char *cksshv = "SSH support, 8.0.001, 13 Sep 2000"; /* C K _ S S H . C -- OpenSSL Interface for C-Kermit Copyright (C) 1985, 2001, Trustees of Columbia University in the City of New York. All rights reserved. See the C-Kermit COPYING.TXT file or the copyright text in the ckcmai.c module for disclaimer and permissions. Copyright (c) 1995 Tatu Ylonen , Espoo, Finland All rights reserved Includes work by Niels Provos to work with OpenSSL. */ #include "ckcdeb.h" #ifdef SSH #undef SSH #endif /* SSH */ #ifdef CK_SSL #ifdef SSH #include #include #include #include #include #include #include #include #include #ifdef OS2 #include "ckossl.h" #endif /* OS2 */ static char *client_version_string = NULL; static char *server_version_string = NULL; /* Flag indicating whether IPv4 or IPv6. This should be a SET TCP ... command. Need to look at supporting IPv6 in ckcnet.c. AF_UNSPEC means both IPv4 and IPv6. */ static int IPv4or6 = AF_INET; /* Flag indicating whether debug mode is on. SET SSH DEBUG {ON, OFF } */ static int debug_flag = 0; /* Flag indicating whether a tty should be allocated */ /* In other words, was Kermit started from a tty? */ static int tty_flag = 0; /* don't exec a shell */ static int no_shell_flag = 0; static int no_tty_flag = 0; /* * Flag indicating that nothing should be read from stdin. * Not sure we should support this in Kermit */ static int stdin_null_flag = 0; /* * Flag indicating that ssh should fork after authentication. This is useful * so that the pasphrase can be entered manually, and then ssh goes to the * background. We will not support this in Kermit. */ static int fork_after_authentication_flag = 0; /* * General data structure for command line options and options configurable * in configuration files. */ #define SSH_MAX_IDENTITY_FILES 100 #define SSH_MAX_FORWARDS_PER_DIRECTION 100 /* Data structure for representing a forwarding request. */ typedef struct { u_short port; /* Port to forward. */ char *host; /* Host to connect. */ u_short host_port; /* Port to connect on host. */ } Forward; /* Data structure for representing option data. */ typedef enum { SYSLOG_LEVEL_QUIET, SYSLOG_LEVEL_FATAL, SYSLOG_LEVEL_ERROR, SYSLOG_LEVEL_INFO, SYSLOG_LEVEL_VERBOSE, SYSLOG_LEVEL_DEBUG } LogLevel; typedef struct { int forward_agent; /* Forward authentication agent. */ int forward_x11; /* Forward X11 display. */ char *xauth_location; /* Location for xauth program */ int gateway_ports; /* Allow remote connects to forwarded ports. */ int use_privileged_port; /* Don't use privileged port if false. * int rhosts_authentication; /* Try rhosts authentication. */ int rhosts_rsa_authentication; /* Try rhosts with RSA * authentication. */ int rsa_authentication; /* Try RSA authentication. */ int dsa_authentication; /* Try DSA authentication. */ int skey_authentication; /* Try S/Key or TIS authentication. */ #ifdef KRB4 int kerberos_authentication; /* Try Kerberos * authentication. */ #endif #ifdef AFS int kerberos_tgt_passing; /* Try Kerberos tgt passing. */ int afs_token_passing; /* Try AFS token passing. */ #endif int password_authentication; /* Try password * authentication. */ int fallback_to_rsh;/* Use rsh if cannot connect with ssh. */ int use_rsh; /* Always use rsh (don\'t try ssh). */ int batch_mode; /* Batch mode: do not ask for passwords. */ int check_host_ip; /* Also keep track of keys for IP address */ int strict_host_key_checking; /* Strict host key checking. */ int compression; /* Compress packets in both directions. */ int compression_level; /* Compression level 1 (fast) to 9 * (best). */ int keepalives; /* Set SO_KEEPALIVE. */ LogLevel log_level; /* Level for logging. */ int port; /* Port to connect. */ int connection_attempts; /* Max attempts (seconds) before * giving up */ int number_of_password_prompts; /* Max number of password * prompts. */ int cipher; /* Cipher to use. */ char *ciphers; /* SSH2 ciphers in order of preference. */ int protocol; /* Protocol in order of preference. */ char *hostname; /* Real host to connect. */ char *proxy_command; /* Proxy command for connecting the host. */ char *user; /* User to log in as. */ int escape_char; /* Escape character; -2 = none */ char *system_hostfile;/* Path for /etc/ssh_known_hosts. */ char *user_hostfile; /* Path for $HOME/.ssh/known_hosts. */ char *system_hostfile2; char *user_hostfile2; int num_identity_files; /* Number of files for RSA identities. * int num_identity_files2; /* DSA identities. */ char *identity_files[SSH_MAX_IDENTITY_FILES]; char *identity_files2[SSH_MAX_IDENTITY_FILES]; /* Local TCP/IP forward requests. */ int num_local_forwards; Forward local_forwards[SSH_MAX_FORWARDS_PER_DIRECTION]; /* Remote TCP/IP forward requests. */ int num_remote_forwards; Forward remote_forwards[SSH_MAX_FORWARDS_PER_DIRECTION]; } Options; static Options options; /* * Name of the host we are connecting to. This is the name given on the * command line, or the HostName specified for the user-supplied name in a * configuration file. */ static char *host; /* socket address the host resolves to */ static struct sockaddr_storage hostaddr; /* * Flag to indicate that we have received a window change signal which has * not yet been processed. This will cause a message indicating the new * window size to be sent to the server a little later. This is volatile * because this is updated in a signal handler. */ static volatile int received_window_change_signal = 0; /* Value of argv[0] (set in the main program). */ static char *av0; /* Flag indicating whether we have a valid host private key loaded. */ static int host_private_key_loaded = 0; /* Host private key. */ static RSA *host_private_key = NULL; /* Original real UID. */ static uid_t original_real_uid; /* command to be executed */ static Buffer command; /* SSH command line usage. Use this to design the Kermit "ssh" personality. */ /* fprintf(stderr, "Usage: %s [options] host [command]\n", av0); fprintf(stderr, "Options:\n"); fprintf(stderr, " -l user Log in using this user name.\n"); fprintf(stderr, " -n Redirect input from /dev/null.\n"); fprintf(stderr, " -A Enable authentication agent forwarding.\n"); fprintf(stderr, " -a Disable authentication agent forwarding.\n"); #ifdef AFS fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); #endif /* AFS */ fprintf(stderr, " -X Enable X11 connection forwarding.\n"); fprintf(stderr, " -x Disable X11 connection forwarding.\n"); fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); fprintf(stderr, " -T Do not allocate a tty.\n"); fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); fprintf(stderr, " -V Display version number only.\n"); fprintf(stderr, " -P Don't allocate a privileged port.\n"); fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); fprintf(stderr, " -f Fork into background after authentication.\n"); fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); fprintf(stderr, " -c cipher Select encryption algorithm: " "``3des'', " "``blowfish''\n"); fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); fprintf(stderr, " -C Enable compression.\n"); fprintf(stderr, " -N Do not execute a shell or command.\n"); fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); fprintf(stderr, " -4 Use IPv4 only.\n"); fprintf(stderr, " -6 Use IPv6 only.\n"); fprintf(stderr, " -2 Force protocol version 2.\n"); fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); */ /* Function prototypes */ _PROTOTYP(static int ssh_session,(void)); _PROTOTYP(static int ssh_session2,(void)); _PROTOTYP(VOID client_set_session_ident,(int id)); /* * Connects to the given host using rsh (or prints an error message and exits * if rsh is not available). This function never returns. */ static void rsh_connect(char *host, char *user, Buffer * command) { char *args[10]; int i; log("Using rsh. WARNING: Connection will not be encrypted."); /* Build argument list for rsh. */ i = 0; args[i++] = _PATH_RSH; /* host may have to come after user on some systems */ args[i++] = host; if (user) { args[i++] = "-l"; args[i++] = user; } if (buffer_len(command) > 0) { buffer_append(command, "\0", 1); args[i++] = buffer_ptr(command); } args[i++] = NULL; if (debug_flag) { for (i = 0; args[i]; i++) { if (i != 0) fprintf(stderr, " "); fprintf(stderr, "%s", args[i]); } fprintf(stderr, "\n"); } execv(_PATH_RSH, args); perror(_PATH_RSH); exit(1); } /* * Main program for the ssh client. */ static int main(int ac, char **av) { int i, opt, optind, exit_status, ok; u_short fwd_port, fwd_host_port; char *optarg, *cp, buf[256]; struct stat st; struct passwd *pw, pwcopy; int dummy; uid_t original_effective_uid; init_rng(); /* * Save the original real uid. It will be needed later (uid-swapping * may clobber the real uid). */ original_real_uid = getuid(); original_effective_uid = geteuid(); /* If we are installed setuid root be careful to not drop core. */ if (original_real_uid != original_effective_uid) { struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = 0; if (setrlimit(RLIMIT_CORE, &rlim) < 0) fatal("setrlimit failed: %.100s", strerror(errno)); } /* * Use uid-swapping to give up root privileges for the duration of * option processing. We will re-instantiate the rights when we are * ready to create the privileged port, and will permanently drop * them when the port has been created (actually, when the connection * has been made, as we may need to create the port several times). */ temporarily_use_uid(original_real_uid); /* * Set our umask to something reasonable, as some files are created * with the default umask. This will make them world-readable but * writable only by the owner, which is ok for all files for which we * don't set the modes explicitly. */ umask(022); /* Save our own name. */ av0 = av[0]; /* Initialize option structure to indicate that no values have been set. */ initialize_options(&options); /* Parse command-line arguments. */ host = NULL; /* If program name is not one of the standard names, use it as host name. */ if (strchr(av0, '/')) cp = strrchr(av0, '/') + 1; else cp = av0; if (strcmp(cp, "rsh") && strcmp(cp, "ssh") && strcmp(cp, "rlogin") && strcmp(cp, "slogin") && strcmp(cp, "remsh")) host = cp; for (optind = 1; optind < ac; optind++) { if (av[optind][0] != '-') { if (host) break; if ((cp = strchr(av[optind], '@'))) { if(cp == av[optind]) usage(); options.user = av[optind]; *cp = '\0'; host = ++cp; } else host = av[optind]; continue; } opt = av[optind][1]; if (!opt) usage(); if (strchr("eilcpLRo", opt)) { /* options with arguments */ optarg = av[optind] + 2; if (strcmp(optarg, "") == 0) { if (optind >= ac - 1) usage(); optarg = av[++optind]; } } else { if (av[optind][2]) usage(); optarg = NULL; } switch (opt) { case '2': options.protocol = SSH_PROTO_2; break; case '4': IPv4or6 = AF_INET; break; case '6': IPv4or6 = AF_INET6; break; case 'n': stdin_null_flag = 1; break; case 'f': fork_after_authentication_flag = 1; stdin_null_flag = 1; break; case 'x': options.forward_x11 = 0; break; case 'X': options.forward_x11 = 1; break; case 'g': options.gateway_ports = 1; break; case 'P': options.use_privileged_port = 0; break; case 'a': options.forward_agent = 0; break; case 'A': options.forward_agent = 1; break; #ifdef AFS case 'k': options.kerberos_tgt_passing = 0; options.afs_token_passing = 0; break; #endif case 'i': if (stat(optarg, &st) < 0) { fprintf(stderr, "Warning: Identity file %s does not exist.\n", optarg); break; } if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) fatal("Too many identity files specified (max %d)", SSH_MAX_IDENTITY_FILES); options.identity_files[options.num_identity_files++] = xstrdup(optarg); break; case 't': tty_flag = 1; break; case 'v': case 'V': fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n", SSH_VERSION, PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2); fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay()); if (opt == 'V') exit(0); debug_flag = 1; options.log_level = SYSLOG_LEVEL_DEBUG; break; case 'q': options.log_level = SYSLOG_LEVEL_QUIET; break; case 'e': if (optarg[0] == '^' && optarg[2] == 0 && (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) options.escape_char = (unsigned char) optarg[1] & 31; else if (strlen(optarg) == 1) options.escape_char = (unsigned char) optarg[0]; else if (strcmp(optarg, "none") == 0) options.escape_char = -2; else { fprintf(stderr, "Bad escape character '%s'.\n", optarg); exit(1); } break; case 'c': if (ciphers_valid(optarg)) { /* SSH2 only */ options.ciphers = xstrdup(optarg); options.cipher = SSH_CIPHER_ILLEGAL; } else { /* SSH1 only */ options.cipher = cipher_number(optarg); if (options.cipher == -1) { fprintf(stderr, "Unknown cipher type '%s'\n", optarg); exit(1); } } break; case 'p': options.port = atoi(optarg); break; case 'l': options.user = optarg; break; case 'R': if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, &fwd_host_port) != 3 && sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, &fwd_host_port) != 3) { fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); usage(); /* NOTREACHED */ } add_remote_forward(&options, fwd_port, buf, fwd_host_port); break; case 'L': if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, &fwd_host_port) != 3 && sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, &fwd_host_port) != 3) { fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); usage(); /* NOTREACHED */ } add_local_forward(&options, fwd_port, buf, fwd_host_port); break; case 'C': options.compression = 1; break; case 'N': no_shell_flag = 1; no_tty_flag = 1; break; case 'T': no_tty_flag = 1; break; case 'o': dummy = 1; if (process_config_line(&options, host ? host : "", optarg, "command-line", 0, &dummy) != 0) exit(1); break; default: usage(); } } /* Check that we got a host name. */ if (!host) usage(); /* Initialize the command to execute on remote host. */ buffer_init(&command); SSLeay_add_all_algorithms(); /* * Save the command to execute on the remote host in a buffer. There * is no limit on the length of the command, except by the maximum * packet size. Also sets the tty flag if there is no command. */ if (optind == ac) { /* No command specified - execute shell on a tty. */ tty_flag = 1; } else { /* A command has been specified. Store it into the buffer. */ for (i = optind; i < ac; i++) { if (i > optind) buffer_append(&command, " ", 1); buffer_append(&command, av[i], strlen(av[i])); } } /* Cannot fork to background if no command. */ if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) fatal("Cannot fork into background without a command to execute."); /* Allocate a tty by default if no command specified. */ if (buffer_len(&command) == 0) tty_flag = 1; /* Do not allocate a tty if stdin is not a tty. */ if (!isatty(fileno(stdin))) { if (tty_flag) fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); tty_flag = 0; } /* force */ if (no_tty_flag) tty_flag = 0; /* Get user data. */ pw = getpwuid(original_real_uid); if (!pw) { fprintf(stderr, "You don't exist, go away!\n"); exit(1); } /* Take a copy of the returned structure. */ memset(&pwcopy, 0, sizeof(pwcopy)); pwcopy.pw_name = xstrdup(pw->pw_name); pwcopy.pw_passwd = xstrdup(pw->pw_passwd); pwcopy.pw_uid = pw->pw_uid; pwcopy.pw_gid = pw->pw_gid; #ifdef HAVE_PW_CLASS_IN_PASSWD pwcopy.pw_class = xstrdup(pw->pw_class); #endif pwcopy.pw_dir = xstrdup(pw->pw_dir); pwcopy.pw_shell = xstrdup(pw->pw_shell); pw = &pwcopy; /* Initialize "log" output. Since we are the client all output actually goes to the terminal. */ log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); /* Read per-user configuration file. */ snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); read_config_file(buf, host, &options); /* Read systemwide configuration file. */ read_config_file(HOST_CONFIG_FILE, host, &options); /* Fill configuration defaults. */ fill_default_options(&options); /* reinit */ log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); /* check if RSA support exists */ if ((options.protocol & SSH_PROTO_1) && rsa_alive() == 0) { log("%s: no RSA support in libssl and libcrypto. See ssl(8).", __progname); log("Disabling protocol version 1"); options.protocol &= ~ (SSH_PROTO_1|SSH_PROTO_1_PREFERRED); } if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { fprintf(stderr, "%s: No protocol version available.\n", __progname); exit(1); } if (options.user == NULL) options.user = xstrdup(pw->pw_name); if (options.hostname != NULL) host = options.hostname; /* Find canonic host name. */ if (strchr(host, '.') == 0) { struct addrinfo hints; struct addrinfo *ai = NULL; int errgai; memset(&hints, 0, sizeof(hints)); hints.ai_family = IPv4or6; hints.ai_flags = AI_CANONNAME; hints.ai_socktype = SOCK_STREAM; errgai = getaddrinfo(host, NULL, &hints, &ai); if (errgai == 0) { if (ai->ai_canonname != NULL) host = xstrdup(ai->ai_canonname); freeaddrinfo(ai); } } /* Disable rhosts authentication if not running as root. */ if (original_effective_uid != 0 || !options.use_privileged_port) { options.rhosts_authentication = 0; options.rhosts_rsa_authentication = 0; } /* * If using rsh has been selected, exec it now (without trying * anything else). Note that we must release privileges first. */ if (options.use_rsh) { /* * Restore our superuser privileges. This must be done * before permanently setting the uid. */ restore_uid(); /* Switch to the original uid permanently. */ permanently_set_uid(original_real_uid); /* Execute rsh. */ rsh_connect(host, options.user, &command); fatal("rsh_connect returned"); } /* Restore our superuser privileges. */ restore_uid(); /* * Open a connection to the remote host. This needs root privileges * if rhosts_{rsa_}authentication is enabled. */ ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts, !options.rhosts_authentication && !options.rhosts_rsa_authentication, original_real_uid, options.proxy_command); /* * If we successfully made the connection, load the host private key * in case we will need it later for combined rsa-rhosts * authentication. This must be done before releasing extra * privileges, because the file is only readable by root. */ if (ok && (options.protocol & SSH_PROTO_1)) { Key k; host_private_key = RSA_new(); k.type = KEY_RSA; k.rsa = host_private_key; if (load_private_key(HOST_KEY_FILE, "", &k, NULL)) host_private_key_loaded = 1; } /* * Get rid of any extra privileges that we may have. We will no * longer need them. Also, extra privileges could make it very hard * to read identity files and other non-world-readable files from the * user's home directory if it happens to be on a NFS volume where * root is mapped to nobody. */ /* * Note that some legacy systems need to postpone the following call * to permanently_set_uid() until the private hostkey is destroyed * with RSA_free(). Otherwise the calling user could ptrace() the * process, read the private hostkey and impersonate the host. * OpenBSD does not allow ptracing of setuid processes. */ permanently_set_uid(original_real_uid); /* * Now that we are back to our own permissions, create ~/.ssh * directory if it doesn\'t already exist. */ snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); if (stat(buf, &st) < 0) if (mkdir(buf, 0700) < 0) error("Could not create directory '%.200s'.", buf); /* Check if the connection failed, and try "rsh" if appropriate. */ if (!ok) { if (options.port != 0) log("Secure connection to %.100s on port %hu refused%.100s.", host, options.port, options.fallback_to_rsh ? "; reverting to insecure method" : ""); else log("Secure connection to %.100s refused%.100s.", host, options.fallback_to_rsh ? "; reverting to insecure method" : ""); if (options.fallback_to_rsh) { rsh_connect(host, options.user, &command); fatal("rsh_connect returned"); } exit(1); } /* Expand ~ in options.identity_files. */ /* XXX mem-leaks */ for (i = 0; i < options.num_identity_files; i++) options.identity_files[i] = tilde_expand_filename(options.identity_files[i], original_real_uid); for (i = 0; i < options.num_identity_files2; i++) options.identity_files2[i] = tilde_expand_filename(options.identity_files2[i], original_real_uid); /* Expand ~ in known host file names. */ options.system_hostfile = tilde_expand_filename(options.system_hostfile, original_real_uid); options.user_hostfile = tilde_expand_filename(options.user_hostfile, original_real_uid); options.system_hostfile2 = tilde_expand_filename(options.system_hostfile2, original_real_uid); options.user_hostfile2 = tilde_expand_filename(options.user_hostfile2, original_real_uid); /* Log into the remote system. This never returns if the login fails. */ ssh_login(host_private_key_loaded, host_private_key, host, (struct sockaddr *)&hostaddr, original_real_uid); /* We no longer need the host private key. Clear it now. */ if (host_private_key_loaded) RSA_free(host_private_key); /* Destroys contents safely */ exit_status = compat20 ? ssh_session2() : ssh_session(); packet_close(); return exit_status; } static void x11_get_proto(char *proto, int proto_len, char *data, int data_len) { char line[512]; FILE *f; int got_data = 0, i; if (options.xauth_location) { /* Try to get Xauthority information for the display. */ snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", options.xauth_location, getenv("DISPLAY")); f = popen(line, "r"); if (f && fgets(line, sizeof(line), f) && sscanf(line, "%*s %s %s", proto, data) == 2) got_data = 1; if (f) pclose(f); } /* * If we didn't get authentication data, just make up some * data. The forwarding code will check the validity of the * response anyway, and substitute this data. The X11 * server, however, will ignore this fake data and use * whatever authentication mechanisms it was using otherwise * for the local connection. */ if (!got_data) { u_int32_t rand = 0; strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); for (i = 0; i < 16; i++) { if (i % 4 == 0) rand = arc4random(); snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); rand >>= 8; } } } static int ssh_session(void) { int type; int i; int plen; int interactive = 0; int have_tty = 0; struct winsize ws; int authfd; char *cp; /* Enable compression if requested. */ if (options.compression) { debug("Requesting compression at level %d.", options.compression_level); if (options.compression_level < 1 || options.compression_level > 9) fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); /* Send the request. */ packet_start(SSH_CMSG_REQUEST_COMPRESSION); packet_put_int(options.compression_level); packet_send(); packet_write_wait(); type = packet_read(&plen); if (type == SSH_SMSG_SUCCESS) packet_start_compression(options.compression_level); else if (type == SSH_SMSG_FAILURE) log("Warning: Remote host refused compression."); else packet_disconnect("Protocol error waiting for compression response."); } /* Allocate a pseudo tty if appropriate. */ if (tty_flag) { debug("Requesting pty."); /* Start the packet. */ packet_start(SSH_CMSG_REQUEST_PTY); /* Store TERM in the packet. There is no limit on the length of the string. */ cp = getenv("TERM"); if (!cp) cp = ""; packet_put_string(cp, strlen(cp)); /* Store window size in the packet. */ if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) memset(&ws, 0, sizeof(ws)); packet_put_int(ws.ws_row); packet_put_int(ws.ws_col); packet_put_int(ws.ws_xpixel); packet_put_int(ws.ws_ypixel); /* Store tty modes in the packet. */ tty_make_modes(fileno(stdin)); /* Send the packet, and wait for it to leave. */ packet_send(); packet_write_wait(); /* Read response from the server. */ type = packet_read(&plen); if (type == SSH_SMSG_SUCCESS) { interactive = 1; have_tty = 1; } else if (type == SSH_SMSG_FAILURE) log("Warning: Remote host failed or refused to allocate a pseudo tty."); else packet_disconnect("Protocol error waiting for pty request response."); } /* Request X11 forwarding if enabled and DISPLAY is set. */ if (options.forward_x11 && getenv("DISPLAY") != NULL) { char proto[512], data[512]; /* Get reasonable local authentication information. */ x11_get_proto(proto, sizeof proto, data, sizeof data); /* Request forwarding with authentication spoofing. */ debug("Requesting X11 forwarding with authentication spoofing."); x11_request_forwarding_with_spoofing(0, proto, data); /* Read response from the server. */ type = packet_read(&plen); if (type == SSH_SMSG_SUCCESS) { interactive = 1; } else if (type == SSH_SMSG_FAILURE) { log("Warning: Remote host denied X11 forwarding."); } else { packet_disconnect("Protocol error waiting for X11 forwarding"); } } /* Tell the packet module whether this is an interactive session. */ packet_set_interactive(interactive, options.keepalives); /* Clear agent forwarding if we don\'t have an agent. */ authfd = ssh_get_authentication_socket(); if (authfd < 0) options.forward_agent = 0; else ssh_close_authentication_socket(authfd); /* Request authentication agent forwarding if appropriate. */ if (options.forward_agent) { debug("Requesting authentication agent forwarding."); auth_request_forwarding(); /* Read response from the server. */ type = packet_read(&plen); packet_integrity_check(plen, 0, type); if (type != SSH_SMSG_SUCCESS) log("Warning: Remote host denied authentication agent forwarding."); } /* Initiate local TCP/IP port forwardings. */ for (i = 0; i < options.num_local_forwards; i++) { debug("Connections to local port %d forwarded to remote address %.200s:%d", options.local_forwards[i].port, options.local_forwards[i].host, options.local_forwards[i].host_port); channel_request_local_forwarding(options.local_forwards[i].port, options.local_forwards[i].host, options.local_forwards[i].host_port, options.gateway_ports); } /* Initiate remote TCP/IP port forwardings. */ for (i = 0; i < options.num_remote_forwards; i++) { debug("Connections to remote port %d forwarded to local address %.200s:%d", options.remote_forwards[i].port, options.remote_forwards[i].host, options.remote_forwards[i].host_port); channel_request_remote_forwarding(options.remote_forwards[i].port, options.remote_forwards[i].host, options.remote_forwards[i].host_port); } /* If requested, let ssh continue in the background. */ if (fork_after_authentication_flag) if (daemon(1, 1) < 0) fatal("daemon() failed: %.200s", strerror(errno)); /* * If a command was specified on the command line, execute the * command now. Otherwise request the server to start a shell. */ if (buffer_len(&command) > 0) { int len = buffer_len(&command); if (len > 900) len = 900; debug("Sending command: %.*s", len, buffer_ptr(&command)); packet_start(SSH_CMSG_EXEC_CMD); packet_put_string(buffer_ptr(&command), buffer_len(&command)); packet_send(); packet_write_wait(); } else { debug("Requesting shell."); packet_start(SSH_CMSG_EXEC_SHELL); packet_send(); packet_write_wait(); } /* Enter the interactive session. */ return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0); } static void init_local_fwd(void) { int i; /* Initiate local TCP/IP port forwardings. */ for (i = 0; i < options.num_local_forwards; i++) { debug("Connections to local port %d forwarded to remote address %.200s:%d", options.local_forwards[i].port, options.local_forwards[i].host, options.local_forwards[i].host_port); channel_request_local_forwarding(options.local_forwards[i].port, options.local_forwards[i].host, options.local_forwards[i].host_port, options.gateway_ports); } } static void client_init(int id, void *arg) { int len; debug("client_init id %d arg %d", id, (int)arg); if (no_shell_flag) goto done; if (tty_flag) { struct winsize ws; char *cp; cp = getenv("TERM"); if (!cp) cp = ""; /* Store window size in the packet. */ if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) memset(&ws, 0, sizeof(ws)); channel_request_start(id, "pty-req", 0); packet_put_cstring(cp); packet_put_int(ws.ws_col); packet_put_int(ws.ws_row); packet_put_int(ws.ws_xpixel); packet_put_int(ws.ws_ypixel); packet_put_cstring(""); /* XXX: encode terminal modes */ packet_send(); /* XXX wait for reply */ } if (options.forward_x11 && getenv("DISPLAY") != NULL) { char proto[512], data[512]; /* Get reasonable local authentication information. */ x11_get_proto(proto, sizeof proto, data, sizeof data); /* Request forwarding with authentication spoofing. */ debug("Requesting X11 forwarding with authentication spoofing."); x11_request_forwarding_with_spoofing(id, proto, data); /* XXX wait for reply */ } len = buffer_len(&command); if (len > 0) { if (len > 900) len = 900; debug("Sending command: %.*s", len, buffer_ptr(&command)); channel_request_start(id, "exec", 0); packet_put_string(buffer_ptr(&command), len); packet_send(); } else { channel_request(id, "shell", 0); } /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ done: /* register different callback, etc. XXX */ client_set_session_ident(id); } static int ssh_session2(void) { int window, packetmax, id; int in, out, err; if (stdin_null_flag) { in = open("/dev/null", O_RDONLY); } else { in = dup(STDIN_FILENO); } out = dup(STDOUT_FILENO); err = dup(STDERR_FILENO); if (in < 0 || out < 0 || err < 0) fatal("dup() in/out/err failed"); /* should be pre-session */ init_local_fwd(); /* If requested, let ssh continue in the background. */ if (fork_after_authentication_flag) if (daemon(1, 1) < 0) fatal("daemon() failed: %.200s", strerror(errno)); window = 32*1024; if (tty_flag) { packetmax = window/8; } else { window *= 2; packetmax = window/2; } /*XXX MAXPACK */ id = channel_new( "session", SSH_CHANNEL_OPENING, in, out, err, window, packetmax, CHAN_EXTENDED_WRITE, xstrdup("client-session")); channel_open(id); channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, client_init, (void *)0); return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id); } /* * Connect to the given ssh server using a proxy command. */ static int ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, const char *proxy_command) { Buffer command; const char *cp; char *command_string; int pin[2], pout[2]; pid_t pid; char strport[NI_MAXSERV]; /* Convert the port number into a string. */ snprintf(strport, sizeof strport, "%hu", port); /* Build the final command string in the buffer by making the appropriate substitutions to the given proxy command. */ buffer_init(&command); for (cp = proxy_command; *cp; cp++) { if (cp[0] == '%' && cp[1] == '%') { buffer_append(&command, "%", 1); cp++; continue; } if (cp[0] == '%' && cp[1] == 'h') { buffer_append(&command, host, strlen(host)); cp++; continue; } if (cp[0] == '%' && cp[1] == 'p') { buffer_append(&command, strport, strlen(strport)); cp++; continue; } buffer_append(&command, cp, 1); } buffer_append(&command, "\0", 1); /* Get the final command string. */ command_string = buffer_ptr(&command); /* Create pipes for communicating with the proxy. */ if (pipe(pin) < 0 || pipe(pout) < 0) fatal("Could not create pipes to communicate with the proxy: %.100s", strerror(errno)); debug("Executing proxy command: %.500s", command_string); /* Fork and execute the proxy command. */ if ((pid = fork()) == 0) { char *argv[10]; /* Child. Permanently give up superuser privileges. */ permanently_set_uid(original_real_uid); /* Redirect stdin and stdout. */ close(pin[1]); if (pin[0] != 0) { if (dup2(pin[0], 0) < 0) perror("dup2 stdin"); close(pin[0]); } close(pout[0]); if (dup2(pout[1], 1) < 0) perror("dup2 stdout"); /* Cannot be 1 because pin allocated two descriptors. */ close(pout[1]); /* Stderr is left as it is so that error messages get printed on the user's terminal. */ argv[0] = _PATH_BSHELL; argv[1] = "-c"; argv[2] = command_string; argv[3] = NULL; /* Execute the proxy command. Note that we gave up any extra privileges above. */ execv(_PATH_BSHELL, argv); perror(_PATH_BSHELL); exit(1); } /* Parent. */ if (pid < 0) fatal("fork failed: %.100s", strerror(errno)); /* Close child side of the descriptors. */ close(pin[0]); close(pout[1]); /* Free the command name. */ buffer_free(&command); /* Set the connection file descriptors. */ packet_set_connection(pout[0], pin[1]); return 1; } /* * Creates a (possibly privileged) socket for use as the ssh connection. */ static int ssh_create_socket(uid_t original_real_uid, int privileged, int family) { int sock; /* * If we are running as root and want to connect to a privileged * port, bind our own socket to a privileged port. */ if (privileged) { int p = IPPORT_RESERVED - 1; sock = rresvport_af(&p, family); if (sock < 0) error("rresvport: af=%d %.100s", family, strerror(errno)); else debug("Allocated local port %d.", p); } else { /* * Just create an ordinary socket on arbitrary port. We use * the user's uid to create the socket. */ temporarily_use_uid(original_real_uid); sock = socket(family, SOCK_STREAM, 0); if (sock < 0) error("socket: %.100s", strerror(errno)); restore_uid(); } return sock; } /* * Opens a TCP/IP connection to the remote server on the given host. * The address of the remote host will be returned in hostaddr. * If port is 0, the default port will be used. If anonymous is zero, * a privileged port will be allocated to make the connection. * This requires super-user privileges if anonymous is false. * Connection_attempts specifies the maximum number of tries (one per * second). If proxy_command is non-NULL, it specifies the command (with %h * and %p substituted for host and port, respectively) to use to contact * the daemon. */ static int ssh_connect(const char *host, struct sockaddr_storage * hostaddr, u_short port, int connection_attempts, int anonymous, uid_t original_real_uid, const char *proxy_command) { int sock = -1, attempt; struct servent *sp; struct addrinfo hints, *ai, *aitop; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; int gaierr; struct linger linger; debug("ssh_connect: getuid %u geteuid %u anon %d", (u_int) getuid(), (u_int) geteuid(), anonymous); /* Get default port if port has not been set. */ if (port == 0) { sp = getservbyname(SSH_SERVICE_NAME, "tcp"); if (sp) port = ntohs(sp->s_port); else port = SSH_DEFAULT_PORT; } /* If a proxy command is given, connect using it. */ if (proxy_command != NULL) return ssh_proxy_connect(host, port, original_real_uid, proxy_command); /* No proxy command. */ memset(&hints, 0, sizeof(hints)); hints.ai_family = IPv4or6; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%d", port); if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) fatal("%s: %.100s: %s", __progname, host, gai_strerror(gaierr)); /* * Try to connect several times. On some machines, the first time * will sometimes fail. In general socket code appears to behave * quite magically on many machines. */ for (attempt = 0; attempt < connection_attempts; attempt++) { if (attempt > 0) debug("Trying again..."); /* Loop through addresses for this host, and try each one in sequence until the connection succeeds. */ for (ai = aitop; ai; ai = ai->ai_next) { if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) continue; if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) { error("ssh_connect: getnameinfo failed"); continue; } debug("Connecting to %.200s [%.100s] port %s.", host, ntop, strport); /* Create a socket for connecting. */ sock = ssh_create_socket(original_real_uid, !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, ai->ai_family); if (sock < 0) continue; /* Connect to the host. We use the user's uid in the * hope that it will help with tcp_wrappers showing * the remote uid as root. */ temporarily_use_uid(original_real_uid); if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { /* Successful connection. */ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); restore_uid(); break; } else { debug("connect: %.100s", strerror(errno)); restore_uid(); /* * Close the failed socket; there appear to * be some problems when reusing a socket for * which connect() has already returned an * error. */ shutdown(sock, SHUT_RDWR); close(sock); } } if (ai) break; /* Successful connection. */ /* Sleep a moment before retrying. */ sleep(1); } freeaddrinfo(aitop); /* Return failure if we didn't get a successful connection. */ if (attempt >= connection_attempts) return 0; debug("Connection established."); /* * Set socket options. We would like the socket to disappear as soon * as it has been closed for whatever reason. */ /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ linger.l_onoff = 1; linger.l_linger = 5; setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); /* Set the connection. */ packet_set_connection(sock, sock); return 1; } /* * Waits for the server identification string, and sends our own * identification string. */ static void ssh_exchange_identification() { char buf[256], remote_version[256]; /* must be same size! */ int remote_major, remote_minor, i, mismatch; int connection_in = packet_get_connection_in(); int connection_out = packet_get_connection_out(); /* Read other side\'s version identification. */ for (;;) { for (i = 0; i < sizeof(buf) - 1; i++) { int len = atomicio(read, connection_in, &buf[i], 1); if (len < 0) fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); if (len != 1) fatal("ssh_exchange_identification: Connection closed by remote host"); if (buf[i] == '\r') { buf[i] = '\n'; buf[i + 1] = 0; continue; /**XXX wait for \n */ } if (buf[i] == '\n') { buf[i + 1] = 0; break; } } buf[sizeof(buf) - 1] = 0; if (strncmp(buf, "SSH-", 4) == 0) break; debug("ssh_exchange_identification: %s", buf); } server_version_string = xstrdup(buf); /* * Check that the versions match. In future this might accept * several versions and set appropriate flags to handle them. */ if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, remote_version) != 3) fatal("Bad remote protocol version identification: '%.100s'", buf); debug("Remote protocol version %d.%d, remote software version %.100s", remote_major, remote_minor, remote_version); compat_datafellows(remote_version); mismatch = 0; switch(remote_major) { case 1: if (remote_minor == 99 && (options.protocol & SSH_PROTO_2) && !(options.protocol & SSH_PROTO_1_PREFERRED)) { enable_compat20(); break; } if (!(options.protocol & SSH_PROTO_1)) { mismatch = 1; break; } if (remote_minor < 3) { fatal("Remote machine has too old SSH software version."); } else if (remote_minor == 3) { /* We speak 1.3, too. */ enable_compat13(); if (options.forward_agent) { log("Agent forwarding disabled for protocol 1.3"); options.forward_agent = 0; } } break; case 2: if (options.protocol & SSH_PROTO_2) { enable_compat20(); break; } /* FALLTHROUGH */ default: mismatch = 1; break; } if (mismatch) fatal("Protocol major versions differ: %d vs. %d", (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, remote_major); if (compat20) packet_set_ssh2_format(); /* Send our own protocol version identification. */ snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, SSH_VERSION); if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) fatal("write: %.100s", strerror(errno)); client_version_string = xstrdup(buf); chop(client_version_string); chop(server_version_string); debug("Local version string %.100s", client_version_string); } static int read_yes_or_no(const char *prompt, int defval) { char buf[1024]; FILE *f; int retval = -1; if (isatty(0)) f = stdin; else f = fopen("/dev/tty", "rw"); if (f == NULL) return 0; fflush(stdout); while (1) { fprintf(stderr, "%s", prompt); if (fgets(buf, sizeof(buf), f) == NULL) { /* Print a newline (the prompt probably didn\'t have one). */ fprintf(stderr, "\n"); strlcpy(buf, "no", sizeof buf); } /* Remove newline from response. */ if (strchr(buf, '\n')) *strchr(buf, '\n') = 0; if (buf[0] == 0) retval = defval; if (strcmp(buf, "yes") == 0) retval = 1; if (strcmp(buf, "no") == 0) retval = 0; if (retval != -1) { if (f != stdin) fclose(f); return retval; } } } /* * check whether the supplied host key is valid, return only if ok. */ static void check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, const char *user_hostfile, const char *system_hostfile) { Key *file_key; char *type = key_type(host_key); char *ip = NULL; char hostline[1000], *hostp; HostStatus host_status; HostStatus ip_status; int local = 0, host_ip_differ = 0; int salen; char ntop[NI_MAXHOST]; /* * Force accepting of the host key for loopback/localhost. The * problem is that if the home directory is NFS-mounted to multiple * machines, localhost will refer to a different machine in each of * them, and the user will get bogus HOST_CHANGED warnings. This * essentially disables host authentication for localhost; however, * this is probably not a real problem. */ /** hostaddr == 0! */ switch (hostaddr->sa_family) { case AF_INET: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; salen = sizeof(struct sockaddr_in); break; case AF_INET6: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); salen = sizeof(struct sockaddr_in6); break; default: local = 0; salen = sizeof(struct sockaddr_storage); break; } if (local) { debug("Forcing accepting of host key for loopback/localhost."); return; } /* * Turn off check_host_ip for proxy connects, since * we don't have the remote ip-address */ if (options.proxy_command != NULL && options.check_host_ip) options.check_host_ip = 0; if (options.check_host_ip) { if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) fatal("check_host_key: getnameinfo failed"); ip = xstrdup(ntop); } /* * Store the host key from the known host file in here so that we can * compare it with the key for the IP address. */ file_key = key_new(host_key->type); /* * Check if the host key is present in the user\'s list of known * hosts or in the systemwide list. */ host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); if (host_status == HOST_NEW) host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); /* * Also perform check for the ip address, skip the check if we are * localhost or the hostname was an ip address to begin with */ if (options.check_host_ip && !local && strcmp(host, ip)) { Key *ip_key = key_new(host_key->type); ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); if (ip_status == HOST_NEW) ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); if (host_status == HOST_CHANGED && (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) host_ip_differ = 1; key_free(ip_key); } else ip_status = host_status; key_free(file_key); switch (host_status) { case HOST_OK: /* The host is known and the key matches. */ debug("Host '%.200s' is known and matches the %s host key.", host, type); if (options.check_host_ip) { if (ip_status == HOST_NEW) { if (!add_host_to_hostfile(user_hostfile, ip, host_key)) log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", type, ip, user_hostfile); else log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", type, ip); } else if (ip_status != HOST_OK) log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'", type, host, ip); } break; case HOST_NEW: /* The host is new. */ if (options.strict_host_key_checking == 1) { /* User has requested strict host key checking. We will not add the host key automatically. The only alternative left is to abort. */ fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); } else if (options.strict_host_key_checking == 2) { /* The default */ char prompt[1024]; char *fp = key_fingerprint(host_key); snprintf(prompt, sizeof(prompt), "The authenticity of host '%.200s' can't be established.\n" "%s key fingerprint is %s.\n" "Are you sure you want to continue connecting (yes/no)? ", host, type, fp); if (!read_yes_or_no(prompt, -1)) fatal("Aborted by user!\n"); } if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); hostp = hostline; } else hostp = host; /* If not in strict mode, add the key automatically to the local known_hosts file. */ if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) log("Failed to add the host to the list of known hosts (%.500s).", user_hostfile); else log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", hostp, type); break; case HOST_CHANGED: if (options.check_host_ip && host_ip_differ) { char *msg; if (ip_status == HOST_NEW) msg = "is unknown"; else if (ip_status == HOST_OK) msg = "is unchanged"; else msg = "has a different value"; error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("The %s host key for %s has changed,", type, host); error("and the key for the according IP address %s", ip); error("%s. This could either mean that", msg); error("DNS SPOOFING is happening or the IP address for the host"); error("and its host key have changed at the same time"); } /* The host key has changed. */ error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); error("It is also possible that the %s host key has just been changed.", type); error("Please contact your system administrator."); error("Add correct host key in %.100s to get rid of this message.", user_hostfile); /* * If strict host key checking is in use, the user will have * to edit the key manually and we can only abort. */ if (options.strict_host_key_checking) fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); /* * If strict host key checking has not been requested, allow * the connection but without password authentication or * agent forwarding. */ if (options.password_authentication) { error("Password authentication is disabled to avoid trojan horses."); options.password_authentication = 0; } if (options.forward_agent) { error("Agent forwarding is disabled to avoid trojan horses."); options.forward_agent = 0; } /* * XXX Should permit the user to change to use the new id. * This could be done by converting the host key to an * identifying sentence, tell that the host identifies itself * by that sentence, and ask the user if he/she whishes to * accept the authentication. */ break; } if (options.check_host_ip) xfree(ip); } /* * Starts a dialog with the server, and authenticates the current user on the * server. This does not need any extra privileges. The basic connection * to the server must already have been established before this is called. * If login fails, this function prints an error and never returns. * This function does not require super-user privileges. */ static void ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, struct sockaddr *hostaddr, uid_t original_real_uid) { struct passwd *pw; char *host, *cp; char *server_user, *local_user; /* Get local user name. Use it as server user if no user name was given. */ pw = getpwuid(original_real_uid); if (!pw) fatal("User id %u not found from user database.", original_real_uid); local_user = xstrdup(pw->pw_name); server_user = options.user ? options.user : local_user; /* Convert the user-supplied hostname into all lowercase. */ host = xstrdup(orighost); for (cp = host; *cp; cp++) if (isupper(*cp)) *cp = tolower(*cp); /* Exchange protocol version identification strings with the server. */ ssh_exchange_identification(); /* Put the connection into non-blocking mode. */ packet_set_nonblocking(); /* key exchange */ /* authenticate user */ if (compat20) { ssh_kex2(host, hostaddr); ssh_userauth2(server_user, host); } else { ssh_kex(host, hostaddr); ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); } } #endif /* SSH */ #endif /* CK_SSL */ .