# # $Id: cf.data.pre,v 1.382.2.35 2010/02/12 20:55:04 hno Exp $ # # SQUID Web Proxy Cache http://www.squid-cache.org/ # ---------------------------------------------------------- # # Squid is the result of efforts by numerous individuals from # the Internet community; see the CONTRIBUTORS file for full # details. Many organizations have provided support for Squid's # development; see the SPONSORS file for full details. Squid is # Copyrighted (C) 2000 by the Regents of the University of # California; see the COPYRIGHT file for full details. Squid # incorporates software developed and/or copyrighted by other # sources; see the CREDITS file for full details. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. # COMMENT_START WELCOME TO SQUID @VERSION@ ---------------------------- This is the default Squid configuration file. You may wish to look at the Squid home page (http://www.squid-cache.org/) for the FAQ and other documentation. The default Squid config file shows what the defaults for various options happen to be. If you don't need to change the default, you shouldn't uncomment the line. Doing so may cause run-time problems. In some cases "none" refers to no default setting at all, while in other cases it refers to a valid option - the comments for that keyword indicate if this is the case. COMMENT_END COMMENT_START OPTIONS FOR AUTHENTICATION ----------------------------------------------------------------------------- COMMENT_END NAME: auth_param TYPE: authparam LOC: Config.authConfig DEFAULT: none DOC_START This is used to define parameters for the various authentication schemes supported by Squid. format: auth_param scheme parameter [setting] The order in which authentication schemes are presented to the client is dependent on the order the scheme first appears in config file. IE has a bug (it's not RFC 2617 compliant) in that it will use the basic scheme if basic is the first entry presented, even if more secure schemes are presented. For now use the order in the recommended settings section below. If other browsers have difficulties (don't recognize the schemes offered even if you are using basic) either put basic first, or disable the other schemes (by commenting out their program entry). Once an authentication scheme is fully configured, it can only be shutdown by shutting squid down and restarting. Changes can be made on the fly and activated with a reconfigure. I.E. You can change to a different helper, but not unconfigure the helper completely. Please note that while this directive defines how Squid processes authentication it does not automatically activate authentication. To use authentication you must in addition make use of ACLs based on login name in http_access (proxy_auth, proxy_auth_regex or external with %LOGIN used in the format tag). The browser will be challenged for authentication on the first such acl encountered in http_access processing and will also be re-challenged for new login credentials if the request is being denied by a proxy_auth type acl. WARNING: authentication can't be used in a transparently intercepting proxy as the client then thinks it is talking to an origin server and not the proxy. This is a limitation of bending the TCP/IP protocol to transparently intercepting port 80, not a limitation in Squid. === Parameters for the basic scheme follow. === "program" cmdline Specify the command for the external authenticator. Such a program reads a line containing "username password" and replies "OK" or "ERR" in an endless loop. "ERR" responses may optionally be followed by a error description available as %m in the returned error page. By default, the basic authentication scheme is not used unless a program is specified. If you want to use the traditional proxy authentication, jump over to the helpers/basic_auth/NCSA directory and type: % make % make install Then, set this line to something like auth_param basic program @DEFAULT_PREFIX@/libexec/ncsa_auth @DEFAULT_PREFIX@/etc/passwd "children" numberofchildren The number of authenticator processes to spawn. If you start too few squid will have to wait for them to process a backlog of credential verifications, slowing it down. When credential verifications are done via a (slow) network you are likely to need lots of authenticator processes. auth_param basic children 5 "concurrency" numberofconcurrentrequests The number of concurrent requests/channels the helper supports. Changes the protocol used to include a channel number first on the request/response line, allowing multiple requests to be sent to the same helper in parallell without wating for the response. Must not be set unless it's known the helper supports this. "realm" realmstring Specifies the realm name which is to be reported to the client for the basic proxy authentication scheme (part of the text the user will see when prompted their username and password). auth_param basic realm Squid proxy-caching web server "credentialsttl" timetolive Specifies how long squid assumes an externally validated username:password pair is valid for - in other words how often the helper program is called for that user. Set this low to force revalidation with short lived passwords. Note that setting this high does not impact your susceptibility to replay attacks unless you are using an one-time password system (such as SecureID). If you are using such a system, you will be vulnerable to replay attacks unless you also use the max_user_ip ACL in an http_access rule. auth_param basic credentialsttl 2 hours "casesensitive" on|off Specifies if usernames are case sensitive. Most user databases are case insensitive allowing the same username to be spelled using both lower and upper case letters, but some are case sensitive. This makes a big difference for user_max_ip ACL processing and similar. auth_param basic casesensitive off "blankpassword" on|off Specifies if blank passwords should be supported. Defaults to off as there is multiple authentication backends which handles blank passwords as "guest" access. === Parameters for the digest scheme follow === "program" cmdline Specify the command for the external authenticator. Such a program reads a line containing "username":"realm" and replies with the appropriate H(A1) value hex encoded or ERR if the user (or his H(A1) hash) does not exists. See RFC 2616 for the definition of H(A1). "ERR" responses may optionally be followed by a error description available as %m in the returned error page. By default, the digest authentication scheme is not used unless a program is specified. If you want to use a digest authenticator, jump over to the helpers/digest_auth/ directory and choose the authenticator to use. It it's directory type % make % make install Then, set this line to something like auth_param digest program @DEFAULT_PREFIX@/libexec/digest_auth_pw @DEFAULT_PREFIX@/etc/digpass "children" numberofchildren The number of authenticator processes to spawn. If you start too few squid will have to wait for them to process a backlog of credential verifications, slowing it down. When credential verifications are done via a (slow) network you are likely to need lots of authenticator processes. auth_param digest children 5 "concurrency" numberofconcurrentrequests The number of concurrent requests/channels the helper supports. Changes the protocol used to include a channel number first on the request/response line, allowing multiple requests to be sent to the same helper in parallell without wating for the response. Must not be set unless it's known the helper supports this. "realm" realmstring Specifies the realm name which is to be reported to the client for the digest proxy authentication scheme (part of the text the user will see when prompted their username and password). auth_param digest realm Squid proxy-caching web server "nonce_garbage_interval" timeinterval Specifies the interval that nonces that have been issued to clients are checked for validity. auth_param digest nonce_garbage_interval 5 minutes "nonce_max_duration" timeinterval Specifies the maximum length of time a given nonce will be valid for. auth_param digest nonce_max_duration 30 minutes "nonce_max_count" number Specifies the maximum number of times a given nonce can be used. auth_param digest nonce_max_count 50 "nonce_strictness" on|off Determines if squid requires strict increment-by-1 behavior for nonce counts, or just incrementing (off - for use when useragents generate nonce counts that occasionally miss 1 (ie, 1,2,4,6)). auth_param digest nonce_strictness off "check_nonce_count" on|off This directive if set to off can disable the nonce count check completely to work around buggy digest qop implementations in certain mainstream browser versions. Default on to check the nonce count to protect from authentication replay attacks. auth_param digest check_nonce_count on "post_workaround" on|off This is a workaround to certain buggy browsers who sends an incorrect request digest in POST requests when reusing the same nonce as acquired earlier in response to a GET request. auth_param digest post_workaround off === NTLM scheme options follow === "program" cmdline Specify the command for the external NTLM authenticator. Such a program participates in the NTLMSSP exchanges between Squid and the client and reads commands according to the Squid NTLMSSP helper protocol. See helpers/ntlm_auth/ for details. Recommended ntlm authenticator is ntlm_auth from Samba-3.X, but a number of other ntlm authenticators is available. By default, the ntlm authentication scheme is not used unless a program is specified. auth_param ntlm program /path/to/samba/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp "children" numberofchildren The number of authenticator processes to spawn. If you start too few squid will have to wait for them to process a backlog of credential verifications, slowing it down. When credential verifications are done via a (slow) network you are likely to need lots of authenticator processes. auth_param ntlm children 5 "keep_alive" on|off This option enables the use of keep-alive on the initial authentication request. It has been reported some versions of MSIE have problems if this is enabled, but performance will be increased if enabled. auth_param ntlm keep_alive on === Negotiate scheme options follow === "program" cmdline Specify the command for the external Negotiate authenticator. Such a program participates in the SPNEGO exchanges between Squid and the client and reads commands according to the Squid ntlmssp helper protocol. See helpers/ntlm_auth/ for details. Recommended SPNEGO authenticator is ntlm_auth from Samba-4.X. By default, the Negotiate authentication scheme is not used unless a program is specified. auth_param negotiate program /path/to/samba/bin/ntlm_auth --helper-protocol=gss-spnego "children" numberofchildren The number of authenticator processes to spawn. If you start too few squid will have to wait for them to process a backlog of credential verifications, slowing it down. When credential verifications are done via a (slow) network you are likely to need lots of authenticator processes. auth_param negotiate children 5 "keep_alive" on|off If you experience problems with PUT/POST requests when using the Negotiate authentication scheme then you can try setting this to off. This will cause Squid to forcibly close the connection on the initial requests where the browser asks which schemes are supported by the proxy. auth_param negotiate keep_alive on NOCOMMENT_START #Recommended minimum configuration per scheme: #auth_param negotiate program #auth_param negotiate children 5 #auth_param negotiate keep_alive on #auth_param ntlm program #auth_param ntlm children 5 #auth_param ntlm keep_alive on #auth_param digest program #auth_param digest children 5 #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 basic program #auth_param basic children 5 #auth_param basic realm Squid proxy-caching web server #auth_param basic credentialsttl 2 hours #auth_param basic casesensitive off NOCOMMENT_END DOC_END NAME: authenticate_cache_garbage_interval TYPE: time_t DEFAULT: 1 hour LOC: Config.authenticateGCInterval DOC_START The time period between garbage collection across the username cache. This is a tradeoff 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 TYPE: time_t DEFAULT: 1 hour LOC: Config.authenticateTTL 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 TYPE: time_t LOC: Config.authenticateIpTTL DEFAULT: 0 seconds 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 dialups. 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) children=n number of processes spawn to service external acl lookups of this type. (default 5). concurrency=n concurrency level per process. Only used with helpers capable of processing more than one query at a time. Note: see compatibility note below cache=n result cache size, 0 is unbounded (default) grace= Percentage remaining of TTL where a refresh of a cached entry should be initiated without needing to wait for a new reply. (default 0 for no grace period) protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers FORMAT specifications %LOGIN Authenticated user login name %EXT_USER Username from external acl %IDENT Ident user name %SRC Client IP %SRCPORT Client source port %DST Requested host %PROTO Requested protocol %PORT Requested port %METHOD Request method %MYADDR Squid interface address %MYPORT Squid http_port number %PATH Requested URL-path (including query-string if any) %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_xx SSL User certificate issuer attribute xx %{Header} HTTP request header "Header" %{Hdr:member} HTTP request header "Hdr" list member "member" %{Hdr:;member} HTTP request header list member using ; as list separator. ; can be any non-alphanumeric character. %ACL The ACL name %DATA The ACL arguments. If not used then any arguments is automatically added at the end In addition to the above, any string specified in the referencing acl will also be included in the helper request line, after the specified formats (see the "acl external" directive) The helper receives lines per the above format specification, and returns lines starting with OK or ERR indicating the validity of the request and optionally followed by additional keywords with more details. General result syntax: OK/ERR keyword=value ... Defined keywords: user= The users name (login also understood) password= The users password (for PROXYPASS login= cache_peer) message= Error message or similar used as %o in error messages (error also understood) log= String to be logged in access.log. Available as %ea in logformat specifications If protocol=3.0 (the default) then URL escaping is used to protect each value in both requests and responses. If using protocol=2.5 then all values need to be enclosed in quotes if they may contain whitespace, or the whitespace escaped using \. And quotes or \ characters within the keyword value must be \ escaped. When using the concurrency= option the protocol is changed by introducing a query channel tag infront of the request/response. The query channel tag is a number between 0 and concurrency-1. Compatibility Note: The children= option was named concurrency= in Squid-2.5.STABLE3 and earlier, and was accepted as an alias for the duration of the Squid-2.5 releases to keep compatibility. However, the meaning of concurrency= option has changed in Squid-2.6 to match that of Squid-3 and the old syntax no longer works. DOC_END NAME: acl TYPE: acl LOC: Config.aclList DEFAULT: none DOC_START Defining an Access List acl aclname acltype string1 ... acl aclname acltype "file" ... when using "file", the file should contain one item per line acltype is one of the types described below By default, regular expressions are CASE-SENSITIVE. To make them case-insensitive, use the -i option. acl aclname src ip-address/netmask ... (clients IP address) acl aclname src addr1-addr2/netmask ... (range of addresses) acl aclname dst ip-address/netmask ... (URL host's IP address) acl aclname myip ip-address/netmask ... (local socket IP address) acl aclname arp mac-address ... (xx:xx:xx:xx:xx:xx notation) # The arp ACL requires the special configure option --enable-arp-acl. # Furthermore, the arp ACL code is not portable to all operating systems. # It works on Linux, Solaris, FreeBSD and some other *BSD variants. # # NOTE: Squid can only determine the MAC address for clients that are on # the same subnet. If the client is on a different subnet, then Squid cannot # find out its MAC address. acl aclname srcdomain .foo.com ... # reverse lookup, client IP acl aclname dstdomain .foo.com ... # Destination server from URL acl aclname srcdom_regex [-i] xxx ... # regex matching client name acl aclname dstdom_regex [-i] xxx ... # regex matching server # 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 time [day-abbrevs] [h1:m1-h2:m2] 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 acl aclname urlpath_regex [-i] \.gif$ ... # regex matching on URL path acl aclname urllogin [-i] [^a-zA-Z0-9] ... # regex matching on URL login field acl aclname port 80 70 21 ... acl aclname port 0-1024 ... # ranges allowed acl aclname myport 3128 ... # (local socket TCP port) acl aclname proto HTTP FTP ... acl aclname method GET POST ... acl aclname browser [-i] regexp ... # pattern match on User-Agent header (see also req_header below) acl aclname referer_regex [-i] regexp ... # pattern match on Referer header # Referer is highly unreliable, so use with care acl aclname ident username ... acl aclname ident_regex [-i] pattern ... # string match on ident output. # use REQUIRED to accept any non-null ident. acl aclname src_as number ... acl aclname dst_as number ... # 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 proxy_auth [-i] username ... acl aclname proxy_auth_regex [-i] pattern ... # list of valid usernames # use REQUIRED to accept any valid username. # # 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 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 # Example: # # acl snmppublic snmp_community public acl aclname maxconn number # This will be matched when the client's IP address has # more than HTTP connections established. 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. # 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 req_mime_type mime-type1 ... # 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. # 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" # ACLs. acl aclname rep_mime_type mime-type1 ... # 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. # 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. # # Example: # # acl many_spaces rep_header Content-Disposition -i [[:space:]]{3,} acl acl_name external class_name [arguments...] # external ACL lookup via a helper class defined by the # external_acl_type directive. acl urlgroup group1 ... # match against the urlgroup as indicated by redirectors acl aclname user_cert attribute values... # match against attributes in a user SSL certificate # attribute is one of DN/C/O/CN/L/ST 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 acl aclname ext_user username ... acl aclname ext_user_regex [-i] pattern ... # string match on username returned by external acl helper # use REQUIRED to accept any non-null user name. 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: acl all src 0.0.0.0/0.0.0.0 acl manager proto cache_object acl localhost src 127.0.0.1/255.255.255.255 acl to_localhost dst 127.0.0.0/8 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 acl CONNECT method CONNECT NOCOMMENT_END DOC_END NAME: http_access TYPE: acl_access LOC: Config.accessList.http DEFAULT: none DEFAULT_IF_NONE: deny all DOC_START Allowing or Denying access based on defined access lists Access to the HTTP 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" or "allow all" entry at the end of your access lists to avoid potential confusion. NOCOMMENT_START #Recommended minimum configuration: # # Only allow cachemgr access from localhost http_access allow manager localhost http_access deny manager # Deny requests to unknown ports http_access deny !Safe_ports # Deny CONNECT to other than SSL ports http_access deny CONNECT !SSL_ports # # We strongly recommend the following be uncommented to protect innocent # web applications running on the proxy server who think the only # one who can access services on "localhost" is a local user #http_access deny to_localhost # # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # Example rule allowing access from your local networks. Adapt # to list your (internal) IP networks from where browsing should # be allowed #acl our_networks src 192.168.1.0/24 192.168.2.0/24 #http_access allow our_networks # And finally deny all other access to this proxy http_access deny all NOCOMMENT_END DOC_END NAME: http_access2 TYPE: acl_access LOC: Config.accessList.http2 DEFAULT: none DOC_START Allowing or Denying access based on defined access lists Identical to http_access, but runs after redirectors. 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_IF_NONE: allow all 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. DOC_END NAME: icp_access TYPE: acl_access LOC: Config.accessList.icp DEFAULT: none DEFAULT_IF_NONE: deny all DOC_START Allowing or Denying access to the ICP port based on defined access lists icp_access allow|deny [!]aclname ... See http_access for details NOCOMMENT_START #Allow ICP queries from everyone icp_access allow all NOCOMMENT_END DOC_END NAME: htcp_access IFDEF: USE_HTCP TYPE: acl_access LOC: Config.accessList.htcp DEFAULT: none DEFAULT_IF_NONE: deny all DOC_START Allowing or Denying access to the HTCP port based on defined access lists htcp_access allow|deny [!]aclname ... See http_access for details 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 or htcp-oldsquid options. #Allow HTCP queries from everyone htcp_access allow all DOC_END NAME: htcp_clr_access IFDEF: USE_HTCP TYPE: acl_access LOC: Config.accessList.htcp_clr DEFAULT: none DEFAULT_IF_NONE: deny all DOC_START Allowing or Denying access to purge content using HTCP based on defined access lists htcp_clr_access allow|deny [!]aclname ... See http_access for details #Allow HTCP CLR requests from trusted peers acl htcp_clr_peer src 172.16.1.2 htcp_clr_access allow htcp_clr_peer DOC_END NAME: miss_access TYPE: acl_access LOC: Config.accessList.miss DEFAULT: none DOC_START Use to force your neighbors to use you as a sibling instead of a parent. For example: acl localclients src 172.16.0.0/16 miss_access allow localclients miss_access deny !localclients This means only your local clients are allowed to fetch MISSES and all other clients can only fetch HITS. By default, allow all clients who passed the http_access rules to fetch MISSES from us. NOCOMMENT_START #Default setting: # miss_access allow all NOCOMMENT_END DOC_END NAME: ident_lookup_access TYPE: acl_access IFDEF: USE_IDENT DEFAULT: none DEFAULT_IF_NONE: deny all LOC: Config.accessList.identLookup DOC_START A list of ACL elements which, if matched, cause an ident (RFC931) 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 198.168.1.0/255.255.255.0 ident_lookup_access allow ident_aware_hosts ident_lookup_access deny all Only src type ACL checks are fully supported. A src_domain ACL might work at times, but it will not always provide the correct result. DOC_END NAME: reply_body_max_size COMMENT: bytes deny acl acl... TYPE: body_size_t DEFAULT: none DEFAULT_IF_NONE: 0 allow all LOC: Config.ReplyBodySize DOC_START This option specifies the maximum size of a reply body in bytes. 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 with a result of "deny" 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. If you set this parameter to zero (the default), there will be no limit imposed. DOC_END COMMENT_START OPTIONS FOR X-Forwarded-For ----------------------------------------------------------------------------- COMMENT_END NAME: follow_x_forwarded_for TYPE: acl_access IFDEF: FOLLOW_X_FORWARDED_FOR LOC: Config.accessList.followXFF DEFAULT: none DEFAULT_IF_NONE: deny all DOC_START Allowing or Denying the X-Forwarded-For header to be followed to find the original source of a request. Requests may pass through a chain of several other proxies before reaching us. The X-Forwarded-For header will contain a comma-separated list of the IP addresses in the chain, with the rightmost address being the most recent. If a request reaches us from a source that is allowed by this configuration item, then we consult the X-Forwarded-For header to see where that host received the request from. If the X-Forwarded-For header contains multiple addresses, and if acl_uses_indirect_client is on, then we continue backtracking until we reach an address for which we are not allowed to follow the X-Forwarded-For header, or until we reach the first address in the list. (If acl_uses_indirect_client is off, then it's impossible to backtrack through more than one level of X-Forwarded-For addresses.) 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, delay pools and logging, depending on the acl_uses_indirect_client, delay_pool_uses_indirect_client and log_uses_indirect_client options. SECURITY CONSIDERATIONS: Any host for which we follow the X-Forwarded-For header can place incorrect information in the 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. DOC_END NAME: delay_pool_uses_indirect_client COMMENT: on|off TYPE: onoff IFDEF: FOLLOW_X_FORWARDED_FOR && 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 COMMENT_START NETWORK OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: http_port ascii_port TYPE: http_port_list DEFAULT: none LOC: Config.Sockaddr.http DOC_START Usage: port [options] hostname:port [options] 1.2.3.4:port [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. This replaces the old 'tcp_incoming_address' option. 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. You may specify multiple socket addresses on multiple lines. Options: transparent Support for transparent interception of outgoing requests without browser settings. tproxy Support Linux TPROXY for spoofing outgoing connections using the client IP address. accel Accelerator mode. Also needs at least one of vhost/vport/defaultsite. 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. Implies accel. vhost Accelerator mode using Host header for virtual domain support. Implies accel. vport Accelerator with IP based virtual host support. Implies accel. vport=NN As above, but uses specified port number rather than the http_port number. Implies accel. urlgroup= Default urlgroup to mark requests with (see also acl urlgroup and url_rewrite_program) protocol= Protocol to reconstruct accelerated requests with. Defaults to http. no-connection-auth Prevent forwarding of Microsoft connection oriented authentication (NTLM, Negotiate and Kerberos) 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_SSL TYPE: https_port_list DEFAULT: none LOC: Config.Sockaddr.https DOC_START Usage: [ip:]port cert=certificate.pem [key=key.pem] [options...] The socket address where Squid will listen for HTTPS client requests. This is really only useful for situations where you are running squid in accelerator mode and you want to do the SSL work at the accelerator level. You may specify multiple socket addresses on multiple lines, each with their own SSL certificate and/or options. Options: accel Accelerator mode. Also needs at least one of defaultsite or vhost. defaultsite= The name of the https site presented on this port. Implies accel. vhost Accelerator mode using Host header for virtual domain support. Requires a wildcard certificate or other certificate valid for more than one domain. Implies accel. urlgroup= Default urlgroup to mark requests with (see also acl urlgroup and url_rewrite_program). protocol= Protocol to reconstruct accelerated requests with. Defaults to https. cert= Path to SSL certificate (PEM format). key= Path to SSL private key file (PEM format) if not specified, the certificate file is assumed to be a combined certificate and key file. version= The version of SSL/TLS supported 1 automatic (default) 2 SSLv2 only 3 SSLv3 only 4 TLSv1 only cipher= Colon separated list of supported ciphers. options= Various SSL engine options. The most important being: NO_SSLv2 Disallow the use of SSLv2 NO_SSLv3 Disallow the use of SSLv3 NO_TLSv1 Disallow the use of TLSv1 SINGLE_DH_USE Always create a new key when using temporary/ephemeral DH key exchanges See src/ssl_support.c or OpenSSL SSL_CTX_set_options documentation for a complete list of options. clientca= File containing the list of CAs to use when requesting a client certificate. cafile= File containing additional CA certificates to use when verifying client certificates. If unset clientca will be used. capath= Directory containing additional CA certificates and CRL lists to use when verifying client certificates. 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. dhparams= File containing DH parameters for temporary/ephemeral DH key exchanges. 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). NO_DEFAULT_CA Don't use the default CA lists built in to OpenSSL. 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. sslcontext= SSL session ID context identifier. vport Accelerator with IP based virtual host support. vport=NN As above, but uses specified port number rather than the https_port number. Implies accel. DOC_END NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp TYPE: acl_tos DEFAULT: none LOC: Config.accessList.outgoing_tos DOC_START Allows you to select a TOS/Diffserv value to mark outgoing connections with, based on the username or source address making the request. 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 10.0.0.0/255.255.255.0 acl good_service_net src 10.0.1.0/255.255.255.0 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 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 in practice often only values 0 - 63 is usable as the two highest bits have been redefined for use by ECN (RFC3168). Processing proceeds in the order specified, and stops at first fully matching line. 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_persisten_connections to off when using this directive in such configurations. DOC_END NAME: tcp_outgoing_address TYPE: acl_address DEFAULT: none 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] ... Example where requests from 10.0.0.0/24 will be forwarded with source address 10.1.0.1, 10.0.2.0/24 forwarded with source address 10.1.0.2 and the rest will be forwarded with source address 10.1.0.3. acl normal_service_net src 10.0.0.0/24 acl good_service_net src 10.0.1.0/24 10.0.2.0/24 tcp_outgoing_address 10.1.0.1 normal_service_net tcp_outgoing_address 10.1.0.2 good_service_net tcp_outgoing_address 10.1.0.3 Processing proceeds in the order specified, and stops at first fully matching line. 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. DOC_END COMMENT_START SSL OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: ssl_unclean_shutdown IFDEF: USE_SSL 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_SSL 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. DOC_END NAME: sslproxy_client_certificate IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.cert TYPE: string DOC_START Client SSL Certificate to use when proxying https:// URLs DOC_END NAME: sslproxy_client_key IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.key TYPE: string DOC_START Client SSL Key to use when proxying https:// URLs DOC_END NAME: sslproxy_version IFDEF: USE_SSL DEFAULT: 1 LOC: Config.ssl_client.version TYPE: int DOC_START SSL version level to use when proxying https:// URLs DOC_END NAME: sslproxy_options IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.options TYPE: string DOC_START SSL engine options to use when proxying https:// URLs DOC_END NAME: sslproxy_cipher IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.cipher TYPE: string DOC_START SSL cipher list to use when proxying https:// URLs DOC_END NAME: sslproxy_cafile IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.cafile TYPE: string DOC_START file containing CA certificates to use when verifying server certificates while proxying https:// URLs DOC_END NAME: sslproxy_capath IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.capath TYPE: string DOC_START directory containing CA certificates to use when verifying server certificates while proxying https:// URLs DOC_END NAME: sslproxy_flags IFDEF: USE_SSL DEFAULT: none LOC: Config.ssl_client.flags TYPE: string DOC_START Various flags modifying the use of SSL while proxying https:// URLs: DONT_VERIFY_PEER Accept certificates even if they fail to verify. NO_DEFAULT_CA Don't use the default CA list built in to OpenSSL. DOC_END NAME: sslpassword_program IFDEF: USE_SSL 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. 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 proxy-only default cache_peer sib1.foo.net sibling 3128 3130 proxy-only cache_peer sib2.foo.net sibling 3128 3130 proxy-only type: either 'parent', 'sibling', or 'multicast'. proxy-port: The port number where the cache listens for proxy requests. icp-port: Used for querying neighbor caches about objects. To have a non-ICP neighbor specify '7' for the ICP port and make sure the neighbor machine has the UDP echo port enabled in its /etc/inetd.conf file. NOTE: Also requires icp_port option enabled to send/receive requests via this method. options: proxy-only weight=n ttl=n no-query default round-robin carp multicast-responder closest-only no-digest no-netdb-exchange no-delay login=user:password | PASS | *:password connect-timeout=nn digest-url=url allow-miss max-conn=n htcp htcp-oldsquid originserver userhash sourcehash name=xxx monitorurl=url monitorsize=sizespec monitorinterval=seconds monitortimeout=seconds forceddomain=name ssl sslcert=/path/to/ssl/certificate sslkey=/path/to/ssl/key sslversion=1|2|3|4 sslcipher=... ssloptions=... front-end-https[=on|auto] connection-auth[=on|off|auto] use 'proxy-only' to specify objects fetched from this cache should not be saved locally. use 'weight=n' 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. use 'ttl=n' to specify a IP multicast TTL to use when sending an 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 below. use 'no-query' to NOT send ICP queries to this neighbor. use 'default' if 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 mechanisms. If specified more than once, only the first is used. use 'round-robin' to define a set of parents which should be used in a round-robin fashion in the absence of any ICP queries. use 'carp' to define a set of 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. '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. use 'no-digest' to NOT request cache digests from this neighbor. 'no-netdb-exchange' disables requesting ICMP RTT database (NetDB) from the neighbor. use 'no-delay' to prevent access to this neighbor from influencing the delay pools. use '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 %%. use 'login=PASS' if users must authenticate against the upstream proxy or in the case of a reverse proxy configuration, the origin web server. This will pass the users credentials as they are to the peer. Note: To combine this with local authentication the Basic authentication scheme must be used, and both servers 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 use 'login=*:password' to pass 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. use 'connect-timeout=nn' to specify a peer specific connect timeout (also see the peer_connect_timeout directive) use 'digest-url=url' to tell Squid to fetch the cache digest (if digests are enabled) for this host from the specified URL rather than the Squid default location. use 'allow-miss' to 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. To extensive use of this option may result in forwarding loops, and you should avoid having two-way peerings with this option. (for example to deny peer usage on requests from peer by denying cache_peer_access if the source is a peer) use 'max-conn=n' to limit the amount of connections Squid may open to this peer. use 'htcp' to send HTCP, instead of ICP, queries to the neighbor. You probably also want to set the "icp port" to 4827 instead of 3130. You must also allow this Squid htcp_access and http_access in the peer Squid configuration. use 'htcp-oldsquid' to send HTCP to old Squid versions You must also allow this Squid htcp_access and http_access in the peer Squid configuration. 'originserver' causes this parent peer to be contacted as a origin server. Meant to be used in accelerator setups. use 'userhash' to load-balance amongst a set of parents based on the client proxy_auth or ident username. use 'sourcehash' to load-balance amongst a set of parents based on the client source ip. use 'name=xxx' if you have multiple peers on the same host but different ports. This name can be used to differentiate the peers in cache_peer_access and similar directives. use 'monitorurl=url' to have periodically request a given URL from the peer, and only consider the peer as alive if this monitoring is successful (default none) use 'monitorsize=min[-max]' to limit the size range of 'monitorurl' replies considered valid. Defaults to 0 to accept any size replies as valid. use 'monitorinterval=seconds' to change frequency of how often the peer is monitored with 'monitorurl' (default 300 for a 5 minute interval). If set to 0 then monitoring is disabled even if a URL is defined. use 'monitortimeout=seconds' to change the timeout of 'monitorurl'. Defaults to 'monitorinterval'. use 'forceddomain=name' to forcibly set the Host header of requests forwarded to this peer. Useful in accelerator setups where the server (peer) expects a certain domain name and using redirectors to feed this domain name is not feasible. use 'ssl' to indicate connections to this peer should be SSL/TLS encrypted. use 'sslcert=/path/to/ssl/certificate' to specify a client SSL certificate to use when connecting to this peer. use 'sslkey=/path/to/ssl/key' to specify the private SSL key corresponding to sslcert above. If 'sslkey' is not specified 'sslcert' is assumed to reference a combined file containing both the certificate and the key. use sslversion=1|2|3|4 to specify the SSL version to use when connecting to this peer 1 = automatic (default) 2 = SSL v2 only 3 = SSL v3 only 4 = TLS v1 only use sslcipher=... to specify the list of valid SSL ciphers to use when connecting to this peer. use ssloptions=... to specify various SSL engine options: NO_SSLv2 Disallow the use of SSLv2 NO_SSLv3 Disallow the use of SSLv3 NO_TLSv1 Disallow the use of TLSv1 See src/ssl_support.c or the OpenSSL documentation for a more complete list. use sslcafile=... to specify a file containing additional CA certificates to use when verifying the peer certificate. use sslcapath=... to specify a directory containing additional CA certificates to use when verifying the peer certificate. use sslcrlfile=... to specify a certificate revocation list file to use when verifying the peer certificate. use sslflags=... to specify various flags modifying the SSL implementation: DONT_VERIFY_PEER Accept certificates even if they fail to verify. NO_DEFAULT_CA Don't use the default CA list built in to OpenSSL. use ssldomain= to specify 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. use front-end-https to 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. use connection-auth=off to tell Squid that this peer does 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. DOC_END NAME: cache_peer_domain cache_host_domain TYPE: hostdomain DEFAULT: none LOC: none DOC_START Use to limit the domains for which a neighbor cache will be queried. Usage: cache_peer_domain cache-host domain [domain ...] cache_peer_domain cache-host !domain For example, specifying cache_peer_domain parent.foo.net .edu has the effect such that UDP query packets are sent to 'bigserver' only when the requested object exists on a server in the .edu domain. Prefixing the domain name with '!' means the cache will be queried for objects NOT in that domain. NOTE: * Any number of domains may be given for a cache-host, either on the same or separate lines. * When multiple domains are given for a particular cache-host, the first matched domain is applied. * Cache hosts with no domain restrictions are queried for all requests. * There are no defaults. * There is also a 'cache_peer_access' tag in the ACL section. DOC_END NAME: cache_peer_access TYPE: peer_access DEFAULT: none LOC: none DOC_START Similar to 'cache_peer_domain' but provides more flexibility by using ACL elements. cache_peer_access cache-host allow|deny [!]aclname ... The syntax is identical to 'http_access' and the other lists of ACL elements. See the comments for 'http_access' below, or the Squid FAQ (http://www.squid-cache.org/FAQ/FAQ-10.html). DOC_END NAME: neighbor_type_domain TYPE: hostdomaintype DEFAULT: none LOC: none DOC_START usage: neighbor_type_domain neighbor parent|sibling domain domain ... Modifying the neighbor type for specific domains is now possible. You can treat some domains differently than the the default neighbor type specified on the 'cache_peer' line. Normally it should only be necessary to list domains which should be treated differently because the default neighbor type applies for hostnames which do not match domains listed here. EXAMPLE: cache_peer cache.foo.org parent 3128 3130 neighbor_type_domain cache.foo.org sibling .com .net neighbor_type_domain cache.foo.org sibling .au .de 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: hierarchy_stoplist TYPE: wordlist DEFAULT: none LOC: Config.hierarchy_stoplist DOC_START A list of words which, if found in a URL, cause the object to be handled directly by this cache. In other words, use this to not query neighbor caches for certain objects. You may list this option multiple times. Note: never_direct overrides this option. NOCOMMENT_START #We recommend you to use at least the following line. hierarchy_stoplist cgi-bin ? NOCOMMENT_END DOC_END COMMENT_START MEMORY CACHE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: cache_mem COMMENT: (bytes) TYPE: b_size_t DEFAULT: 8 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. DOC_END NAME: maximum_object_size_in_memory COMMENT: (bytes) TYPE: b_size_t DEFAULT: 8 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_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. 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. 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 4096 KB 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: cache_dir TYPE: cachedir DEFAULT: none DEFAULT_IF_NONE: ufs @DEFAULT_SWAP_DIR@ 100 16 256 LOC: Config.cacheSwap DOC_START Usage: 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. Only using COSS, a raw disk device or a stripe file can be specified, but the configuration of the "cache_swap_log" tag is mandatory. The ufs store type: "ufs" is the old well-known Squid storage format that has always been there. 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. 'Level-1' is the number of first-level subdirectories which will be created under the 'Directory'. The default is 16. 'Level-2' 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. 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. 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 coss store type: block-size=n defines the "block size" for COSS cache_dir's. Squid uses file numbers as block numbers. Since file numbers are limited to 24 bits, the block size determines the maximum size of the COSS partition. The default is 512 bytes, which leads to a maximum cache_dir size of 512<<24, or 8 GB. Note you should not change the COSS block size after Squid has written some objects to the cache_dir. overwrite-percent=n defines the percentage of disk that COSS must write to before a given object will be moved to the current stripe. A value of "n" closer to 100 will cause COSS to waste less disk space by having multiple copies of an object on disk, but will increase the chances of overwriting a popular object as COSS overwrites stripes. A value of "n" close to 0 will cause COSS to keep all current objects in the current COSS stripe at the expense of the hit rate. The default value of 50 will allow any given object to be stored on disk a maximum of 2 times. max-stripe-waste=n defines the maximum amount of space that COSS will waste in a given stripe (in bytes). When COSS writes data to disk, it will potentially waste up to "max-size" worth of disk space for each 1MB of data written. If "max-size" is set to a large value (ie >256k), this could potentially result in large amounts of wasted disk space. Setting this value to a lower value (ie 64k or 32k) will result in a COSS disk refusing to cache larger objects until the COSS stripe has been filled to within "max-stripe-waste" of the maximum size (1MB). membufs=n defines the number of "memory-only" stripes that COSS will use. When an cache hit is performed on a COSS stripe before COSS has reached the overwrite-percent value for that object, COSS will use a series of memory buffers to hold the object in while the data is sent to the client. This will define the maximum number of memory-only buffers that COSS will use. The default value is 10, which will use a maximum of 10MB of memory for buffers. maxfullbufs=n defines the maximum number of stripes a COSS partition will have in memory waiting to be freed (either because the disk is under load and the stripe is unwritten, or because clients are still transferring data from objects using the memory). In order to try and maintain a good hit rate under load, COSS will reserve the last 2 full stripes for object hits. (ie a COSS cache_dir will reject new objects when the number of full stripes is 2 less than maxfullbufs) The null store type: no options are allowed or required Common options: read-only, no new objects should be stored to this cache_dir min-size=n, refers to the min object size this storedir will accept. It's used to restrict a storedir to only store large objects (e.g. aufs) while other storedirs are optimized for smaller objects (e.g. COSS). Defaults to 0. max-size=n, refers to the max object size this storedir supports. It is used to initially choose the storedir to dump the object. Note: To make optimal use of the max-size limits you should order the cache_dir lines with the smallest max-size value first and the ones with no max-size specification last. Note that for coss, max-size must be less than COSS_MEMBUF_SZ (hard coded at 1 MB). DOC_END NAME: store_dir_select_algorithm TYPE: string LOC: Config.store_dir_select_algorithm DEFAULT: least-load DOC_START Set this to 'round-robin' as an alternative. DOC_END NAME: max_open_disk_fds TYPE: int LOC: Config.max_open_disk_fds DEFAULT: 0 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: minimum_object_size COMMENT: (bytes) TYPE: b_size_t DEFAULT: 0 KB LOC: Config.Store.minObjectSize DOC_START Objects smaller than this size will NOT be saved on disk. The value is specified in kilobytes, and the default is 0 KB, which means there is no minimum. DOC_END NAME: maximum_object_size COMMENT: (bytes) TYPE: b_size_t DEFAULT: 4096 KB LOC: Config.Store.maxObjectSize DOC_START Objects larger than this size will NOT be saved on disk. The value is specified in kilobytes, and the default is 4MB. 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 speed more than your 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 replacement_policy below for a discussion of this policy. DOC_END NAME: cache_swap_low COMMENT: (percent, 0-100) TYPE: int DEFAULT: 90 LOC: Config.Swap.lowWaterMark DOC_NONE NAME: cache_swap_high COMMENT: (percent, 0-100) TYPE: int DEFAULT: 95 LOC: Config.Swap.highWaterMark DOC_START The low- and high-water marks for cache object replacement. Replacement begins when the swap (disk) usage is above the low-water mark and attempts to maintain utilization near the low-water mark. As swap utilization gets close to high-water mark object eviction becomes more aggressive. If utilization is close to the low-water mark less replacement is done each time. 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. DOC_END COMMENT_START LOGFILE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: logformat TYPE: logformat LOC: Config.Log.logformats DEFAULT: none 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 but the formatcode is optional. Output strings are automatically escaped as required according to their context and the output format modifiers are usually not needed, but can be specified if an explicit output format is desired. % ["|[|'|#] [-] [[0]width] [{argument}] formatcode " output in quoted string format [ output in squid text log format as used by log_mime_hdrs # output in URL quoted format ' output as-is - left aligned width field width. If starting with 0 the output is zero padded {arg} argument such as header name etc Format codes: >a Client source IP address >A Client FQDN >p Client source port h Request header. Optional header name argument on the format header[:[separator]element] h un User name ul User name from authentication ui User name from ident us User name from SSL ue User name from external acl helper Hs HTTP status code Ss Squid request status (TCP_MISS etc) Sh Squid hierarchy status (DEFAULT_PARENT etc) mt MIME content type rm Request method (GET/POST etc) ru Request URL rv Request protocol version ea Log string returned by external acl st Request size including HTTP headers st Request+Reply size including HTTP headers % a literal % character The default formats available (which do not need re-defining) are: logformat squid %ts.%03tu %6tr %>a %Ss/%03Hs %a %Ss/%03Hs %h] [%a %ui %un [%tl] "%rm %ru HTTP/%rv" %Hs %a %ui %un [%tl] "%rm %ru HTTP/%rv" %Hs %h" "%{User-Agent}>h" %Ss:%Sh DOC_END NAME: access_log cache_access_log TYPE: access_log LOC: Config.Log.accesslogs DEFAULT: none DOC_START These files log client request activities. Has a line every HTTP or ICP request. The format is: access_log [ [acl acl ...]] access_log none [acl acl ...]] Will log to the specified file 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 file. To disable logging of a request use the filepath "none", in which case a logformat name should not be specified. To log the request via syslog specify a filepath of "syslog": access_log syslog[:facility.priority] [format [acl1 [acl2 ....]]] where facility could be any of: authpriv, daemon, local0 .. local7 or user. And priority could be any of: err, warning, notice, info, debug. Note: 2.6.STABLE14 and earlier only supports a slightly different and undocumented format with all uppercase LOG_FACILITY|LOG_PRIORITY NOCOMMENT_START access_log @DEFAULT_ACCESS_LOG@ squid NOCOMMENT_END DOC_END NAME: log_access TYPE: acl_access LOC: Config.accessList.log DEFAULT: none COMMENT: allow|deny acl acl... DOC_START This options allows you to control which requests gets logged to access.log (see access_log directive). Requests denied for logging will also not be accounted for in performance counters. DOC_END NAME: cache_log TYPE: string DEFAULT: @DEFAULT_CACHE_LOG@ LOC: Config.Log.log DOC_START Cache logging file. This is where general information about your cache's behavior goes. You can increase the amount of data logged to this file with the "debug_options" tag below. DOC_END NAME: cache_store_log TYPE: string DEFAULT: @DEFAULT_STORE_LOG@ 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. To disable, enter "none". There are not really utilities to analyze this data, so you can safely disable it. DOC_END NAME: cache_swap_state cache_swap_log TYPE: string LOC: Config.Log.swap DEFAULT: none 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 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, 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: emulate_httpd_log COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.common_log DOC_START The Cache can emulate the log file format which many 'httpd' programs use. To disable/enable this emulation, set emulate_httpd_log to 'off' or 'on'. The default is to use the native log format since it includes useful information Squid-specific log analyzers use. DOC_END NAME: log_ip_on_direct COMMENT: on|off TYPE: onoff DEFAULT: on LOC: Config.onoff.log_ip_on_direct DOC_START Log the destination IP address in the hierarchy log tag when going direct. Earlier Squid versions logged the hostname here. If you prefer the old way set this to off. DOC_END NAME: mime_table TYPE: string DEFAULT: @DEFAULT_MIME_TABLE@ LOC: Config.mimeTablePathname DOC_START Pathname to Squid's MIME table. 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: useragent_log TYPE: string LOC: Config.Log.useragent DEFAULT: none IFDEF: USE_USERAGENT_LOG DOC_START Squid will write the User-Agent field from HTTP requests to the filename specified here. By default useragent_log is disabled. DOC_END NAME: referer_log referrer_log TYPE: string LOC: Config.Log.referer DEFAULT: none IFDEF: USE_REFERER_LOG DOC_START Squid will write the Referer field from HTTP requests to the filename specified here. By default referer_log is disabled. Note that "referer" is actually a misspelling of "referrer" however the misspelt version has been accepted into the HTTP RFCs and we accept both. 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: debug_options TYPE: eol DEFAULT: ALL,1 LOC: Config.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. We recommend normally running with "ALL,1". DOC_END NAME: log_fqdn COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.log_fqdn DOC_START Turn this on if you wish to log fully qualified domain names in the access.log. To do this Squid does a DNS lookup of all IP's connecting to it. This can (in some situations) increase latency, which makes your cache seem slower for interactive browsing. DOC_END NAME: client_netmask TYPE: address LOC: Config.Addrs.client_netmask DEFAULT: 255.255.255.255 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: forward_log IFDEF: WIP_FWD_LOG TYPE: string DEFAULT: none LOC: Config.Log.forward DOC_START Logs the server-side requests. This is currently work in progress. 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. DOC_END NAME: buffered_logs COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.buffered_logs DOC_START cache.log log file is written with stdio functions, and as such it can be buffered or unbuffered. By default it will be unbuffered. Buffering it can speed up the writing slightly (though you are unlikely to need to worry unless you run with tons of debugging enabled in which case performance will suffer badly anyway..). 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_list_width TYPE: int DEFAULT: 32 LOC: Config.Ftp.list_width DOC_START Sets the width of ftp listings. This should be set to fit in the width of a standard browser. Setting this too small can cut off long filenames when browsing ftp sites. 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. 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 TYPE: string DEFAULT: @DEFAULT_PINGER@ LOC: Config.Program.pinger IFDEF: USE_ICMP DOC_START Specify the location of the executable for the pinger process. DOC_END COMMENT_START OPTIONS FOR URL REWRITING ----------------------------------------------------------------------------- COMMENT_END NAME: url_rewrite_program redirect_program TYPE: programline LOC: Config.Program.url_rewrite.command DEFAULT: none DOC_START Specify the location of the executable for the URL rewriter. Since they can perform almost any function there isn't one included. For each requested URL rewriter will receive on line with the format URL client_ip "/" fqdn user method urlgroup And the rewriter may return a rewritten URL. The other components of the request line does not need to be returned (ignored if they are). The rewriter can also indicate that a client-side redirect should be performed to the new URL. This is done by prefixing the returned URL with "301:" (moved permanently) or 302: (moved temporarily). It can also return a "urlgroup" that can subsequently be matched in cache_peer_access and similar ACL driven rules. An urlgroup is returned by prefixing the returned URL with "!urlgroup!". By default, a URL rewriter is not used. DOC_END NAME: url_rewrite_children redirect_children TYPE: int DEFAULT: 5 LOC: Config.Program.url_rewrite.children DOC_START The number of redirector processes to spawn. If you start too few Squid will have to wait for them to process a backlog of URLs, slowing it down. If you start too many they will use RAM and other system resources. DOC_END NAME: url_rewrite_concurrency redirect_concurrency TYPE: int DEFAULT: 0 LOC: Config.Program.url_rewrite.concurrency DOC_START 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 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. DOC_END NAME: url_rewrite_host_header redirect_rewrites_host_header TYPE: onoff DEFAULT: on LOC: Config.onoff.redir_rewrites_host DOC_START By default Squid rewrites any Host: header in redirected requests. If you are running an accelerator this may not be a wanted effect of a redirector. WARNING: Entries are cached on the result of the URL rewriting process, so be careful if you have domain-virtual hosts. DOC_END NAME: url_rewrite_access redirector_access TYPE: acl_access DEFAULT: none LOC: Config.accessList.url_rewrite DOC_START If defined, this access list specifies which requests are sent to the redirector processes. By default all requests are sent. DOC_END NAME: 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 redirectors are busy. If this is 'off' and the redirector queue grows too large, Squid will exit with a FATAL error and ask you to increase the number of redirectors. 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. DOC_END NAME: location_rewrite_program TYPE: programline LOC: Config.Program.location_rewrite.command DEFAULT: none DOC_START Specify the location of the executable for the Location rewriter, used to rewrite server generated redirects. Usually used in conjunction with a url_rewrite_program For each Location header received the location rewriter will receive one line with the format: location URL requested URL urlgroup And the rewriter may return a rewritten Location URL or a blank line. The other components of the request line does not need to be returned (ignored if they are). By default, a Location rewriter is not used. DOC_END NAME: location_rewrite_children TYPE: int DEFAULT: 5 LOC: Config.Program.location_rewrite.children DOC_START The number of location rewriting processes to spawn. If you start too few Squid will have to wait for them to process a backlog of URLs, slowing it down. If you start too many they will use RAM and other system resources. DOC_END NAME: location_rewrite_concurrency TYPE: int DEFAULT: 0 LOC: Config.Program.location_rewrite.concurrency DOC_START The number of requests each Location rewriter helper can handle in parallel. Defaults to 0 which indicates that the helper is a old-style singlethreaded helper. DOC_END NAME: location_rewrite_access TYPE: acl_access DEFAULT: none LOC: Config.accessList.location_rewrite DOC_START If defined, this access list specifies which requests are sent to the location rewriting processes. By default all Location headers are sent. DOC_END COMMENT_START OPTIONS FOR TUNING THE CACHE ----------------------------------------------------------------------------- COMMENT_END NAME: cache no_cache TYPE: acl_access DEFAULT: none LOC: Config.accessList.noCache DOC_START A list of ACL elements which, if matched, cause the request to not be satisfied from the cache and the reply to not be cached. In other words, use this to force certain objects to never be cached. You must use the word 'DENY' to indicate the ACL names which should NOT be cached. Default is to allow all to be cached NOCOMMENT_START #We recommend you to use the following two lines. acl QUERY urlpath_regex cgi-bin \? cache deny QUERY NOCOMMENT_END 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 a percentage of the objects age (time since last modification age) an object without explicit expiry time will be considered fresh. 'Max' is an upper limit on how long objects without an explicit expiry time will be considered fresh. options: override-expire override-lastmod reload-into-ims ignore-reload ignore-no-cache ignore-private ignore-auth override-expire enforces min age even if the server sent a Expires: header. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. Note: this 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 client no-cache or ``reload'' to If-Modified-Since requests. 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-cache ignores any ``Pragma: no-cache'' and ``Cache-control: no-cache'' headers received from a server. The HTTP RFC never allows the use of this (Pragma) header from a server, only a client, though plenty of servers send it anyway. 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. ignore-auth caches responses to requests with authorization, as if the originserver had sent ``Cache-control: public'' in the response header. Doing this VIOLATES the HTTP standard. Enabling this feature could make you liable for problems which it causes. Basically a cached object is: FRESH if expires < 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. Suggested default: NOCOMMENT_START refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern . 0 20% 4320 NOCOMMENT_END DOC_END NAME: quick_abort_min COMMENT: (KB) TYPE: kb_size_t DEFAULT: 16 KB LOC: Config.quickAbort.min DOC_NONE NAME: quick_abort_max COMMENT: (KB) TYPE: kb_size_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 transfered 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_size_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 COMMENT: time-units TYPE: time_t LOC: Config.negativeTtl DEFAULT: 5 minutes DOC_START Time-to-Live (TTL) for failed requests. Certain types of failures (such as "connection refused" and "404 Not Found") are negatively-cached for a configurable amount of time. The default is 5 minutes. Note that this is different from negative caching of DNS lookups. 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 minute 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: (bytes) TYPE: b_size_t LOC: Config.rangeOffsetLimit DEFAULT: 0 KB DOC_START Sets a upper limit on how far into the 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. A value of -1 causes Squid to always fetch the object from the beginning so it may cache the result. (2.0 style) A value of 0 causes Squid to never fetch more than the client requested. (default) 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 defaults to 60 seconds. In reverse proxy enorinments 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. DOC_END NAME: store_avg_object_size COMMENT: (kbytes) TYPE: kb_size_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. 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: 20 KB LOC: Config.maxRequestHeaderSize DOC_START This specifies the maximum size for HTTP headers in a request. Request headers are usually relatively small (about 512 bytes). Placing a limit on the request header size will catch certain bugs (for example with persistent connections) and possibly buffer-overflow or denial-of-service attacks. DOC_END NAME: reply_header_max_size COMMENT: (KB) TYPE: b_size_t DEFAULT: 20 KB LOC: Config.maxReplyHeaderSize DOC_START This specifies the maximum size for HTTP headers in a reply. Reply headers are usually relatively small (about 512 bytes). Placing a limit on the reply header size will catch certain bugs (for example with persistent connections) and possibly buffer-overflow or denial-of-service attacks. DOC_END NAME: request_body_max_size COMMENT: (KB) TYPE: b_size_t DEFAULT: 0 KB 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. DOC_END NAME: broken_posts TYPE: acl_access DEFAULT: none 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. Example: acl buggy_server url_regex ^http://.... broken_posts allow buggy_server DOC_END NAME: via IFDEF: 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: cache_vary TYPE: onoff DEFAULT: on LOC: Config.onoff.cache_vary DOC_START When 'cache_vary' is set to off, response that have a Vary header will not be stored in the cache. DOC_END NAME: broken_vary_encoding TYPE: acl_access DEFAULT: none LOC: Config.accessList.vary_encoding DOC_START Many servers have broken support for on-the-fly Content-Encoding, returning the same ETag on both plain and gzip:ed variants. Vary replies matching this access list will have the cache split on the Accept-Encoding header of the request and not trusting the ETag to be unique. NOCOMMENT_START # Apache mod_gzip and mod_deflate known to be broken so don't trust # Apache to signal ETag correctly on such responses acl apache rep_header Server ^Apache broken_vary_encoding allow apache NOCOMMENT_END DOC_END NAME: collapsed_forwarding COMMENT: (on|off) TYPE: onoff LOC: Config.onoff.collapsed_forwarding DEFAULT: off DOC_START This option enables multiple requests for the same URI to be processed as one request. Normally disabled to avoid increased latency on dynamic content, but there can be benefit from enabling this in accelerator setups where the web servers are the bottleneck and reliable and returns mostly cacheable information. DOC_END NAME: refresh_stale_hit COMMENT: (time) TYPE: time_t DEFAULT: 0 seconds LOC: Config.refresh_stale_window DOC_START This option changes the refresh algorithm to allow concurrent requests while an object is being refreshed to be processed as cache hits if the object expired less than X seconds ago. Default is 0 to disable this feature. This option is mostly interesting in accelerator setups where a few objects is accessed very frequently. DOC_END NAME: ie_refresh COMMENT: on|off TYPE: onoff LOC: Config.onoff.ie_refresh DEFAULT: off DOC_START Microsoft Internet Explorer up until version 5.5 Service Pack 1 has an issue with transparent proxies, wherein it is impossible to force a refresh. Turning this on provides a partial fix to the problem, by causing all IMS-REFRESH requests from older IE versions to check the origin server for fresh content. This reduces hit ratio by some amount (~10% in my experience), but allows users to actually get fresh content when they want it. Note because Squid cannot tell if the user is using 5.5 or 5.5SP1, the behavior of 5.5 is unchanged from old versions of Squid (i.e. a forced refresh is impossible). Newer versions of IE will, hopefully, continue to have the new behavior and will be handled based on that assumption. This option defaults to the old Squid behavior, which is better for hit ratios but worse for clients using IE, if they need to be able to force fresh content. 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: This may eventually cause some varying objects not intended for caching to get cached. DOC_END NAME: extension_methods TYPE: extension_method LOC: RequestMethodStr DEFAULT: none DOC_START Squid only knows about standardized HTTP request methods. You can add up to 20 additional "extension" methods here. 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: header_access IFDEF: HTTP_VIOLATIONS TYPE: http_header_access[] LOC: Config.header_access DEFAULT: none DOC_START Usage: 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. This new method creates a list of ACLs for each header, allowing you very fine-tuned header mangling. You can only specify known headers for the header name. Other headers are reclassified as 'Other'. You can also refer to all the headers with 'All'. For example, to achieve the same behavior as the old 'http_anonymizer standard' option, you should use: header_access From deny all header_access Referer deny all header_access Server deny all header_access User-Agent deny all header_access WWW-Authenticate deny all header_access Link deny all Or, to reproduce the old 'http_anonymizer paranoid' feature you should use: header_access Allow allow all header_access Authorization allow all header_access WWW-Authenticate allow all header_access Proxy-Authorization allow all header_access Proxy-Authenticate allow all header_access Cache-Control allow all header_access Content-Encoding allow all header_access Content-Length allow all header_access Content-Type allow all header_access Date allow all header_access Expires allow all header_access Host allow all header_access If-Modified-Since allow all header_access Last-Modified allow all header_access Location allow all header_access Pragma allow all header_access Accept allow all header_access Accept-Charset allow all header_access Accept-Encoding allow all header_access Accept-Language allow all header_access Content-Language allow all header_access Mime-Version allow all header_access Retry-After allow all header_access Title allow all header_access Connection allow all header_access Proxy-Connection allow all header_access All deny all By default, all headers are allowed (no anonymizing is performed). DOC_END NAME: header_replace IFDEF: HTTP_VIOLATIONS TYPE: http_header_replace[] LOC: Config.header_access DEFAULT: none DOC_START Usage: header_replace header_name message Example: header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit) This option allows you to change the contents of headers denied with header_access above, by replacing them with some fixed string. This replaces the old fake_user_agent option. By default, headers are removed if denied. 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 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 The read_timeout is applied on server-side 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: request_timeout TYPE: time_t LOC: Config.Timeout.request DEFAULT: 5 minutes DOC_START How long to wait for an HTTP request after initial connection establishment. DOC_END NAME: persistent_request_timeout TYPE: time_t LOC: Config.Timeout.persistent_request DEFAULT: 2 minutes DOC_START How long to wait for the next HTTP request on a persistent connection after the previous request completes. 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: half_closed_clients TYPE: onoff LOC: Config.onoff.half_closed_clients DEFAULT: on 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, half-closed client connections are kept open until a read(2) or write(2) on the socket returns an error. Change this option to 'off' and Squid will immediately close client connections when read(2) returns "no more data to read." DOC_END NAME: pconn_timeout TYPE: time_t LOC: Config.Timeout.pconn 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: Config.Timeout.ident 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 'appname@unique_hostname'. Default appname value is "squid", can be changed into src/globals.h before building squid. 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: nobody 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 to nobody. If you define cache_effective_user, but not cache_effective_group, Squid sets the GID to the effective user's default group ID (taken from the password file) and supplementary group list from the from groups membership of cache_effective_user. DOC_END NAME: cache_effective_group TYPE: string DEFAULT: none LOC: Config.effectiveGroup DOC_START 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 is 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. 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 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 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. Note: Should start with a 0 to indicate the normal octal representation of umasks 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 DOC_START This is how frequently to send cache announcements. The default is `0' which disables sending the announcement messages. To enable announcing your cache, just uncomment the line below. NOCOMMENT_START #To enable announcing your cache, just uncomment the line below. #announce_period 1 day NOCOMMENT_END DOC_END NAME: announce_host TYPE: string DEFAULT: tracker.ircache.net LOC: Config.Announce.host DOC_NONE NAME: announce_file TYPE: string DEFAULT: none LOC: Config.Announce.file DOC_NONE NAME: announce_port TYPE: ushort DEFAULT: 3131 LOC: Config.Announce.port DOC_START announce_host and announce_port set the hostname and port number where the registration message will be sent. Hostname will default to 'tracker.ircache.net' and port will default default to 3131. If the 'filename' argument is given, the contents of that file will be included in the announce message. DOC_END COMMENT_START HTTPD-ACCELERATOR OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: httpd_accel_no_pmtu_disc COMMENT: on|off TYPE: onoff DEFAULT: off LOC: Config.onoff.accel_no_pmtu_disc DOC_START 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 this to on. DOC_END COMMENT_START DELAY POOL PARAMETERS ----------------------------------------------------------------------------- COMMENT_END NAME: delay_pools TYPE: delay_pool_count DEFAULT: 0 IFDEF: 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. DOC_END NAME: delay_class TYPE: delay_pool_class DEFAULT: none IFDEF: 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 2 # 2 delay pools delay_class 1 2 # pool 1 is a class 2 pool delay_class 2 3 # pool 2 is a class 3 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 IP 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 IP address. 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" DOC_END NAME: delay_access TYPE: delay_pool_access DEFAULT: none IFDEF: 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: Example: delay_access 1 allow some_big_clients delay_access 1 deny all delay_access 2 allow lotsa_little_clients delay_access 2 deny all DOC_END NAME: delay_parameters TYPE: delay_pool_rates DEFAULT: none IFDEF: 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_parameters pool aggregate For a class 2 delay pool: delay_parameters pool aggregate individual For a class 3 delay pool: delay_parameters pool aggregate network individual The variables here 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 "delay parameters" for the aggregate bucket (class 1, 2, 3). individual the "delay parameters" for the individual buckets (class 2, 3). network the "delay parameters" for the network buckets (class 3). 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. 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 64kbps (plus overheads), with no overall limit, the line is: delay_parameters 1 -1/-1 8000/8000 Note that the figure -1 is used to represent "unlimited". 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 256kbps (strict limit) with each 8-bit network permitted 64kbps (strict limit) and each individual host permitted 4800bps with a bucket maximum size of 64kb 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 There must be one delay_parameters line for each delay pool. DOC_END NAME: delay_initial_bucket_level COMMENT: (percent, 0-100) TYPE: ushort DEFAULT: 50 IFDEF: 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 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: wccp_router TYPE: address LOC: Config.Wccp.router DEFAULT: 0.0.0.0 IFDEF: USE_WCCP DOC_NONE NAME: wccp2_router TYPE: sockaddr_in_list LOC: Config.Wccp2.router DEFAULT: none 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: int LOC: Config.Wccp2.forwarding_method DEFAULT: 1 IFDEF: USE_WCCPv2 DOC_START WCCP2 allows the setting of forwarding methods between the router/switch and the cache. Valid values are as follows: 1 - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) 2 - 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: int LOC: Config.Wccp2.return_method DEFAULT: 1 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: 1 - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) 2 - 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: int LOC: Config.Wccp2.assignment_method DEFAULT: 1 IFDEF: USE_WCCPv2 DOC_START WCCP2 allows the setting of methods to assign the WCCP hash Valid values are as follows: 1 - Hash assignment 2 - 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: none DEFAULT_IF_NONE: standard 0 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 IFDEF: USE_WCCP DOC_NONE NAME: wccp2_address TYPE: address LOC: Config.Wccp2.address DEFAULT: 0.0.0.0 IFDEF: USE_WCCPv2 DOC_START Use this option if you require WCCP 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_NONE NAME: server_persistent_connections TYPE: onoff LOC: Config.onoff.server_pconns DEFAULT: on DOC_START Persistent connection support for clients and servers. By default, Squid uses persistent connections (when allowed) with its clients and servers. You can use these options to disable persistent connections with clients and/or servers. DOC_END NAME: persistent_connection_after_error TYPE: onoff LOC: Config.onoff.error_pconns DEFAULT: off 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. 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: ushort LOC: Config.Port.snmp DEFAULT: 3401 IFDEF: SQUID_SNMP DOC_START Squid can now serve statistics and status information via SNMP. By default it listens to port 3401 on the machine. If you don't wish to use SNMP, set this to "0". DOC_END NAME: snmp_access TYPE: acl_access LOC: Config.accessList.snmp DEFAULT: none DEFAULT_IF_NONE: deny all 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 ... Example: snmp_access allow snmppublic localhost snmp_access deny all DOC_END NAME: snmp_incoming_address TYPE: address LOC: Config.Addrs.snmp_incoming DEFAULT: 0.0.0.0 IFDEF: SQUID_SNMP DOC_NONE NAME: snmp_outgoing_address TYPE: address LOC: Config.Addrs.snmp_outgoing DEFAULT: 255.255.255.255 IFDEF: SQUID_SNMP DOC_START Just like 'udp_incoming_address' above, but for the SNMP port. snmp_incoming_address is used for the SNMP socket receiving messages from SNMP agents. snmp_outgoing_address is used for SNMP packets returned to SNMP agents. The default snmp_incoming_address (0.0.0.0) is to listen on all available network interfaces. If snmp_outgoing_address is set to 255.255.255.255 (the default) 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 port 3401. DOC_END COMMENT_START ICP OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: icp_port udp_port TYPE: ushort DEFAULT: @DEFAULT_ICP_PORT@ LOC: Config.Port.icp DOC_START The port number where Squid sends and receives ICP queries to and from neighbor caches. Default is 3130. To disable use "0". May be overridden with -u on the command line. DOC_END NAME: htcp_port IFDEF: USE_HTCP TYPE: ushort DEFAULT: 4827 LOC: Config.Port.htcp DOC_START The port number where Squid sends and receives HTCP queries to and from neighbor caches. Default is 4827. To disable use "0". 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: 0.0.0.0 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: 255.255.255.255 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 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_NONE NAME: netdb_high TYPE: int DEFAULT: 1000 LOC: Config.Netdb.high DOC_START The low and high water marks for the ICMP measurement database. These are counts, not percents. The defaults are 900 and 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 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 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: 255.255.255.255 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: ushort 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: ushort 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: off DOC_START If this is enabled Squid will use short URLs for icons. If off the URLs for icons will always be absolute URLs including the proxy name and port. DOC_END COMMENT_START ERROR PAGE OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: error_directory TYPE: string LOC: Config.errorDirectory DEFAULT: @DEFAULT_ERROR_DIR@ DOC_START If you wish to create your own versions of the default (English) error files, either to customize them to suit your language or company copy the template English files to another directory and point this tag at them. The squid developers are interested in making squid available in a wide variety of languages. If you are making translations for a langauge that Squid does not currently provide please consider contributing your translation back to the project. DOC_END NAME: error_map TYPE: errormap LOC: Config.errorMapList DEFAULT: none DOC_START Map errors to custom messages error_map message_url http_status ... http_status ... is a list of HTTP status codes or Squid error messages. Use in accelerators to substitute the error messages returned by servers with other custom errors. error_map http://your.server/error/404.shtml 404 Requests for error messages is a GET request for the configured URL with the following special headers X-Error-Status: The received HTTP status code (i.e. 404) X-Request-URI: The requested URI where the error occurred In Addition the following headers are forwarded from the client request: User-Agent, Cookie, X-Forwarded-For, Via, Authorization, Accept, Referer And the following headers from the server reply: Server, Via, Location, Content-Location The reply returned to the client will carry the original HTTP headers from the real error message, but with the reply body of the configured error message. 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: deny_info TYPE: denyinfo LOC: Config.denyInfoList DEFAULT: none DOC_START Usage: deny_info err_page_name acl or deny_info http://... acl Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys 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. You may use ERR_ pages that come with Squid or create your own pages and put them into the configured errors/ directory. Alternatively you can specify an error URL. The browsers will get redirected (302) to the specified URL. %s in the redirection URL will be replaced by the requested URL. Alternatively you can tell Squid to reset the TCP connection by specifying TCP_RESET. 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 (matching hierarchy_stoplist or not cacheable request type) direct to origin servers. If you set this 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. If you are inside an firewall see never_direct instead of this directive. 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: always_direct TYPE: acl_access LOC: Config.accessList.AlwaysDirect DEFAULT: none 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 no_cache. This option replaces some v1.1 options such as local_domain and local_ip. DOC_END NAME: never_direct TYPE: acl_access LOC: Config.accessList.NeverDirect DEFAULT: none 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 acl all src 0.0.0.0/0.0.0.0 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 option replaces some v1.1 options such as inside_firewall and firewall_ip. DOC_END COMMENT_START ADVANCED NETWORKING OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: incoming_icp_average TYPE: int DEFAULT: 6 LOC: Config.comm_incoming.icp_average DOC_NONE NAME: incoming_http_average TYPE: int DEFAULT: 4 LOC: Config.comm_incoming.http_average DOC_NONE NAME: incoming_dns_average TYPE: int DEFAULT: 4 LOC: Config.comm_incoming.dns_average DOC_NONE NAME: min_icp_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.icp_min_poll DOC_NONE NAME: min_dns_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.dns_min_poll DOC_NONE NAME: min_http_poll_cnt TYPE: int DEFAULT: 8 LOC: Config.comm_incoming.http_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: tcp_recv_bufsize COMMENT: (bytes) TYPE: b_size_t DEFAULT: 0 bytes LOC: Config.tcpRcvBufsz DOC_START Size of receive buffer to set for TCP sockets. Probably just as easy to change your kernel's default. Set to zero to use the default buffer size. DOC_END COMMENT_START DNS OPTIONS ----------------------------------------------------------------------------- COMMENT_END NAME: check_hostnames TYPE: onoff DEFAULT: on LOC: Config.onoff.check_hostnames DOC_START For security and stability reasons Squid by default checks hostnames for Internet standard RFC compliance. If you do not want Squid to perform these checks then turn this directive off. 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: cache_dns_program TYPE: string IFDEF: USE_DNSSERVERS DEFAULT: @DEFAULT_DNSSERVER@ LOC: Config.Program.dnsserver DOC_START Specify the location of the executable for dnslookup process. DOC_END NAME: dns_children TYPE: int IFDEF: USE_DNSSERVERS DEFAULT: 5 LOC: Config.dnsChildren DOC_START The number of processes spawn to service DNS name lookups. For heavily loaded caches on large servers, you should probably increase this value to at least 10. The maximum is 32. The default is 5. You must have at least one dnsserver process. DOC_END NAME: dns_retransmit_interval TYPE: time_t DEFAULT: 5 seconds LOC: Config.Timeout.idns_retransmit IFDEF: !USE_DNSSERVERS 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_t DEFAULT: 2 minutes LOC: Config.Timeout.idns_query IFDEF: !USE_DNSSERVERS 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_defnames COMMENT: on|off TYPE: onoff DEFAULT: off 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_nameservers TYPE: wordlist DEFAULT: none 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: dns_testnames TYPE: wordlist LOC: Config.dns_testname_list DEFAULT: none DEFAULT_IF_NONE: netscape.com internic.net nlanr.net microsoft.com DOC_START The DNS tests exit as soon as the first site is successfully looked up This test can be disabled with the -D command line option. DOC_END NAME: append_domain TYPE: string LOC: Config.appendDomain DEFAULT: none 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_NONE 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: 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_size_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 zero, 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. 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 TYPE: onoff DEFAULT: on LOC: opt_forwarded_for DOC_START If set, Squid will include your system's IP address or name in the HTTP requests it forwards. By default it looks like this: X-Forwarded-For: 192.1.2.3 If you disable this, it will appear as X-Forwarded-For: unknown DOC_END NAME: cachemgr_passwd TYPE: cachemgrpasswd DEFAULT: none 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 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: reload_into_ims IFDEF: 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: maximum_single_addr_tries TYPE: int LOC: Config.retry.maxtries DEFAULT: 1 DOC_START This sets the maximum number of connection attempts for a host that only has one address (for multiple-address hosts, each address is tried once). The default value is one attempt, the (not recommended) maximum is 255 tries. A warning message will be generated if it is set to a value greater than ten. Note: This is in addition to the request re-forwarding which takes place if Squid fails to get a satisfying response. 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. This is mainly useful if you are in a complex cache hierarchy to work around access control errors. DOC_END NAME: as_whois_server TYPE: string LOC: Config.as_whois_server DEFAULT: whois.ra.net DEFAULT_IF_NONE: 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. deny: The request is denied. The user receives an "Invalid Request" message. 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. encode: The request is allowed and the whitespace characters are encoded according to RFC1738. This could be considered a violation of the HTTP/1.1 RFC because proxies are not allowed to rewrite URI's. chop: The request is allowed and the URI is chopped at the first whitespace. This might also be considered a violation. DOC_END NAME: coredump_dir TYPE: string LOC: Config.coredump_dir DEFAULT: none DEFAULT_IF_NONE: none 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 NAME: chroot TYPE: string LOC: Config.chroot_dir DEFAULT: none DOC_START Use this to have Squid 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 will may get an error saying that Squid can not open the port. DOC_END NAME: balance_on_multiple_ip TYPE: onoff LOC: Config.onoff.balance_on_multiple_ip DEFAULT: on DOC_START Some load balancing servers based on round robin DNS have been found not to preserve user session state across requests to different IP addresses. By default Squid rotates IP's per request. By disabling this directive only connection failure triggers rotation. DOC_END NAME: pipeline_prefetch TYPE: onoff LOC: Config.onoff.pipeline_prefetch DEFAULT: off DOC_START To boost the performance of pipelined requests to closer match that of a non-proxied environment Squid can try to fetch up to two requests in parallel from a pipeline. Defaults to off for bandwidth management and access logging reasons. DOC_END NAME: high_response_time_warning TYPE: int COMMENT: (msec) LOC: Config.warnings.high_rptm DEFAULT: 0 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 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 DEFAULT: 0 KB DOC_START If the memory usage (as determined by mallinfo) exceeds this amount, Squid prints a WARNING with debug level 0 to get the administrators attention. DOC_END 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 EOF .