1 /* $OpenBSD: sshconnect.c,v 1.212 2008/10/14 18:11:33 stevesk Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
18 #include <sys/types.h>
21 #include <sys/socket.h>
22 #ifdef HAVE_SYS_TIME_H
23 # include <sys/time.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
52 #include "sshconnect.h"
61 char *client_version_string = NULL;
62 char *server_version_string = NULL;
64 static int matching_host_key_dns = 0;
67 extern Options options;
68 extern char *__progname;
69 extern uid_t original_real_uid;
70 extern uid_t original_effective_uid;
71 extern pid_t proxy_command_pid;
73 static int show_other_keys(const char *, Key *);
74 static void warn_changed_key(Key *);
77 * Connect to the given ssh server using a proxy command.
80 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
82 char *command_string, *tmp;
85 char *shell, strport[NI_MAXSERV];
87 if ((shell = getenv("SHELL")) == NULL)
90 /* Convert the port number into a string. */
91 snprintf(strport, sizeof strport, "%hu", port);
94 * Build the final command string in the buffer by making the
95 * appropriate substitutions to the given proxy command.
97 * Use "exec" to avoid "sh -c" processes on some platforms
100 xasprintf(&tmp, "exec %s", proxy_command);
101 command_string = percent_expand(tmp, "h", host,
102 "p", strport, (char *)NULL);
105 /* Create pipes for communicating with the proxy. */
106 if (pipe(pin) < 0 || pipe(pout) < 0)
107 fatal("Could not create pipes to communicate with the proxy: %.100s",
110 debug("Executing proxy command: %.500s", command_string);
112 /* Fork and execute the proxy command. */
113 if ((pid = fork()) == 0) {
116 /* Child. Permanently give up superuser privileges. */
117 permanently_drop_suid(original_real_uid);
119 /* Redirect stdin and stdout. */
122 if (dup2(pin[0], 0) < 0)
123 perror("dup2 stdin");
127 if (dup2(pout[1], 1) < 0)
128 perror("dup2 stdout");
129 /* Cannot be 1 because pin allocated two descriptors. */
132 /* Stderr is left as it is so that error messages get
133 printed on the user's terminal. */
136 argv[2] = command_string;
139 /* Execute the proxy command. Note that we gave up any
140 extra privileges above. */
141 execv(argv[0], argv);
147 fatal("fork failed: %.100s", strerror(errno));
149 proxy_command_pid = pid; /* save pid to clean up later */
151 /* Close child side of the descriptors. */
155 /* Free the command name. */
156 xfree(command_string);
158 /* Set the connection file descriptors. */
159 packet_set_connection(pout[0], pin[1]);
160 packet_set_timeout(options.server_alive_interval,
161 options.server_alive_count_max);
163 /* Indicate OK return */
168 * Set TCP receive buffer if requested.
169 * Note: tuning needs to happen after the socket is
170 * created but before the connection happens
171 * so winscale is negotiated properly -cjr
174 ssh_set_socket_recvbuf(int sock)
176 void *buf = (void *)&options.tcp_rcv_buf;
177 int sz = sizeof(options.tcp_rcv_buf);
179 int socksizelen = sizeof(int);
181 debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf);
182 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
183 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen);
184 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize);
187 error("Couldn't set socket receive buffer to %d: %.100s",
188 options.tcp_rcv_buf, strerror(errno));
193 * Creates a (possibly privileged) socket for use as the ssh connection.
196 ssh_create_socket(int privileged, struct addrinfo *ai)
199 struct addrinfo hints, *res;
202 * If we are running as root and want to connect to a privileged
203 * port, bind our own socket to a privileged port.
206 int p = IPPORT_RESERVED - 1;
208 sock = rresvport_af(&p, ai->ai_family);
211 error("rresvport: af=%d %.100s", ai->ai_family,
214 debug("Allocated local port %d.", p);
216 if (options.tcp_rcv_buf > 0)
217 ssh_set_socket_recvbuf(sock);
220 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
222 error("socket: %.100s", strerror(errno));
225 if (options.tcp_rcv_buf > 0)
226 ssh_set_socket_recvbuf(sock);
228 if (options.tcp_rcv_buf > 0)
229 ssh_set_socket_recvbuf(sock);
231 /* Bind the socket to an alternative local IP address */
232 if (options.bind_address == NULL)
235 memset(&hints, 0, sizeof(hints));
236 hints.ai_family = ai->ai_family;
237 hints.ai_socktype = ai->ai_socktype;
238 hints.ai_protocol = ai->ai_protocol;
239 hints.ai_flags = AI_PASSIVE;
240 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
242 error("getaddrinfo: %s: %s", options.bind_address,
243 ssh_gai_strerror(gaierr));
247 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
248 error("bind: %s: %s", options.bind_address, strerror(errno));
258 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
259 socklen_t addrlen, int *timeoutp)
262 struct timeval tv, t_start;
264 int optval, rc, result = -1;
266 gettimeofday(&t_start, NULL);
268 if (*timeoutp <= 0) {
269 result = connect(sockfd, serv_addr, addrlen);
273 set_nonblock(sockfd);
274 rc = connect(sockfd, serv_addr, addrlen);
276 unset_nonblock(sockfd);
280 if (errno != EINPROGRESS) {
285 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
287 FD_SET(sockfd, fdset);
288 ms_to_timeval(&tv, *timeoutp);
291 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
292 if (rc != -1 || errno != EINTR)
303 debug("select: %s", strerror(errno));
306 /* Completed or failed */
308 optlen = sizeof(optval);
309 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
311 debug("getsockopt: %s", strerror(errno));
319 unset_nonblock(sockfd);
322 /* Should not occur */
323 fatal("Bogus return (%d) from select()", rc);
329 if (result == 0 && *timeoutp > 0) {
330 ms_subtract_diff(&t_start, timeoutp);
331 if (*timeoutp <= 0) {
341 * Opens a TCP/IP connection to the remote server on the given host.
342 * The address of the remote host will be returned in hostaddr.
343 * If port is 0, the default port will be used. If needpriv is true,
344 * a privileged port will be allocated to make the connection.
345 * This requires super-user privileges if needpriv is true.
346 * Connection_attempts specifies the maximum number of tries (one per
347 * second). If proxy_command is non-NULL, it specifies the command (with %h
348 * and %p substituted for host and port, respectively) to use to contact
352 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
353 u_short port, int family, int connection_attempts, int *timeout_ms,
354 int want_keepalive, int needpriv, const char *proxy_command)
358 int sock = -1, attempt;
359 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
360 struct addrinfo hints, *ai, *aitop;
362 debug2("ssh_connect: needpriv %d", needpriv);
364 /* If a proxy command is given, connect using it. */
365 if (proxy_command != NULL)
366 return ssh_proxy_connect(host, port, proxy_command);
368 /* No proxy command. */
370 memset(&hints, 0, sizeof(hints));
371 hints.ai_family = family;
372 hints.ai_socktype = SOCK_STREAM;
373 snprintf(strport, sizeof strport, "%u", port);
374 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
375 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
376 host, ssh_gai_strerror(gaierr));
378 for (attempt = 0; attempt < connection_attempts; attempt++) {
380 /* Sleep a moment before retrying. */
382 debug("Trying again...");
385 * Loop through addresses for this host, and try each one in
386 * sequence until the connection succeeds.
388 for (ai = aitop; ai; ai = ai->ai_next) {
389 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
391 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
392 ntop, sizeof(ntop), strport, sizeof(strport),
393 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
394 error("ssh_connect: getnameinfo failed");
397 debug("Connecting to %.200s [%.100s] port %s.",
398 host, ntop, strport);
400 /* Create a socket for connecting. */
401 sock = ssh_create_socket(needpriv, ai);
403 /* Any error is already output */
406 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
408 /* Successful connection. */
409 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
412 debug("connect to address %s port %s: %s",
413 ntop, strport, strerror(errno));
419 break; /* Successful connection. */
424 /* Return failure if we didn't get a successful connection. */
426 error("ssh: connect to host %s port %s: %s",
427 host, strport, strerror(errno));
431 debug("Connection established.");
433 /* Set SO_KEEPALIVE if requested. */
434 if (want_keepalive &&
435 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
437 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
439 /* Set the connection. */
440 packet_set_connection(sock, sock);
441 packet_set_timeout(options.server_alive_interval,
442 options.server_alive_count_max);
448 * Waits for the server identification string, and sends our own
449 * identification string.
452 ssh_exchange_identification(int timeout_ms)
454 char buf[256], remote_version[256]; /* must be same size! */
455 int remote_major, remote_minor, mismatch;
456 int connection_in = packet_get_connection_in();
457 int connection_out = packet_get_connection_out();
458 int minor1 = PROTOCOL_MINOR_1;
461 int fdsetsz, remaining, rc;
462 struct timeval t_start, t_remaining;
465 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
466 fdset = xcalloc(1, fdsetsz);
468 /* Read other side's version identification. */
469 remaining = timeout_ms;
471 for (i = 0; i < sizeof(buf) - 1; i++) {
472 if (timeout_ms > 0) {
473 gettimeofday(&t_start, NULL);
474 ms_to_timeval(&t_remaining, remaining);
475 FD_SET(connection_in, fdset);
476 rc = select(connection_in + 1, fdset, NULL,
477 fdset, &t_remaining);
478 ms_subtract_diff(&t_start, &remaining);
479 if (rc == 0 || remaining <= 0)
480 fatal("Connection timed out during "
485 fatal("ssh_exchange_identification: "
486 "select: %s", strerror(errno));
490 len = atomicio(read, connection_in, &buf[i], 1);
492 if (len != 1 && errno == EPIPE)
493 fatal("ssh_exchange_identification: "
494 "Connection closed by remote host");
496 fatal("ssh_exchange_identification: "
497 "read: %.100s", strerror(errno));
498 if (buf[i] == '\r') {
501 continue; /**XXX wait for \n */
503 if (buf[i] == '\n') {
508 fatal("ssh_exchange_identification: "
509 "No banner received");
511 buf[sizeof(buf) - 1] = 0;
512 if (strncmp(buf, "SSH-", 4) == 0)
514 debug("ssh_exchange_identification: %s", buf);
516 server_version_string = xstrdup(buf);
520 * Check that the versions match. In future this might accept
521 * several versions and set appropriate flags to handle them.
523 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
524 &remote_major, &remote_minor, remote_version) != 3)
525 fatal("Bad remote protocol version identification: '%.100s'", buf);
526 debug("Remote protocol version %d.%d, remote software version %.100s",
527 remote_major, remote_minor, remote_version);
529 compat_datafellows(remote_version);
532 switch (remote_major) {
534 if (remote_minor == 99 &&
535 (options.protocol & SSH_PROTO_2) &&
536 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
540 if (!(options.protocol & SSH_PROTO_1)) {
544 if (remote_minor < 3) {
545 fatal("Remote machine has too old SSH software version.");
546 } else if (remote_minor == 3 || remote_minor == 4) {
547 /* We speak 1.3, too. */
550 if (options.forward_agent) {
551 logit("Agent forwarding disabled for protocol 1.3");
552 options.forward_agent = 0;
557 if (options.protocol & SSH_PROTO_2) {
567 fatal("Protocol major versions differ: %d vs. %d",
568 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
570 /* Send our own protocol version identification. */
571 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
572 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
573 compat20 ? PROTOCOL_MINOR_2 : minor1,
574 SSH_RELEASE, compat20 ? "\r\n" : "\n");
575 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
576 fatal("write: %.100s", strerror(errno));
577 client_version_string = xstrdup(buf);
578 chop(client_version_string);
579 chop(server_version_string);
580 debug("Local version string %.100s", client_version_string);
583 /* defaults to 'no' */
585 confirm(const char *prompt)
587 const char *msg, *again = "Please type 'yes' or 'no': ";
591 if (options.batch_mode)
593 for (msg = prompt;;msg = again) {
594 p = read_passphrase(msg, RP_ECHO);
596 (p[0] == '\0') || (p[0] == '\n') ||
597 strncasecmp(p, "no", 2) == 0)
599 if (p && strncasecmp(p, "yes", 3) == 0)
609 * check whether the supplied host key is valid, return -1 if the key
610 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
616 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
617 Key *host_key, int readonly, const char *user_hostfile,
618 const char *system_hostfile)
621 const char *type = key_type(host_key);
622 char *ip = NULL, *host = NULL;
623 char hostline[1000], *hostp, *fp, *ra;
624 HostStatus host_status;
625 HostStatus ip_status;
626 int r, local = 0, host_ip_differ = 0;
628 char ntop[NI_MAXHOST];
630 int len, host_line, ip_line, cancelled_forwarding = 0;
631 const char *host_file = NULL, *ip_file = NULL;
634 * Force accepting of the host key for loopback/localhost. The
635 * problem is that if the home directory is NFS-mounted to multiple
636 * machines, localhost will refer to a different machine in each of
637 * them, and the user will get bogus HOST_CHANGED warnings. This
638 * essentially disables host authentication for localhost; however,
639 * this is probably not a real problem.
641 /** hostaddr == 0! */
642 switch (hostaddr->sa_family) {
644 local = (ntohl(((struct sockaddr_in *)hostaddr)->
645 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
646 salen = sizeof(struct sockaddr_in);
649 local = IN6_IS_ADDR_LOOPBACK(
650 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
651 salen = sizeof(struct sockaddr_in6);
655 salen = sizeof(struct sockaddr_storage);
658 if (options.no_host_authentication_for_localhost == 1 && local &&
659 options.host_key_alias == NULL) {
660 debug("Forcing accepting of host key for "
661 "loopback/localhost.");
666 * We don't have the remote ip-address for connections
667 * using a proxy command
669 if (options.proxy_command == NULL) {
670 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
671 NULL, 0, NI_NUMERICHOST) != 0)
672 fatal("check_host_key: getnameinfo failed");
673 ip = put_host_port(ntop, port);
675 ip = xstrdup("<no hostip for proxy command>");
679 * Turn off check_host_ip if the connection is to localhost, via proxy
680 * command or if we don't have a hostname to compare with
682 if (options.check_host_ip && (local ||
683 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
684 options.check_host_ip = 0;
687 * Allow the user to record the key under a different name or
688 * differentiate a non-standard port. This is useful for ssh
689 * tunneling over forwarded connections or if you run multiple
690 * sshd's on different ports on the same machine.
692 if (options.host_key_alias != NULL) {
693 host = xstrdup(options.host_key_alias);
694 debug("using hostkeyalias: %s", host);
696 host = put_host_port(hostname, port);
700 * Store the host key from the known host file in here so that we can
701 * compare it with the key for the IP address.
703 file_key = key_new(host_key->type);
706 * Check if the host key is present in the user's list of known
707 * hosts or in the systemwide list.
709 host_file = user_hostfile;
710 host_status = check_host_in_hostfile(host_file, host, host_key,
711 file_key, &host_line);
712 if (host_status == HOST_NEW) {
713 host_file = system_hostfile;
714 host_status = check_host_in_hostfile(host_file, host, host_key,
715 file_key, &host_line);
718 * Also perform check for the ip address, skip the check if we are
719 * localhost or the hostname was an ip address to begin with
721 if (options.check_host_ip) {
722 Key *ip_key = key_new(host_key->type);
724 ip_file = user_hostfile;
725 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
727 if (ip_status == HOST_NEW) {
728 ip_file = system_hostfile;
729 ip_status = check_host_in_hostfile(ip_file, ip,
730 host_key, ip_key, &ip_line);
732 if (host_status == HOST_CHANGED &&
733 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
738 ip_status = host_status;
742 switch (host_status) {
744 /* The host is known and the key matches. */
745 debug("Host '%.200s' is known and matches the %s host key.",
747 debug("Found key in %s:%d", host_file, host_line);
748 if (options.check_host_ip && ip_status == HOST_NEW) {
750 logit("%s host key for IP address "
751 "'%.128s' not in list of known hosts.",
753 else if (!add_host_to_hostfile(user_hostfile, ip,
754 host_key, options.hash_known_hosts))
755 logit("Failed to add the %s host key for IP "
756 "address '%.128s' to the list of known "
757 "hosts (%.30s).", type, ip, user_hostfile);
759 logit("Warning: Permanently added the %s host "
760 "key for IP address '%.128s' to the list "
761 "of known hosts.", type, ip);
762 } else if (options.visual_host_key) {
763 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
764 ra = key_fingerprint(host_key, SSH_FP_MD5,
766 logit("Host key fingerprint is %s\n%s\n", fp, ra);
772 if (options.host_key_alias == NULL && port != 0 &&
773 port != SSH_DEFAULT_PORT) {
774 debug("checking without port identifier");
775 if (check_host_key(hostname, hostaddr, 0, host_key,
776 ROQUIET, user_hostfile, system_hostfile) == 0) {
777 debug("found matching key w/out port");
783 /* The host is new. */
784 if (options.strict_host_key_checking == 1) {
786 * User has requested strict host key checking. We
787 * will not add the host key automatically. The only
788 * alternative left is to abort.
790 error("No %s host key is known for %.200s and you "
791 "have requested strict checking.", type, host);
793 } else if (options.strict_host_key_checking == 2) {
794 char msg1[1024], msg2[1024];
796 if (show_other_keys(host, host_key))
797 snprintf(msg1, sizeof(msg1),
798 "\nbut keys of different type are already"
799 " known for this host.");
801 snprintf(msg1, sizeof(msg1), ".");
803 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
804 ra = key_fingerprint(host_key, SSH_FP_MD5,
807 if (options.verify_host_key_dns) {
808 if (matching_host_key_dns)
809 snprintf(msg2, sizeof(msg2),
810 "Matching host key fingerprint"
813 snprintf(msg2, sizeof(msg2),
814 "No matching host key fingerprint"
817 snprintf(msg, sizeof(msg),
818 "The authenticity of host '%.200s (%s)' can't be "
820 "%s key fingerprint is %s.%s%s\n%s"
821 "Are you sure you want to continue connecting "
823 host, ip, msg1, type, fp,
824 options.visual_host_key ? "\n" : "",
825 options.visual_host_key ? ra : "",
833 * If not in strict mode, add the key automatically to the
834 * local known_hosts file.
836 if (options.check_host_ip && ip_status == HOST_NEW) {
837 snprintf(hostline, sizeof(hostline), "%s,%s",
840 if (options.hash_known_hosts) {
841 /* Add hash of host and IP separately */
842 r = add_host_to_hostfile(user_hostfile, host,
843 host_key, options.hash_known_hosts) &&
844 add_host_to_hostfile(user_hostfile, ip,
845 host_key, options.hash_known_hosts);
847 /* Add unhashed "host,ip" */
848 r = add_host_to_hostfile(user_hostfile,
850 options.hash_known_hosts);
853 r = add_host_to_hostfile(user_hostfile, host, host_key,
854 options.hash_known_hosts);
859 logit("Failed to add the host to the list of known "
860 "hosts (%.500s).", user_hostfile);
862 logit("Warning: Permanently added '%.200s' (%s) to the "
863 "list of known hosts.", hostp, type);
866 if (readonly == ROQUIET)
868 if (options.check_host_ip && host_ip_differ) {
870 if (ip_status == HOST_NEW)
871 key_msg = "is unknown";
872 else if (ip_status == HOST_OK)
873 key_msg = "is unchanged";
875 key_msg = "has a different value";
876 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
877 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
878 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
879 error("The %s host key for %s has changed,", type, host);
880 error("and the key for the corresponding IP address %s", ip);
881 error("%s. This could either mean that", key_msg);
882 error("DNS SPOOFING is happening or the IP address for the host");
883 error("and its host key have changed at the same time.");
884 if (ip_status != HOST_NEW)
885 error("Offending key for IP in %s:%d", ip_file, ip_line);
887 /* The host key has changed. */
888 warn_changed_key(host_key);
889 error("Add correct host key in %.100s to get rid of this message.",
891 error("Offending key in %s:%d", host_file, host_line);
894 * If strict host key checking is in use, the user will have
895 * to edit the key manually and we can only abort.
897 if (options.strict_host_key_checking) {
898 error("%s host key for %.200s has changed and you have "
899 "requested strict checking.", type, host);
904 * If strict host key checking has not been requested, allow
905 * the connection but without MITM-able authentication or
908 if (options.password_authentication) {
909 error("Password authentication is disabled to avoid "
910 "man-in-the-middle attacks.");
911 options.password_authentication = 0;
912 cancelled_forwarding = 1;
914 if (options.kbd_interactive_authentication) {
915 error("Keyboard-interactive authentication is disabled"
916 " to avoid man-in-the-middle attacks.");
917 options.kbd_interactive_authentication = 0;
918 options.challenge_response_authentication = 0;
919 cancelled_forwarding = 1;
921 if (options.challenge_response_authentication) {
922 error("Challenge/response authentication is disabled"
923 " to avoid man-in-the-middle attacks.");
924 options.challenge_response_authentication = 0;
925 cancelled_forwarding = 1;
927 if (options.forward_agent) {
928 error("Agent forwarding is disabled to avoid "
929 "man-in-the-middle attacks.");
930 options.forward_agent = 0;
931 cancelled_forwarding = 1;
933 if (options.forward_x11) {
934 error("X11 forwarding is disabled to avoid "
935 "man-in-the-middle attacks.");
936 options.forward_x11 = 0;
937 cancelled_forwarding = 1;
939 if (options.num_local_forwards > 0 ||
940 options.num_remote_forwards > 0) {
941 error("Port forwarding is disabled to avoid "
942 "man-in-the-middle attacks.");
943 options.num_local_forwards =
944 options.num_remote_forwards = 0;
945 cancelled_forwarding = 1;
947 if (options.tun_open != SSH_TUNMODE_NO) {
948 error("Tunnel forwarding is disabled to avoid "
949 "man-in-the-middle attacks.");
950 options.tun_open = SSH_TUNMODE_NO;
951 cancelled_forwarding = 1;
953 if (options.exit_on_forward_failure && cancelled_forwarding)
954 fatal("Error: forwarding disabled due to host key "
958 * XXX Should permit the user to change to use the new id.
959 * This could be done by converting the host key to an
960 * identifying sentence, tell that the host identifies itself
961 * by that sentence, and ask the user if he/she whishes to
962 * accept the authentication.
966 fatal("internal error");
970 if (options.check_host_ip && host_status != HOST_CHANGED &&
971 ip_status == HOST_CHANGED) {
972 snprintf(msg, sizeof(msg),
973 "Warning: the %s host key for '%.200s' "
974 "differs from the key for the IP address '%.128s'"
975 "\nOffending key for IP in %s:%d",
976 type, host, ip, ip_file, ip_line);
977 if (host_status == HOST_OK) {
979 snprintf(msg + len, sizeof(msg) - len,
980 "\nMatching host key in %s:%d",
981 host_file, host_line);
983 if (options.strict_host_key_checking == 1) {
985 error("Exiting, you have requested strict checking.");
987 } else if (options.strict_host_key_checking == 2) {
988 strlcat(msg, "\nAre you sure you want "
989 "to continue connecting (yes/no)? ", sizeof(msg));
1007 /* returns 0 if key verifies or -1 if key does NOT verify */
1009 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1014 if (options.verify_host_key_dns &&
1015 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1017 if (flags & DNS_VERIFY_FOUND) {
1019 if (options.verify_host_key_dns == 1 &&
1020 flags & DNS_VERIFY_MATCH &&
1021 flags & DNS_VERIFY_SECURE)
1024 if (flags & DNS_VERIFY_MATCH) {
1025 matching_host_key_dns = 1;
1027 warn_changed_key(host_key);
1028 error("Update the SSHFP RR in DNS with the new "
1029 "host key to get rid of this message.");
1034 /* return ok if the key can be found in an old keyfile */
1035 if (stat(options.system_hostfile2, &st) == 0 ||
1036 stat(options.user_hostfile2, &st) == 0) {
1037 if (check_host_key(host, hostaddr, options.port, host_key,
1038 RDONLY, options.user_hostfile2,
1039 options.system_hostfile2) == 0)
1042 return check_host_key(host, hostaddr, options.port, host_key,
1043 RDRW, options.user_hostfile, options.system_hostfile);
1047 * Starts a dialog with the server, and authenticates the current user on the
1048 * server. This does not need any extra privileges. The basic connection
1049 * to the server must already have been established before this is called.
1050 * If login fails, this function prints an error and never returns.
1051 * This function does not require super-user privileges.
1054 ssh_login(Sensitive *sensitive, const char *orighost,
1055 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1058 char *server_user, *local_user;
1060 local_user = xstrdup(pw->pw_name);
1061 server_user = options.user ? options.user : local_user;
1063 /* Convert the user-supplied hostname into all lowercase. */
1064 host = xstrdup(orighost);
1065 for (cp = host; *cp; cp++)
1067 *cp = (char)tolower(*cp);
1069 /* Exchange protocol version identification strings with the server. */
1070 ssh_exchange_identification(timeout_ms);
1072 /* Put the connection into non-blocking mode. */
1073 packet_set_nonblocking();
1076 /* authenticate user */
1078 ssh_kex2(host, hostaddr);
1079 ssh_userauth2(local_user, server_user, host, sensitive);
1081 ssh_kex(host, hostaddr);
1082 ssh_userauth1(local_user, server_user, host, sensitive);
1088 ssh_put_password(char *password)
1093 if (datafellows & SSH_BUG_PASSWORDPAD) {
1094 packet_put_cstring(password);
1097 size = roundup(strlen(password) + 1, 32);
1098 padded = xcalloc(1, size);
1099 strlcpy(padded, password, size);
1100 packet_put_string(padded, size);
1101 memset(padded, 0, size);
1106 show_key_from_file(const char *file, const char *host, int keytype)
1112 found = key_new(keytype);
1113 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1114 keytype, found, &line))) {
1115 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1116 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1117 logit("WARNING: %s key found for host %s\n"
1119 "%s key fingerprint %s.\n%s\n",
1120 key_type(found), host, file, line,
1121 key_type(found), fp, ra);
1129 /* print all known host keys for a given host, but skip keys of given type */
1131 show_other_keys(const char *host, Key *key)
1133 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1136 for (i = 0; type[i] != -1; i++) {
1137 if (type[i] == key->type)
1139 if (type[i] != KEY_RSA1 &&
1140 show_key_from_file(options.user_hostfile2, host, type[i])) {
1144 if (type[i] != KEY_RSA1 &&
1145 show_key_from_file(options.system_hostfile2, host, type[i])) {
1149 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1153 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1157 debug2("no key of type %d for host %s", type[i], host);
1163 warn_changed_key(Key *host_key)
1166 const char *type = key_type(host_key);
1168 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1170 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1171 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1172 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1173 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1174 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1175 error("It is also possible that the %s host key has just been changed.", type);
1176 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1178 error("Please contact your system administrator.");
1184 * Execute a local command
1187 ssh_local_cmd(const char *args)
1193 if (!options.permit_local_command ||
1194 args == NULL || !*args)
1197 if ((shell = getenv("SHELL")) == NULL)
1198 shell = _PATH_BSHELL;
1202 debug3("Executing %s -c \"%s\"", shell, args);
1203 execl(shell, shell, "-c", args, (char *)NULL);
1204 error("Couldn't execute %s -c \"%s\": %s",
1205 shell, args, strerror(errno));
1207 } else if (pid == -1)
1208 fatal("fork failed: %.100s", strerror(errno));
1209 while (waitpid(pid, &status, 0) == -1)
1211 fatal("Couldn't wait for child: %s", strerror(errno));
1213 if (!WIFEXITED(status))
1216 return (WEXITSTATUS(status));