't even think about adjusting these unless you understand the algorithms in comm_select.c first! DOC_END NAME: accept_filter TYPE: string DEFAULT: none LOC: Config.accept_filter DOC_START FreeBSD: The name of an accept(2) filter to install on Squid's listen socket(s). This feature is perhaps specific to FreeBSD and requires support in the kernel. The 'httpready' filter delays delivering new connections to Squid until a full HTTP request has been received. See the accf_http(9) man page for details. The 'dataready' filter delays delivering new connections to Squid until there is some data to process. See the accf_dataready(9) man page for details. Linux: The 'data' filter delays delivering of new connections to Squid until there is some data to process by TCP_ACCEPT_DEFER. You may optionally specify a number of seconds to wait by 'data=N' where N is the number of seconds. Defaults to 30 if not specified. See the tcp(7) man page for details. EXAMPLE: # FreeBSD accept_filter httpready # Linux accept_filter data DOC_END NAME: client_ip_max_connections TYPE: int LOC: Config.client_ip_max_connections DEFAULT: -1 DEFAULT_DOC: No limit. DOC_START Set an absolute limit on the number of connections a single client IP can use. Any more than this and Squid will begin to drop new connections from the client until it closes some links. Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP connections from the client. For finer control use the ACL access controls. Requires client_db to be enabled (the default). WARNING: This may noticably slow down traffic received via external proxies or NAT devices and cause them to rebound error messages back to their clients. DOC_END NAME: tcp_recv_bufsize COMMENT: (bytes) TYPE: b_size_t DEFAULT: 0 bytes DEFAULT_DOC: Use operating system TCP defaults. LOC: Config.tcpRcvBufsz DOC_START Size of receive buffer to set for TCP sockets. Probably just as easy to change your kernel's default. Omit from squid.conf to use the default buffer size. DOC_END COMMENT_START ICAP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: icap_enable TYPE: onoff IFDEF: ICAP_CLIENT COMMENT: on|off LOC: Adaptation::Icap::TheConfig.onoff DEFAULT: off DOC_START If you want to enable the ICAP module support, set this to on. DOC_END NAME: icap_connect_timeout TYPE: time_t DEFAULT: none LOC: Adaptation::Icap::TheConfig.connect_timeout_raw IFDEF: ICAP_CLIENT DOC_START This parameter specifies how long to wait for the TCP connect to the requested ICAP server to complete before giving up and either terminating the HTTP transaction or bypassing the failure. The default for optional services is peer_connect_timeout. The default for essential services is connect_timeout. If this option is explicitly set, its value applies to all services. DOC_END NAME: icap_io_timeout COMMENT: time-units TYPE: time_t DEFAULT: none DEFAULT_DOC: Use read_timeout. LOC: Adaptation::Icap::TheConfig.io_timeout_raw IFDEF: ICAP_CLIENT DOC_START This parameter specifies how long to wait for an I/O activity on an established, active ICAP connection before giving up and either terminating the HTTP transaction or bypassing the failure. DOC_END NAME: icap_service_failure_limit COMMENT: limit [in memory-depth time-units] TYPE: icap_service_failure_limit IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig DEFAULT: 10 DOC_START The limit specifies the number of failures that Squid tolerates when establishing a new TCP connection with an ICAP service. If the number of failures exceeds the limit, the ICAP service is not used for new ICAP requests until it is time to refresh its OPTIONS. A negative value disables the limit. Without the limit, an ICAP service will not be considered down due to connectivity failures between ICAP OPTIONS requests. Squid forgets ICAP service failures older than the specified value of memory-depth. The memory fading algorithm is approximate because Squid does not remember individual errors but groups them instead, splitting the option value into ten time slots of equal length. When memory-depth is 0 and by default this option has no effect on service failure expiration. Squid always forgets failures when updating service settings using an ICAP OPTIONS transaction, regardless of this option setting. For example, # suspend service usage after 10 failures in 5 seconds: icap_service_failure_limit 10 in 5 seconds DOC_END NAME: icap_service_revival_delay TYPE: int IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.service_revival_delay DEFAULT: 180 DOC_START The delay specifies the number of seconds to wait after an ICAP OPTIONS request failure before requesting the options again. The failed ICAP service is considered "down" until fresh OPTIONS are fetched. The actual delay cannot be smaller than the hardcoded minimum delay of 30 seconds. DOC_END NAME: icap_preview_enable TYPE: onoff IFDEF: ICAP_CLIENT COMMENT: on|off LOC: Adaptation::Icap::TheConfig.preview_enable DEFAULT: on DOC_START The ICAP Preview feature allows the ICAP server to handle the HTTP message by looking only at the beginning of the message body or even without receiving the body at all. In some environments, previews greatly speedup ICAP processing. During an ICAP OPTIONS transaction, the server may tell Squid what HTTP messages should be previewed and how big the preview should be. Squid will not use Preview if the server did not request one. To disable ICAP Preview for all ICAP services, regardless of individual ICAP server OPTIONS responses, set this option to "off". Example: icap_preview_enable off DOC_END NAME: icap_preview_size TYPE: int IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.preview_size DEFAULT: -1 DEFAULT_DOC: No preview sent. DOC_START The default size of preview data to be sent to the ICAP server. This value might be overwritten on a per server basis by OPTIONS requests. DOC_END NAME: icap_206_enable TYPE: onoff IFDEF: ICAP_CLIENT COMMENT: on|off LOC: Adaptation::Icap::TheConfig.allow206_enable DEFAULT: on DOC_START 206 (Partial Content) responses is an ICAP extension that allows the ICAP agents to optionally combine adapted and original HTTP message content. The decision to combine is postponed until the end of the ICAP response. Squid supports Partial Content extension by default. Activation of the Partial Content extension is negotiated with each ICAP service during OPTIONS exchange. Most ICAP servers should handle negotation correctly even if they do not support the extension, but some might fail. To disable Partial Content support for all ICAP services and to avoid any negotiation, set this option to "off". Example: icap_206_enable off DOC_END NAME: icap_default_options_ttl TYPE: int IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.default_options_ttl DEFAULT: 60 DOC_START The default TTL value for ICAP OPTIONS responses that don't have an Options-TTL header. DOC_END NAME: icap_persistent_connections TYPE: onoff IFDEF: ICAP_CLIENT COMMENT: on|off LOC: Adaptation::Icap::TheConfig.reuse_connections DEFAULT: on DOC_START Whether or not Squid should use persistent connections to an ICAP server. DOC_END NAME: adaptation_send_client_ip icap_send_client_ip TYPE: onoff IFDEF: USE_ADAPTATION COMMENT: on|off LOC: Adaptation::Config::send_client_ip DEFAULT: off DOC_START If enabled, Squid shares HTTP client IP information with adaptation services. For ICAP, Squid adds the X-Client-IP header to ICAP requests. For eCAP, Squid sets the libecap::metaClientIp transaction option. See also: adaptation_uses_indirect_client DOC_END NAME: adaptation_send_username icap_send_client_username TYPE: onoff IFDEF: USE_ADAPTATION COMMENT: on|off LOC: Adaptation::Config::send_username DEFAULT: off DOC_START This sends authenticated HTTP client username (if available) to the adaptation service. For ICAP, the username value is encoded based on the icap_client_username_encode option and is sent using the header specified by the icap_client_username_header option. DOC_END NAME: icap_client_username_header TYPE: string IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.client_username_header DEFAULT: X-Client-Username DOC_START ICAP request header name to use for adaptation_send_username. DOC_END NAME: icap_client_username_encode TYPE: onoff IFDEF: ICAP_CLIENT COMMENT: on|off LOC: Adaptation::Icap::TheConfig.client_username_encode DEFAULT: off DOC_START Whether to base64 encode the authenticated client username. DOC_END NAME: icap_service TYPE: icap_service_type IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig DEFAULT: none DOC_START Defines a single ICAP service using the following format: icap_service id vectoring_point uri [option ...] id: ID an opaque identifier or name which is used to direct traffic to this specific service. Must be unique among all adaptation services in squid.conf. vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache This specifies at which point of transaction processing the ICAP service should be activated. *_postcache vectoring points are not yet supported. uri: icap://servername:port/servicepath ICAP server and service location. icaps://servername:port/servicepath The "icap:" URI scheme is used for traditional ICAP server and service location (default port is 1344, connections are not encrypted). The "icaps:" URI scheme is for Secure ICAP services that use SSL/TLS-encrypted ICAP connections (by default, on port 11344). ICAP does not allow a single service to handle both REQMOD and RESPMOD transactions. Squid does not enforce that requirement. You can specify services with the same service_url and different vectoring_points. You can even specify multiple identical services as long as their service_names differ. To activate a service, use the adaptation_access directive. To group services, use adaptation_service_chain and adaptation_service_set. Service options are separated by white space. ICAP services support the following name=value options: bypass=on|off|1|0 If set to 'on' or '1', the ICAP service is treated as optional. If the service cannot be reached or malfunctions, Squid will try to ignore any errors and process the message as if the service was not enabled. No all ICAP errors can be bypassed. If set to 0, the ICAP service is treated as essential and all ICAP errors will result in an error page returned to the HTTP client. Bypass is off by default: services are treated as essential. routing=on|off|1|0 If set to 'on' or '1', the ICAP service is allowed to dynamically change the current message adaptation plan by returning a chain of services to be used next. The services are specified using the X-Next-Services ICAP response header value, formatted as a comma-separated list of service names. Each named service should be configured in squid.conf. Other services are ignored. An empty X-Next-Services value results in an empty plan which ends the current adaptation. Dynamic adaptation plan may cross or cover multiple supported vectoring points in their natural processing order. Routing is not allowed by default: the ICAP X-Next-Services response header is ignored. ipv6=on|off Only has effect on split-stack systems. The default on those systems is to use IPv4-only connections. When set to 'on' this option will make Squid use IPv6-only connections to contact this ICAP service. on-overload=block|bypass|wait|force If the service Max-Connections limit has been reached, do one of the following for each new ICAP transaction: * block: send an HTTP error response to the client * bypass: ignore the "over-connected" ICAP service * wait: wait (in a FIFO queue) for an ICAP connection slot * force: proceed, ignoring the Max-Connections limit In SMP mode with N workers, each worker assumes the service connection limit is Max-Connections/N, even though not all workers may use a given service. The default value is "bypass" if service is bypassable, otherwise it is set to "wait". max-conn=number Use the given number as the Max-Connections limit, regardless of the Max-Connections value given by the service, if any. connection-encryption=on|off Determines the ICAP service effect on the connections_encrypted ACL. The default is "on" for Secure ICAP services (i.e., those with the icaps:// service URIs scheme) and "off" for plain ICAP services. Does not affect ICAP connections (e.g., does not turn Secure ICAP on or off). ==== ICAPS / TLS OPTIONS ==== These options are used for Secure ICAP (icaps://....) services only. tls-cert=/path/to/ssl/certificate A client X.509 certificate to use when connecting to this ICAP server. tls-key=/path/to/ssl/key The private key corresponding to the previous tls-cert= option. If tls-key= is not specified tls-cert= is assumed to reference a PEM file containing both the certificate and private key. tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting to this icap server. tls-min-version=1.N The minimum TLS protocol version to permit. To control SSLv3 use the tls-options= parameter. Supported Values: 1.0 (default), 1.1, 1.2 tls-options=... Specify various OpenSSL library options: NO_SSLv3 Disallow the use of SSLv3 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges ALL Enable various bug workarounds suggested as "harmless" by OpenSSL Be warned that this reduces SSL/TLS strength to some attacks. See the OpenSSL SSL_CTX_set_options documentation for a more complete list. Options relevant only to SSLv2 are not supported. tls-cafile= PEM file containing CA certificates to use when verifying the icap server certificate. Use to specify intermediate CA certificate(s) if not sent by the server. Or the full CA chain for the server when using the tls-default-ca=off flag. May be repeated to load multiple files. tls-capath=... A directory containing additional CA certificates to use when verifying the icap server certificate. Requires OpenSSL or LibreSSL. tls-crlfile=... A certificate revocation list file to use when verifying the icap server certificate. tls-flags=... Specify various flags modifying the Squid TLS implementation: DONT_VERIFY_PEER Accept certificates even if they fail to verify. DONT_VERIFY_DOMAIN Don't verify the icap server certificate matches the server name tls-default-ca[=off] Whether to use the system Trusted CAs. Default is ON. tls-domain= The icap server name as advertised in it's certificate. Used for verifying the correctness of the received icap server certificate. If not specified the icap server hostname extracted from ICAP URI will be used. Older icap_service format without optional named parameters is deprecated but supported for backward compatibility. Example: icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0 icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on DOC_END NAME: icap_class TYPE: icap_class_type IFDEF: ICAP_CLIENT LOC: none DEFAULT: none DOC_START This deprecated option was documented to define an ICAP service chain, even though it actually defined a set of similar, redundant services, and the chains were not supported. To define a set of redundant services, please use the adaptation_service_set directive. For service chains, use adaptation_service_chain. DOC_END NAME: icap_access TYPE: icap_access_type IFDEF: ICAP_CLIENT LOC: none DEFAULT: none DOC_START This option is deprecated. Please use adaptation_access, which has the same ICAP functionality, but comes with better documentation, and eCAP support. DOC_END COMMENT_START eCAP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: ecap_enable TYPE: onoff IFDEF: USE_ECAP COMMENT: on|off LOC: Adaptation::Ecap::TheConfig.onoff DEFAULT: off DOC_START Controls whether eCAP support is enabled. DOC_END NAME: ecap_service TYPE: ecap_service_type IFDEF: USE_ECAP LOC: Adaptation::Ecap::TheConfig DEFAULT: none DOC_START Defines a single eCAP service ecap_service id vectoring_point uri [option ...] id: ID an opaque identifier or name which is used to direct traffic to this specific service. Must be unique among all adaptation services in squid.conf. vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache This specifies at which point of transaction processing the eCAP service should be activated. *_postcache vectoring points are not yet supported. uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional Squid uses the eCAP service URI to match this configuration line with one of the dynamically loaded services. Each loaded eCAP service must have a unique URI. Obtain the right URI from the service provider. To activate a service, use the adaptation_access directive. To group services, use adaptation_service_chain and adaptation_service_set. Service options are separated by white space. eCAP services support the following name=value options: bypass=on|off|1|0 If set to 'on' or '1', the eCAP service is treated as optional. If the service cannot be reached or malfunctions, Squid will try to ignore any errors and process the message as if the service was not enabled. No all eCAP errors can be bypassed. If set to 'off' or '0', the eCAP service is treated as essential and all eCAP errors will result in an error page returned to the HTTP client. Bypass is off by default: services are treated as essential. routing=on|off|1|0 If set to 'on' or '1', the eCAP service is allowed to dynamically change the current message adaptation plan by returning a chain of services to be used next. Dynamic adaptation plan may cross or cover multiple supported vectoring points in their natural processing order. Routing is not allowed by default. connection-encryption=on|off Determines the eCAP service effect on the connections_encrypted ACL. Defaults to "on", which does not taint the master transaction w.r.t. that ACL. Does not affect eCAP API calls. Older ecap_service format without optional named parameters is deprecated but supported for backward compatibility. Example: ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on DOC_END NAME: loadable_modules TYPE: wordlist IFDEF: USE_LOADABLE_MODULES LOC: Config.loadable_module_names DEFAULT: none DOC_START Instructs Squid to load the specified dynamic module(s) or activate preloaded module(s). Example: loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so DOC_END COMMENT_START MESSAGE ADAPTATION OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: adaptation_service_set TYPE: adaptation_service_set_type IFDEF: USE_ADAPTATION LOC: none DEFAULT: none DOC_START Configures an ordered set of similar, redundant services. This is useful when hot standby or backup adaptation servers are available. adaptation_service_set set_name service_name1 service_name2 ... The named services are used in the set declaration order. The first applicable adaptation service from the set is used first. The next applicable service is tried if and only if the transaction with the previous service fails and the message waiting to be adapted is still intact. When adaptation starts, broken services are ignored as if they were not a part of the set. A broken service is a down optional service. The services in a set must be attached to the same vectoring point (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD). If all services in a set are optional then adaptation failures are bypassable. If all services in the set are essential, then a transaction failure with one service may still be retried using another service from the set, but when all services fail, the master transaction fails as well. A set may contain a mix of optional and essential services, but that is likely to lead to surprising results because broken services become ignored (see above), making previously bypassable failures fatal. Technically, it is the bypassability of the last failed service that matters. See also: adaptation_access adaptation_service_chain Example: adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup adaptation service_set svcLogger loggerLocal loggerRemote DOC_END NAME: adaptation_service_chain TYPE: adaptation_service_chain_type IFDEF: USE_ADAPTATION LOC: none DEFAULT: none DOC_START Configures a list of complementary services that will be applied one-by-one, forming an adaptation chain or pipeline. This is useful when Squid must perform different adaptations on the same message. adaptation_service_chain chain_name service_name1 svc_name2 ... The named services are used in the chain declaration order. The first applicable adaptation service from the chain is used first. The next applicable service is applied to the successful adaptation results of the previous service in the chain. When adaptation starts, broken services are ignored as if they were not a part of the chain. A broken service is a down optional service. Request satisfaction terminates the adaptation chain because Squid does not currently allow declaration of RESPMOD services at the "reqmod_precache" vectoring point (see icap_service or ecap_service). The services in a chain must be attached to the same vectoring point (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD). A chain may contain a mix of optional and essential services. If an essential adaptation fails (or the failure cannot be bypassed for other reasons), the master transaction fails. Otherwise, the failure is bypassed as if the failed adaptation service was not in the chain. See also: adaptation_access adaptation_service_set Example: adaptation_service_chain svcRequest requestLogger urlFilter leakDetector DOC_END NAME: adaptation_access TYPE: adaptation_access_type IFDEF: USE_ADAPTATION LOC: none DEFAULT: none DEFAULT_DOC: Allow, unless rules exist in squid.conf. DOC_START Sends an HTTP transaction to an ICAP or eCAP adaptation service. adaptation_access service_name allow|deny [!]aclname... adaptation_access set_name allow|deny [!]aclname... At each supported vectoring point, the adaptation_access statements are processed in the order they appear in this configuration file. Statements pointing to the following services are ignored (i.e., skipped without checking their ACL): - services serving different vectoring points - "broken-but-bypassable" services - "up" services configured to ignore such transactions (e.g., based on the ICAP Transfer-Ignore header). When a set_name is used, all services in the set are checked using the same rules, to find the first applicable one. See adaptation_service_set for details. If an access list is checked and there is a match, the processing stops: For an "allow" rule, the corresponding adaptation service is used for the transaction. For a "deny" rule, no adaptation service is activated. It is currently not possible to apply more than one adaptation service at the same vectoring point to the same HTTP transaction. See also: icap_service and ecap_service Example: adaptation_access service_1 allow all DOC_END NAME: adaptation_service_iteration_limit TYPE: int IFDEF: USE_ADAPTATION LOC: Adaptation::Config::service_iteration_limit DEFAULT: 16 DOC_START Limits the number of iterations allowed when applying adaptation services to a message. If your longest adaptation set or chain may have more than 16 services, increase the limit beyond its default value of 16. If detecting infinite iteration loops sooner is critical, make the iteration limit match the actual number of services in your longest adaptation set or chain. Infinite adaptation loops are most likely with routing services. See also: icap_service routing=1 DOC_END NAME: adaptation_masterx_shared_names TYPE: string IFDEF: USE_ADAPTATION LOC: Adaptation::Config::masterx_shared_name DEFAULT: none DOC_START For each master transaction (i.e., the HTTP request and response sequence, including all related ICAP and eCAP exchanges), Squid maintains a table of metadata. The table entries are (name, value) pairs shared among eCAP and ICAP exchanges. The table is destroyed with the master transaction. This option specifies the table entry names that Squid must accept from and forward to the adaptation transactions. An ICAP REQMOD or RESPMOD transaction may set an entry in the shared table by returning an ICAP header field with a name specified in adaptation_masterx_shared_names. An eCAP REQMOD or RESPMOD transaction may set an entry in the shared table by implementing the libecap::visitEachOption() API to provide an option with a name specified in adaptation_masterx_shared_names. Squid will store and forward the set entry to subsequent adaptation transactions within the same master transaction scope. Only one shared entry name is supported at this time. Example: # share authentication information among ICAP services adaptation_masterx_shared_names X-Subscriber-ID DOC_END NAME: adaptation_meta TYPE: note IFDEF: USE_ADAPTATION LOC: Adaptation::Config::metaHeaders DEFAULT: none DOC_START This option allows Squid administrator to add custom ICAP request headers or eCAP options to Squid ICAP requests or eCAP transactions. Use it to pass custom authentication tokens and other transaction-state related meta information to an ICAP/eCAP service. The addition of a meta header is ACL-driven: adaptation_meta name value [!]aclname ... Processing for a given header name stops after the first ACL list match. Thus, it is impossible to add two headers with the same name. If no ACL lists match for a given header name, no such header is added. For example: # do not debug transactions except for those that need debugging adaptation_meta X-Debug 1 needs_debugging # log all transactions except for those that must remain secret adaptation_meta X-Log 1 !keep_secret # mark transactions from users in the "G 1" group adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1 The "value" parameter may be a regular squid.conf token or a "double quoted string". Within the quoted string, use backslash (\) to escape any character, which is currently only useful for escaping backslashes and double quotes. For example, "this string has one backslash (\\) and two \"quotes\"" Used adaptation_meta header values may be logged via %note logformat code. If multiple adaptation_meta headers with the same name are used during master transaction lifetime, the header values are logged in the order they were used and duplicate values are ignored (only the first repeated value will be logged). DOC_END NAME: icap_retry TYPE: acl_access IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.repeat DEFAULT_IF_NONE: deny all DOC_START This ACL determines which retriable ICAP transactions are retried. Transactions that received a complete ICAP response and did not have to consume or produce HTTP bodies to receive that response are usually retriable. icap_retry allow|deny [!]aclname ... Squid automatically retries some ICAP I/O timeouts and errors due to persistent connection race conditions. See also: icap_retry_limit DOC_END NAME: icap_retry_limit TYPE: int IFDEF: ICAP_CLIENT LOC: Adaptation::Icap::TheConfig.repeat_limit DEFAULT: 0 DEFAULT_DOC: No retries are allowed. DOC_START Limits the number of retries allowed. Communication errors due to persistent connection race conditions are unavoidable, automatically retried, and do not count against this limit. See also: icap_retry DOC_END COMMENT_START DNS OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: check_hostnames TYPE: onoff DEFAULT: off LOC: Config.onoff.check_hostnames DOC_START For security and stability reasons Squid can check hostnames for Internet standard RFC compliance. If you want Squid to perform these checks turn this directive on. DOC_END NAME: allow_underscore TYPE: onoff DEFAULT: on LOC: Config.onoff.allow_underscore DOC_START Underscore characters is not strictly allowed in Internet hostnames but nevertheless used by many sites. Set this to off if you want Squid to be strict about the standard. This check is performed only when check_hostnames is set to on. DOC_END NAME: dns_retransmit_interval TYPE: time_msec DEFAULT: 5 seconds LOC: Config.Timeout.idns_retransmit DOC_START Initial retransmit interval for DNS queries. The interval is doubled each time all configured DNS servers have been tried. DOC_END NAME: dns_timeout TYPE: time_msec DEFAULT: 30 seconds LOC: Config.Timeout.idns_query DOC_START DNS Query timeout. If no response is received to a DNS query within this time all DNS servers for the queried domain are assumed to be unavailable. DOC_END NAME: dns_packet_max TYPE: b_ssize_t DEFAULT_DOC: EDNS disabled DEFAULT: none LOC: Config.dns.packet_max DOC_START Maximum number of bytes packet size to advertise via EDNS. Set to "none" to disable EDNS large packet support. For legacy reasons DNS UDP replies will default to 512 bytes which is too small for many responses. EDNS provides a means for Squid to negotiate receiving larger responses back immediately without having to failover with repeat requests. Responses larger than this limit will retain the old behaviour of failover to TCP DNS. Squid has no real fixed limit internally, but allowing packet sizes over 1500 bytes requires network jumbogram support and is usually not necessary. WARNING: The RFC also indicates that some older resolvers will reply with failure of the whole request if the extension is added. Some resolvers have already been identified which will reply with mangled EDNS response on occasion. Usually in response to many-KB jumbogram sizes being advertised by Squid. Squid will currently treat these both as an unable-to-resolve domain even if it would be resolvable without EDNS. DOC_END NAME: dns_defnames COMMENT: on|off TYPE: onoff DEFAULT: off DEFAULT_DOC: Search for single-label domain names is disabled. LOC: Config.onoff.res_defnames DOC_START Normally the RES_DEFNAMES resolver option is disabled (see res_init(3)). This prevents caches in a hierarchy from interpreting single-component hostnames locally. To allow Squid to handle single-component names, enable this option. DOC_END NAME: dns_multicast_local COMMENT: on|off TYPE: onoff DEFAULT: off DEFAULT_DOC: Search for .local and .arpa names is disabled. LOC: Config.onoff.dns_mdns DOC_START When set to on, Squid sends multicast DNS lookups on the local network for domains ending in .local and .arpa. This enables local servers and devices to be contacted in an ad-hoc or zero-configuration network environment. DOC_END NAME: dns_nameservers TYPE: SBufList DEFAULT: none DEFAULT_DOC: Use operating system definitions LOC: Config.dns.nameservers DOC_START Use this if you want to specify a list of DNS name servers (IP addresses) to use instead of those given in your /etc/resolv.conf file. On Windows platforms, if no value is specified here or in the /etc/resolv.conf file, the list of DNS name servers are taken from the Windows registry, both static and dynamic DHCP configurations are supported. Example: dns_nameservers 10.0.0.1 192.172.0.4 DOC_END NAME: hosts_file TYPE: string DEFAULT: @DEFAULT_HOSTS@ LOC: Config.etcHostsPath DOC_START Location of the host-local IP name-address associations database. Most Operating Systems have such a file on different default locations: - Un*X & Linux: /etc/hosts - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts (%SystemRoot% value install default is c:\winnt) - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts (%SystemRoot% value install default is c:\windows) - Windows 9x/Me: %windir%\hosts (%windir% value is usually c:\windows) - Cygwin: /etc/hosts The file contains newline-separated definitions, in the form ip_address_in_dotted_form name [name ...] names are whitespace-separated. Lines beginning with an hash (#) character are comments. The file is checked at startup and upon configuration. If set to 'none', it won't be checked. If append_domain is used, that domain will be added to domain-local (i.e. not containing any dot character) host definitions. DOC_END NAME: append_domain TYPE: string LOC: Config.appendDomain DEFAULT: none DEFAULT_DOC: Use operating system definitions DOC_START Appends local domain name to hostnames without any dots in them. append_domain must begin with a period. Be warned there are now Internet names with no dots in them using only top-domain names, so setting this may cause some Internet sites to become unavailable. Example: append_domain .yourdomain.com DOC_END NAME: ignore_unknown_nameservers TYPE: onoff LOC: Config.onoff.ignore_unknown_nameservers DEFAULT: on DOC_START By default Squid checks that DNS responses are received from the same IP addresses they are sent to. If they don't match, Squid ignores the response and writes a warning message to cache.log. You can allow responses from unknown nameservers by setting this option to 'off'. DOC_END NAME: ipcache_size COMMENT: (number of entries) TYPE: int DEFAULT: 1024 LOC: Config.ipcache.size DOC_START Maximum number of DNS IP cache entries. DOC_END NAME: ipcache_low COMMENT: (percent) TYPE: int DEFAULT: 90 LOC: Config.ipcache.low DOC_NONE NAME: ipcache_high COMMENT: (percent) TYPE: int DEFAULT: 95 LOC: Config.ipcache.high DOC_START The size, low-, and high-water marks for the IP cache. DOC_END NAME: fqdncache_size COMMENT: (number of entries) TYPE: int DEFAULT: 1024 LOC: Config.fqdncache.size DOC_START Maximum number of FQDN cache entries. DOC_END COMMENT_START MISCELLANEOUS ----------------------------------------------------------------------------- COMMENT_END NAME: configuration_includes_quoted_values COMMENT: on|off TYPE: configuration_includes_quoted_values DEFAULT: off LOC: ConfigParser::RecognizeQuotedValues DOC_START If set, Squid will recognize each "quoted string" after a configuration directive as a single parameter. The quotes are stripped before the parameter value is interpreted or used. See "Values with spaces, quotes, and other special characters" section for more details. DOC_END NAME: memory_pools COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.mem_pools DOC_START If set, Squid will keep pools of allocated (but unused) memory available for future use. If memory is a premium on your system and you believe your malloc library outperforms Squid routines, disable this. DOC_END NAME: memory_pools_limit COMMENT: (bytes) TYPE: b_int64_t DEFAULT: 5 MB LOC: Config.MemPools.limit DOC_START Used only with memory_pools on: memory_pools_limit 50 MB If set to a non-zero value, Squid will keep at most the specified limit of allocated (but unused) memory in memory pools. All free() requests that exceed this limit will be handled by your malloc library. Squid does not pre-allocate any memory, just safe-keeps objects that otherwise would be free()d. Thus, it is safe to set memory_pools_limit to a reasonably high value even if your configuration will use less memory. If set to none, Squid will keep all memory it can. That is, there will be no limit on the total amount of memory used for safe-keeping. To disable memory allocation optimization, do not set memory_pools_limit to 0 or none. Set memory_pools to "off" instead. An overhead for maintaining memory pools is not taken into account when the limit is checked. This overhead is close to four bytes per object kept. However, pools may actually _save_ memory because of reduced memory thrashing in your malloc library. DOC_END NAME: forwarded_for COMMENT: on|off|transparent|truncate|delete TYPE: string DEFAULT: on LOC: opt_forwarded_for DOC_START If set to "on", Squid will append your client's IP address in the HTTP requests it forwards. By default it looks like: X-Forwarded-For: 192.1.2.3 If set to "off", it will appear as X-Forwarded-For: unknown If set to "transparent", Squid will not alter the X-Forwarded-For header in any way. If set to "delete", Squid will delete the entire X-Forwarded-For header. If set to "truncate", Squid will remove all existing X-Forwarded-For entries, and place the client IP as the sole entry. DOC_END NAME: cachemgr_passwd TYPE: cachemgrpasswd DEFAULT: none DEFAULT_DOC: No password. Actions which require password are denied. LOC: Config.passwd_list DOC_START Specify passwords for cachemgr operations. Usage: cachemgr_passwd password action action ... Some valid actions are (see cache manager menu for a full list): 5min 60min asndb authenticator cbdata client_list comm_incoming config * counters delay digest_stats dns events filedescriptors fqdncache histograms http_headers info io ipcache mem menu netdb non_peers objects offline_toggle * pconn peer_select reconfigure * redirector refresh server_list shutdown * store_digest storedir utilization via_headers vm_objects * Indicates actions which will not be performed without a valid password, others can be performed if not listed here. To disable an action, set the password to "disable". To allow performing an action without a password, set the password to "none". Use the keyword "all" to set the same password for all actions. Example: cachemgr_passwd secret shutdown cachemgr_passwd lesssssssecret info stats/objects cachemgr_passwd disable all DOC_END NAME: client_db COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.client_db DOC_START If you want to disable collecting per-client statistics, turn off client_db here. DOC_END NAME: refresh_all_ims COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.refresh_all_ims DOC_START When you enable this option, squid will always check the origin server for an update when a client sends an If-Modified-Since request. Many browsers use IMS requests when the user requests a reload, and this ensures those clients receive the latest version. By default (off), squid may return a Not Modified response based on the age of the cached version. DOC_END NAME: reload_into_ims IFDEF: USE_HTTP_VIOLATIONS COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.reload_into_ims DOC_START When you enable this option, client no-cache or ``reload'' requests will be changed to If-Modified-Since requests. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. see also refresh_pattern for a more selective approach. DOC_END NAME: connect_retries TYPE: int LOC: Config.connect_retries DEFAULT: 0 DEFAULT_DOC: Do not retry failed connections. DOC_START Limits the number of reopening attempts when establishing a single TCP connection. All these attempts must still complete before the applicable connection opening timeout expires. By default and when connect_retries is set to zero, Squid does not retry failed connection opening attempts. The (not recommended) maximum is 10 tries. An attempt to configure a higher value results in the value of 10 being used (with a warning). Squid may open connections to retry various high-level forwarding failures. For an outside observer, that activity may look like a low-level connection reopening attempt, but those high-level retries are governed by forward_max_tries instead. See also: connect_timeout, forward_timeout, icap_connect_timeout, ident_timeout, and forward_max_tries. DOC_END NAME: retry_on_error TYPE: onoff LOC: Config.retry.onerror DEFAULT: off DOC_START If set to ON Squid will automatically retry requests when receiving an error response with status 403 (Forbidden), 500 (Internal Error), 501 or 503 (Service not available). Status 502 and 504 (Gateway errors) are always retried. This is mainly useful if you are in a complex cache hierarchy to work around access control errors. NOTE: This retry will attempt to find another working destination. Which is different from the server which just failed. DOC_END NAME: as_whois_server TYPE: string LOC: Config.as_whois_server DEFAULT: whois.ra.net DOC_START WHOIS server to query for AS numbers. NOTE: AS numbers are queried only when Squid starts up, not for every request. DOC_END NAME: offline_mode TYPE: onoff LOC: Config.onoff.offline DEFAULT: off DOC_START Enable this option and Squid will never try to validate cached objects. DOC_END NAME: uri_whitespace TYPE: uri_whitespace LOC: Config.uri_whitespace DEFAULT: strip DOC_START What to do with requests that have whitespace characters in the URI. Options: strip: The whitespace characters are stripped out of the URL. This is the behavior recommended by RFC2396 and RFC3986 for tolerant handling of generic URI. NOTE: This is one difference between generic URI and HTTP URLs. deny: The request is denied. The user receives an "Invalid Request" message. This is the behaviour recommended by RFC2616 for safe handling of HTTP request URL. allow: The request is allowed and the URI is not changed. The whitespace characters remain in the URI. Note the whitespace is passed to redirector processes if they are in use. Note this may be considered a violation of RFC2616 request parsing where whitespace is prohibited in the URL field. encode: The request is allowed and the whitespace characters are encoded according to RFC1738. chop: The request is allowed and the URI is chopped at the first whitespace. NOTE the current Squid implementation of encode and chop violates RFC2616 by not using a 301 redirect after altering the URL. DOC_END NAME: chroot TYPE: string LOC: Config.chroot_dir DEFAULT: none DOC_START Specifies a directory where Squid should do a chroot() while initializing. This also causes Squid to fully drop root privileges after initializing. This means, for example, if you use a HTTP port less than 1024 and try to reconfigure, you may get an error saying that Squid can not open the port. DOC_END NAME: pipeline_prefetch TYPE: pipelinePrefetch LOC: Config.pipeline_max_prefetch DEFAULT: 0 DEFAULT_DOC: Do not pre-parse pipelined requests. DOC_START HTTP clients may send a pipeline of 1+N requests to Squid using a single connection, without waiting for Squid to respond to the first of those requests. This option limits the number of concurrent requests Squid will try to handle in parallel. If set to N, Squid will try to receive and process up to 1+N requests on the same connection concurrently. Defaults to 0 (off) for bandwidth management and access logging reasons. NOTE: pipelining requires persistent connections to clients. WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication. DOC_END NAME: high_response_time_warning TYPE: int COMMENT: (msec) LOC: Config.warnings.high_rptm DEFAULT: 0 DEFAULT_DOC: disabled. DOC_START If the one-minute median response time exceeds this value, Squid prints a WARNING with debug level 0 to get the administrators attention. The value is in milliseconds. DOC_END NAME: high_page_fault_warning TYPE: int LOC: Config.warnings.high_pf DEFAULT: 0 DEFAULT_DOC: disabled. DOC_START If the one-minute average page fault rate exceeds this value, Squid prints a WARNING with debug level 0 to get the administrators attention. The value is in page faults per second. DOC_END NAME: high_memory_warning TYPE: b_size_t LOC: Config.warnings.high_memory IFDEF: HAVE_MSTATS&&HAVE_GNUMALLOC_H DEFAULT: 0 KB DEFAULT_DOC: disabled. DOC_START If the memory usage (as determined by gnumalloc, if available and used) exceeds this amount, Squid prints a WARNING with debug level 0 to get the administrators attention. DOC_END # TODO: link high_memory_warning to mempools? NAME: sleep_after_fork COMMENT: (microseconds) TYPE: int LOC: Config.sleep_after_fork DEFAULT: 0 DOC_START When this is set to a non-zero value, the main Squid process sleeps the specified number of microseconds after a fork() system call. This sleep may help the situation where your system reports fork() failures due to lack of (virtual) memory. Note, however, if you have a lot of child processes, these sleep delays will add up and your Squid will not service requests for some amount of time until all the child processes have been started. On Windows value less then 1000 (1 milliseconds) are rounded to 1000. DOC_END NAME: windows_ipaddrchangemonitor IFDEF: _SQUID_WINDOWS_ COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.WIN32_IpAddrChangeMonitor DOC_START On Windows Squid by default will monitor IP address changes and will reconfigure itself after any detected event. This is very useful for proxies connected to internet with dial-up interfaces. In some cases (a Proxy server acting as VPN gateway is one) it could be desiderable to disable this behaviour setting this to 'off'. Note: after changing this, Squid service must be restarted. DOC_END NAME: eui_lookup TYPE: onoff IFDEF: USE_SQUID_EUI DEFAULT: on LOC: Eui::TheConfig.euiLookup DOC_START Whether to lookup the EUI or MAC address of a connected client. DOC_END NAME: max_filedescriptors max_filedesc TYPE: int DEFAULT: 0 DEFAULT_DOC: Use operating system soft limit set by ulimit. LOC: Config.max_filedescriptors DOC_START Set the maximum number of filedescriptors, either below the operating system default or up to the hard limit. Remove from squid.conf to inherit the current ulimit soft limit setting. Note: Changing this requires a restart of Squid. Also not all I/O types supports large values (eg on Windows). DOC_END NAME: force_request_body_continuation TYPE: acl_access LOC: Config.accessList.forceRequestBodyContinuation DEFAULT: none DEFAULT_DOC: Deny, unless rules exist in squid.conf. DOC_START This option controls how Squid handles data upload requests from HTTP and FTP agents that require a "Please Continue" control message response to actually send the request body to Squid. It is mostly useful in adaptation environments. When Squid receives an HTTP request with an "Expect: 100-continue" header or an FTP upload command (e.g., STOR), Squid normally sends the request headers or FTP command information to an adaptation service (or peer) and waits for a response. Most adaptation services (and some broken peers) may not respond to Squid at that stage because they may decide to wait for the HTTP request body or FTP data transfer. However, that request body or data transfer may never come because Squid has not responded with the HTTP 100 or FTP 150 (Please Continue) control message to the request sender yet! An allow match tells Squid to respond with the HTTP 100 or FTP 150 (Please Continue) control message on its own, before forwarding the request to an adaptation service or peer. Such a response usually forces the request sender to proceed with sending the body. A deny match tells Squid to delay that control response until the origin server confirms that the request body is needed. Delaying is the default behavior. DOC_END NAME: http_upgrade_request_protocols TYPE: http_upgrade_request_protocols LOC: Config.http_upgrade_request_protocols DEFAULT: none DEFAULT_DOC: Upgrade header dropped, effectively blocking an upgrade attempt. DOC_START Controls client-initiated and server-confirmed switching from HTTP to another protocol (or to several protocols) using HTTP Upgrade mechanism defined in RFC 7230 Section 6.7. Squid itself does not understand the protocols being upgraded to and participates in the upgraded communication only as a dumb TCP proxy. Admins should not allow upgrading to protocols that require a more meaningful proxy participation. Usage: http_upgrade_request_protocols allow|deny [!]acl ... The required "protocol" parameter is either an all-caps word OTHER or an explicit protocol name (e.g. "WebSocket") optionally followed by a slash and a version token (e.g. "HTTP/3"). Explicit protocol names and versions are case sensitive. When an HTTP client sends an Upgrade request header, Squid iterates over the client-offered protocols and, for each protocol P (with an optional version V), evaluates the first non-empty set of http_upgrade_request_protocols rules (if any) from the following list: * All rules with an explicit protocol name equal to P. * All rules that use OTHER instead of a protocol name. In other words, rules using OTHER are considered for protocol P if and only if there are no rules mentioning P by name. If both of the above sets are empty, then Squid removes protocol P from the Upgrade offer. If the client sent a versioned protocol offer P/X, then explicit rules referring to the same-name but different-version protocol P/Y are declared inapplicable. Inapplicable rules are not evaluated (i.e. are ignored). However, inapplicable rules still belong to the first set of rules for P. Within the applicable rule subset, individual rules are evaluated in their configuration order. If all ACLs of an applicable "allow" rule match, then the protocol offered by the client is forwarded to the next hop as is. If all ACLs of an applicable "deny" rule match, then the offer is dropped. If no applicable rules have matching ACLs, then the offer is also dropped. The first matching rule also ends rules evaluation for the offered protocol. If all client-offered protocols are removed, then Squid forwards the client request without the Upgrade header. Squid never sends an empty Upgrade request header. An Upgrade request header with a value violating HTTP syntax is dropped and ignored without an attempt to use extractable individual protocol offers. Upon receiving an HTTP 101 (Switching Protocols) control message, Squid checks that the server listed at least one protocol name and sent a Connection:upgrade response header. Squid does not understand individual protocol naming and versioning concepts enough to implement stricter checks, but an admin can restrict HTTP 101 (Switching Protocols) responses further using http_reply_access. Responses denied by http_reply_access rules and responses flagged by the internal Upgrade checks result in HTTP 502 (Bad Gateway) ERR_INVALID_RESP errors and Squid-to-server connection closures. If Squid sends an Upgrade request header, and the next hop (e.g., the origin server) responds with an acceptable HTTP 101 (Switching Protocols), then Squid forwards that message to the client and becomes a TCP tunnel. The presence of an Upgrade request header alone does not preclude cache lookups. In other words, an Upgrade request might be satisfied from the cache, using regular HTTP caching rules. This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Each of the following groups of configuration lines represents a separate configuration example: # never upgrade to protocol Foo; all others are OK http_upgrade_request_protocols Foo deny all http_upgrade_request_protocols OTHER allow all # only allow upgrades to protocol Bar (except for its first version) http_upgrade_request_protocols Bar/1 deny all http_upgrade_request_protocols Bar allow all http_upgrade_request_protocols OTHER deny all # this rule is optional # only allow upgrades to protocol Baz, and only if Baz is the only offer acl UpgradeHeaderHasMultipleOffers ... http_upgrade_request_protocols Baz deny UpgradeHeaderHasMultipleOffers http_upgrade_request_protocols Baz allow all DOC_END NAME: server_pconn_for_nonretriable TYPE: acl_access DEFAULT: none DEFAULT_DOC: Open new connections for forwarding requests Squid cannot retry safely. LOC: Config.accessList.serverPconnForNonretriable DOC_START This option provides fine-grained control over persistent connection reuse when forwarding HTTP requests that Squid cannot retry. It is useful in environments where opening new connections is very expensive (e.g., all connections are secured with TLS with complex client and server certificate validation) and race conditions associated with persistent connections are very rare and/or only cause minor problems. HTTP prohibits retrying unsafe and non-idempotent requests (e.g., POST). Squid limitations also prohibit retrying all requests with bodies (e.g., PUT). By default, when forwarding such "risky" requests, Squid opens a new connection to the server or cache_peer, even if there is an idle persistent connection available. When Squid is configured to risk sending a non-retriable request on a previously used persistent connection, and the server closes the connection before seeing that risky request, the user gets an error response from Squid. In most cases, that error response will be HTTP 502 (Bad Gateway) with ERR_ZERO_SIZE_OBJECT or ERR_WRITE_ERROR (peer connection reset) error detail. If an allow rule matches, Squid reuses an available idle persistent connection (if any) for the request that Squid cannot retry. If a deny rule matches, then Squid opens a new connection for the request that Squid cannot retry. This option does not affect requests that Squid can retry. They will reuse idle persistent connections (if any). This clause only supports fast acl types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. Example: acl SpeedIsWorthTheRisk method POST server_pconn_for_nonretriable allow SpeedIsWorthTheRisk DOC_END NAME: happy_eyeballs_connect_timeout COMMENT: (msec) TYPE: int DEFAULT: 250 LOC: Config.happyEyeballs.connect_timeout DOC_START This Happy Eyeballs (RFC 8305) tuning directive specifies the minimum delay between opening a primary to-server connection and opening a spare to-server connection for the same master transaction. This delay is similar to the Connection Attempt Delay in RFC 8305, but it is only applied to the first spare connection attempt. Subsequent spare connection attempts use happy_eyeballs_connect_gap, and primary connection attempts are not artificially delayed at all. Terminology: The "primary" and "spare" designations are determined by the order of DNS answers received by Squid: If Squid DNS AAAA query was answered first, then primary connections are connections to IPv6 peer addresses (while spare connections use IPv4 addresses). Similarly, if Squid DNS A query was answered first, then primary connections are connections to IPv4 peer addresses (while spare connections use IPv6 addresses). Shorter happy_eyeballs_connect_timeout values reduce master transaction response time, potentially improving user-perceived response times (i.e., making user eyeballs happier). Longer delays reduce both concurrent connection level and server bombardment with connection requests, potentially improving overall Squid performance and reducing the chance of being blocked by servers for opening too many unused connections. RFC 8305 prohibits happy_eyeballs_connect_timeout values smaller than 10 (milliseconds) to "avoid congestion collapse in the presence of high packet-loss rates". The following Happy Eyeballs directives place additional connection opening restrictions: happy_eyeballs_connect_gap and happy_eyeballs_connect_limit. DOC_END NAME: happy_eyeballs_connect_gap COMMENT: (msec) TYPE: int DEFAULT: -1 DEFAULT_DOC: no artificial delays between spare attempts LOC: Config.happyEyeballs.connect_gap DOC_START This Happy Eyeballs (RFC 8305) tuning directive specifies the minimum delay between opening spare to-server connections (to any server; i.e. across all concurrent master transactions in a Squid instance). Each SMP worker currently multiplies the configured gap by the total number of workers so that the combined spare connection opening rate of a Squid instance obeys the configured limit. The workers do not coordinate connection openings yet; a micro burst of spare connection openings may violate the configured gap. This directive has similar trade-offs as happy_eyeballs_connect_timeout, but its focus is on limiting traffic amplification effects for Squid as a whole, while happy_eyeballs_connect_timeout works on an individual master transaction level. The following Happy Eyeballs directives place additional connection opening restrictions: happy_eyeballs_connect_timeout and happy_eyeballs_connect_limit. See the former for related terminology. DOC_END NAME: happy_eyeballs_connect_limit TYPE: int DEFAULT: -1 DEFAULT_DOC: no artificial limit on the number of concurrent spare attempts LOC: Config.happyEyeballs.connect_limit DOC_START This Happy Eyeballs (RFC 8305) tuning directive specifies the maximum number of spare to-server connections (to any server; i.e. across all concurrent master transactions in a Squid instance). Each SMP worker gets an equal share of the total limit. However, the workers do not share the actual connection counts yet, so one (busier) worker cannot "borrow" spare connection slots from another (less loaded) worker. Setting this limit to zero disables concurrent use of primary and spare TCP connections: Spare connection attempts are made only after all primary attempts fail. However, Squid would still use the DNS-related optimizations of the Happy Eyeballs approach. This directive has similar trade-offs as happy_eyeballs_connect_gap, but its focus is on limiting Squid overheads, while happy_eyeballs_connect_gap focuses on the origin server and peer overheads. The following Happy Eyeballs directives place additional connection opening restrictions: happy_eyeballs_connect_timeout and happy_eyeballs_connect_gap. See the former for related terminology. DOC_END EOF .