1 /* $OpenBSD: sshconnect.c,v 1.211 2008/07/01 07:24:22 dtucker Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * Code to connect to a remote host, and to perform the client side of the
8 * login (authentication) dialog.
10 * As far as I am concerned, the code I have written for this software
11 * can be used freely for any purpose. Any derived versions of this
12 * software must be clearly marked as such, and if the derived work is
13 * incompatible with the protocol description in the RFC file, it must be
14 * called by a name other than "ssh" or "Secure Shell".
19 #include <sys/types.h>
22 #include <sys/socket.h>
23 #ifdef HAVE_SYS_TIME_H
24 # include <sys/time.h>
27 #include <netinet/in.h>
28 #include <arpa/inet.h>
53 #include "sshconnect.h"
62 char *client_version_string = NULL;
63 char *server_version_string = NULL;
65 static int matching_host_key_dns = 0;
68 extern Options options;
69 extern char *__progname;
70 extern uid_t original_real_uid;
71 extern uid_t original_effective_uid;
72 extern pid_t proxy_command_pid;
74 #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
75 #define INET6_ADDRSTRLEN 46
78 static int show_other_keys(const char *, Key *);
79 static void warn_changed_key(Key *);
82 * Connect to the given ssh server using a proxy command.
85 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
87 char *command_string, *tmp;
90 char *shell, strport[NI_MAXSERV];
92 if ((shell = getenv("SHELL")) == NULL)
95 /* Convert the port number into a string. */
96 snprintf(strport, sizeof strport, "%hu", port);
99 * Build the final command string in the buffer by making the
100 * appropriate substitutions to the given proxy command.
102 * Use "exec" to avoid "sh -c" processes on some platforms
105 xasprintf(&tmp, "exec %s", proxy_command);
106 command_string = percent_expand(tmp, "h", host,
107 "p", strport, (char *)NULL);
110 /* Create pipes for communicating with the proxy. */
111 if (pipe(pin) < 0 || pipe(pout) < 0)
112 fatal("Could not create pipes to communicate with the proxy: %.100s",
115 debug("Executing proxy command: %.500s", command_string);
117 /* Fork and execute the proxy command. */
118 if ((pid = fork()) == 0) {
121 /* Child. Permanently give up superuser privileges. */
122 permanently_drop_suid(original_real_uid);
124 /* Redirect stdin and stdout. */
127 if (dup2(pin[0], 0) < 0)
128 perror("dup2 stdin");
132 if (dup2(pout[1], 1) < 0)
133 perror("dup2 stdout");
134 /* Cannot be 1 because pin allocated two descriptors. */
137 /* Stderr is left as it is so that error messages get
138 printed on the user's terminal. */
141 argv[2] = command_string;
144 /* Execute the proxy command. Note that we gave up any
145 extra privileges above. */
146 execv(argv[0], argv);
152 fatal("fork failed: %.100s", strerror(errno));
154 proxy_command_pid = pid; /* save pid to clean up later */
156 /* Close child side of the descriptors. */
160 /* Free the command name. */
161 xfree(command_string);
163 /* Set the connection file descriptors. */
164 packet_set_connection(pout[0], pin[1]);
165 packet_set_timeout(options.server_alive_interval,
166 options.server_alive_count_max);
168 /* Indicate OK return */
173 * Creates a (possibly privileged) socket for use as the ssh connection.
176 ssh_create_socket(int privileged, struct addrinfo *ai)
179 struct addrinfo hints, *res;
182 * If we are running as root and want to connect to a privileged
183 * port, bind our own socket to a privileged port.
186 int p = IPPORT_RESERVED - 1;
188 sock = rresvport_af(&p, ai->ai_family);
191 error("rresvport: af=%d %.100s", ai->ai_family,
194 debug("Allocated local port %d.", p);
197 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
199 error("socket: %.100s", strerror(errno));
201 /* Bind the socket to an alternative local IP address */
202 if (options.bind_address == NULL)
205 memset(&hints, 0, sizeof(hints));
206 hints.ai_family = ai->ai_family;
207 hints.ai_socktype = ai->ai_socktype;
208 hints.ai_protocol = ai->ai_protocol;
209 hints.ai_flags = AI_PASSIVE;
210 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
212 error("getaddrinfo: %s: %s", options.bind_address,
213 ssh_gai_strerror(gaierr));
217 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
218 error("bind: %s: %s", options.bind_address, strerror(errno));
228 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
229 socklen_t addrlen, int *timeoutp)
232 struct timeval tv, t_start;
234 int optval, rc, result = -1;
236 gettimeofday(&t_start, NULL);
238 if (*timeoutp <= 0) {
239 result = connect(sockfd, serv_addr, addrlen);
243 set_nonblock(sockfd);
244 rc = connect(sockfd, serv_addr, addrlen);
246 unset_nonblock(sockfd);
250 if (errno != EINPROGRESS) {
255 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
257 FD_SET(sockfd, fdset);
258 ms_to_timeval(&tv, *timeoutp);
261 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
262 if (rc != -1 || errno != EINTR)
273 debug("select: %s", strerror(errno));
276 /* Completed or failed */
278 optlen = sizeof(optval);
279 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
281 debug("getsockopt: %s", strerror(errno));
289 unset_nonblock(sockfd);
292 /* Should not occur */
293 fatal("Bogus return (%d) from select()", rc);
299 if (result == 0 && *timeoutp > 0) {
300 ms_subtract_diff(&t_start, timeoutp);
301 if (*timeoutp <= 0) {
311 * Opens a TCP/IP connection to the remote server on the given host.
312 * The address of the remote host will be returned in hostaddr.
313 * If port is 0, the default port will be used. If needpriv is true,
314 * a privileged port will be allocated to make the connection.
315 * This requires super-user privileges if needpriv is true.
316 * Connection_attempts specifies the maximum number of tries (one per
317 * second). If proxy_command is non-NULL, it specifies the command (with %h
318 * and %p substituted for host and port, respectively) to use to contact
322 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
323 u_short port, int family, int connection_attempts, int *timeout_ms,
324 int want_keepalive, int needpriv, const char *proxy_command)
328 int sock = -1, attempt;
329 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
330 struct addrinfo hints, *ai, *aitop;
332 debug2("ssh_connect: needpriv %d", needpriv);
334 /* If a proxy command is given, connect using it. */
335 if (proxy_command != NULL)
336 return ssh_proxy_connect(host, port, proxy_command);
338 /* No proxy command. */
340 memset(&hints, 0, sizeof(hints));
341 hints.ai_family = family;
342 hints.ai_socktype = SOCK_STREAM;
343 snprintf(strport, sizeof strport, "%u", port);
344 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
345 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
346 host, ssh_gai_strerror(gaierr));
348 for (attempt = 0; attempt < connection_attempts; attempt++) {
350 /* Sleep a moment before retrying. */
352 debug("Trying again...");
355 * Loop through addresses for this host, and try each one in
356 * sequence until the connection succeeds.
358 for (ai = aitop; ai; ai = ai->ai_next) {
359 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
361 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
362 ntop, sizeof(ntop), strport, sizeof(strport),
363 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
364 error("ssh_connect: getnameinfo failed");
367 debug("Connecting to %.200s [%.100s] port %s.",
368 host, ntop, strport);
370 /* Create a socket for connecting. */
371 sock = ssh_create_socket(needpriv, ai);
373 /* Any error is already output */
376 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
378 /* Successful connection. */
379 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
382 debug("connect to address %s port %s: %s",
383 ntop, strport, strerror(errno));
389 break; /* Successful connection. */
394 /* Return failure if we didn't get a successful connection. */
396 error("ssh: connect to host %s port %s: %s",
397 host, strport, strerror(errno));
401 debug("Connection established.");
403 /* Set SO_KEEPALIVE if requested. */
404 if (want_keepalive &&
405 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
407 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
409 /* Set the connection. */
410 packet_set_connection(sock, sock);
411 packet_set_timeout(options.server_alive_interval,
412 options.server_alive_count_max);
418 * Waits for the server identification string, and sends our own
419 * identification string.
422 ssh_exchange_identification(int timeout_ms)
424 char buf[256], remote_version[256]; /* must be same size! */
425 int remote_major, remote_minor, mismatch;
426 int connection_in = packet_get_connection_in();
427 int connection_out = packet_get_connection_out();
428 int minor1 = PROTOCOL_MINOR_1;
431 int fdsetsz, remaining, rc;
432 struct timeval t_start, t_remaining;
435 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
436 fdset = xcalloc(1, fdsetsz);
438 /* Read other side's version identification. */
439 remaining = timeout_ms;
441 for (i = 0; i < sizeof(buf) - 1; i++) {
442 if (timeout_ms > 0) {
443 gettimeofday(&t_start, NULL);
444 ms_to_timeval(&t_remaining, remaining);
445 FD_SET(connection_in, fdset);
446 rc = select(connection_in + 1, fdset, NULL,
447 fdset, &t_remaining);
448 ms_subtract_diff(&t_start, &remaining);
449 if (rc == 0 || remaining <= 0)
450 fatal("Connection timed out during "
455 fatal("ssh_exchange_identification: "
456 "select: %s", strerror(errno));
460 len = atomicio(read, connection_in, &buf[i], 1);
462 if (len != 1 && errno == EPIPE)
463 fatal("ssh_exchange_identification: "
464 "Connection closed by remote host");
466 fatal("ssh_exchange_identification: "
467 "read: %.100s", strerror(errno));
468 if (buf[i] == '\r') {
471 continue; /**XXX wait for \n */
473 if (buf[i] == '\n') {
478 fatal("ssh_exchange_identification: "
479 "No banner received");
481 buf[sizeof(buf) - 1] = 0;
482 if (strncmp(buf, "SSH-", 4) == 0)
484 debug("ssh_exchange_identification: %s", buf);
486 server_version_string = xstrdup(buf);
490 * Check that the versions match. In future this might accept
491 * several versions and set appropriate flags to handle them.
493 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
494 &remote_major, &remote_minor, remote_version) != 3)
495 fatal("Bad remote protocol version identification: '%.100s'", buf);
496 debug("Remote protocol version %d.%d, remote software version %.100s",
497 remote_major, remote_minor, remote_version);
499 compat_datafellows(remote_version);
502 switch (remote_major) {
504 if (remote_minor == 99 &&
505 (options.protocol & SSH_PROTO_2) &&
506 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
510 if (!(options.protocol & SSH_PROTO_1)) {
514 if (remote_minor < 3) {
515 fatal("Remote machine has too old SSH software version.");
516 } else if (remote_minor == 3 || remote_minor == 4) {
517 /* We speak 1.3, too. */
520 if (options.forward_agent) {
521 logit("Agent forwarding disabled for protocol 1.3");
522 options.forward_agent = 0;
527 if (options.protocol & SSH_PROTO_2) {
537 fatal("Protocol major versions differ: %d vs. %d",
538 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
540 /* Send our own protocol version identification. */
541 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
542 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
543 compat20 ? PROTOCOL_MINOR_2 : minor1,
544 SSH_VERSION, compat20 ? "\r\n" : "\n");
545 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
546 fatal("write: %.100s", strerror(errno));
547 client_version_string = xstrdup(buf);
548 chop(client_version_string);
549 chop(server_version_string);
550 debug("Local version string %.100s", client_version_string);
553 /* defaults to 'no' */
555 confirm(const char *prompt)
557 const char *msg, *again = "Please type 'yes' or 'no': ";
561 if (options.batch_mode)
563 for (msg = prompt;;msg = again) {
564 p = read_passphrase(msg, RP_ECHO);
566 (p[0] == '\0') || (p[0] == '\n') ||
567 strncasecmp(p, "no", 2) == 0)
569 if (p && strncasecmp(p, "yes", 3) == 0)
579 * check whether the supplied host key is valid, return -1 if the key
580 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
586 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
587 Key *host_key, int readonly, const char *user_hostfile,
588 const char *system_hostfile)
591 const char *type = key_type(host_key);
592 char *ip = NULL, *host = NULL;
593 char hostline[1000], *hostp, *fp, *ra;
594 HostStatus host_status;
595 HostStatus ip_status;
596 int r, local = 0, host_ip_differ = 0;
598 char ntop[NI_MAXHOST];
600 int len, host_line, ip_line, cancelled_forwarding = 0;
601 const char *host_file = NULL, *ip_file = NULL;
604 * Force accepting of the host key for loopback/localhost. The
605 * problem is that if the home directory is NFS-mounted to multiple
606 * machines, localhost will refer to a different machine in each of
607 * them, and the user will get bogus HOST_CHANGED warnings. This
608 * essentially disables host authentication for localhost; however,
609 * this is probably not a real problem.
611 /** hostaddr == 0! */
612 switch (hostaddr->sa_family) {
614 local = (ntohl(((struct sockaddr_in *)hostaddr)->
615 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
616 salen = sizeof(struct sockaddr_in);
619 local = IN6_IS_ADDR_LOOPBACK(
620 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
621 salen = sizeof(struct sockaddr_in6);
625 salen = sizeof(struct sockaddr_storage);
628 if (options.no_host_authentication_for_localhost == 1 && local &&
629 options.host_key_alias == NULL) {
630 debug("Forcing accepting of host key for "
631 "loopback/localhost.");
636 * We don't have the remote ip-address for connections
637 * using a proxy command
639 if (options.proxy_command == NULL) {
640 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
641 NULL, 0, NI_NUMERICHOST) != 0)
642 fatal("check_host_key: getnameinfo failed");
643 ip = put_host_port(ntop, port);
645 ip = xstrdup("<no hostip for proxy command>");
649 * Turn off check_host_ip if the connection is to localhost, via proxy
650 * command or if we don't have a hostname to compare with
652 if (options.check_host_ip && (local ||
653 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
654 options.check_host_ip = 0;
657 * Allow the user to record the key under a different name or
658 * differentiate a non-standard port. This is useful for ssh
659 * tunneling over forwarded connections or if you run multiple
660 * sshd's on different ports on the same machine.
662 if (options.host_key_alias != NULL) {
663 host = xstrdup(options.host_key_alias);
664 debug("using hostkeyalias: %s", host);
666 host = put_host_port(hostname, port);
670 * Store the host key from the known host file in here so that we can
671 * compare it with the key for the IP address.
673 file_key = key_new(host_key->type);
676 * Check if the host key is present in the user's list of known
677 * hosts or in the systemwide list.
679 host_file = user_hostfile;
680 host_status = check_host_in_hostfile(host_file, host, host_key,
681 file_key, &host_line);
682 if (host_status == HOST_NEW) {
683 host_file = system_hostfile;
684 host_status = check_host_in_hostfile(host_file, host, host_key,
685 file_key, &host_line);
688 * Also perform check for the ip address, skip the check if we are
689 * localhost or the hostname was an ip address to begin with
691 if (options.check_host_ip) {
692 Key *ip_key = key_new(host_key->type);
694 ip_file = user_hostfile;
695 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
697 if (ip_status == HOST_NEW) {
698 ip_file = system_hostfile;
699 ip_status = check_host_in_hostfile(ip_file, ip,
700 host_key, ip_key, &ip_line);
702 if (host_status == HOST_CHANGED &&
703 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
708 ip_status = host_status;
712 switch (host_status) {
714 /* The host is known and the key matches. */
715 debug("Host '%.200s' is known and matches the %s host key.",
717 debug("Found key in %s:%d", host_file, host_line);
718 if (options.check_host_ip && ip_status == HOST_NEW) {
720 logit("%s host key for IP address "
721 "'%.128s' not in list of known hosts.",
723 else if (!add_host_to_hostfile(user_hostfile, ip,
724 host_key, options.hash_known_hosts))
725 logit("Failed to add the %s host key for IP "
726 "address '%.128s' to the list of known "
727 "hosts (%.30s).", type, ip, user_hostfile);
729 logit("Warning: Permanently added the %s host "
730 "key for IP address '%.128s' to the list "
731 "of known hosts.", type, ip);
732 } else if (options.visual_host_key) {
733 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
734 ra = key_fingerprint(host_key, SSH_FP_MD5,
736 logit("Host key fingerprint is %s\n%s\n", fp, ra);
742 if (options.host_key_alias == NULL && port != 0 &&
743 port != SSH_DEFAULT_PORT) {
744 debug("checking without port identifier");
745 if (check_host_key(hostname, hostaddr, 0, host_key, 2,
746 user_hostfile, system_hostfile) == 0) {
747 debug("found matching key w/out port");
753 /* The host is new. */
754 if (options.strict_host_key_checking == 1) {
756 * User has requested strict host key checking. We
757 * will not add the host key automatically. The only
758 * alternative left is to abort.
760 error("No %s host key is known for %.200s and you "
761 "have requested strict checking.", type, host);
763 } else if (options.strict_host_key_checking == 2) {
764 char msg1[1024], msg2[1024];
766 if (show_other_keys(host, host_key))
767 snprintf(msg1, sizeof(msg1),
768 "\nbut keys of different type are already"
769 " known for this host.");
771 snprintf(msg1, sizeof(msg1), ".");
773 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
774 ra = key_fingerprint(host_key, SSH_FP_MD5,
777 if (options.verify_host_key_dns) {
778 if (matching_host_key_dns)
779 snprintf(msg2, sizeof(msg2),
780 "Matching host key fingerprint"
783 snprintf(msg2, sizeof(msg2),
784 "No matching host key fingerprint"
787 snprintf(msg, sizeof(msg),
788 "The authenticity of host '%.200s (%s)' can't be "
790 "%s key fingerprint is %s.%s%s\n%s"
791 "Are you sure you want to continue connecting "
793 host, ip, msg1, type, fp,
794 options.visual_host_key ? "\n" : "",
795 options.visual_host_key ? ra : "",
803 * If not in strict mode, add the key automatically to the
804 * local known_hosts file.
806 if (options.check_host_ip && ip_status == HOST_NEW) {
807 snprintf(hostline, sizeof(hostline), "%s,%s",
810 if (options.hash_known_hosts) {
811 /* Add hash of host and IP separately */
812 r = add_host_to_hostfile(user_hostfile, host,
813 host_key, options.hash_known_hosts) &&
814 add_host_to_hostfile(user_hostfile, ip,
815 host_key, options.hash_known_hosts);
817 /* Add unhashed "host,ip" */
818 r = add_host_to_hostfile(user_hostfile,
820 options.hash_known_hosts);
823 r = add_host_to_hostfile(user_hostfile, host, host_key,
824 options.hash_known_hosts);
829 logit("Failed to add the host to the list of known "
830 "hosts (%.500s).", user_hostfile);
832 logit("Warning: Permanently added '%.200s' (%s) to the "
833 "list of known hosts.", hostp, type);
836 if (readonly == ROQUIET)
838 if (options.check_host_ip && host_ip_differ) {
840 if (ip_status == HOST_NEW)
841 key_msg = "is unknown";
842 else if (ip_status == HOST_OK)
843 key_msg = "is unchanged";
845 key_msg = "has a different value";
846 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
847 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
848 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
849 error("The %s host key for %s has changed,", type, host);
850 error("and the key for the corresponding IP address %s", ip);
851 error("%s. This could either mean that", key_msg);
852 error("DNS SPOOFING is happening or the IP address for the host");
853 error("and its host key have changed at the same time.");
854 if (ip_status != HOST_NEW)
855 error("Offending key for IP in %s:%d", ip_file, ip_line);
857 /* The host key has changed. */
858 warn_changed_key(host_key);
859 error("Add correct host key in %.100s to get rid of this message.",
861 error("Offending key in %s:%d", host_file, host_line);
864 * If strict host key checking is in use, the user will have
865 * to edit the key manually and we can only abort.
867 if (options.strict_host_key_checking) {
868 error("%s host key for %.200s has changed and you have "
869 "requested strict checking.", type, host);
874 * If strict host key checking has not been requested, allow
875 * the connection but without MITM-able authentication or
878 if (options.password_authentication) {
879 error("Password authentication is disabled to avoid "
880 "man-in-the-middle attacks.");
881 options.password_authentication = 0;
882 cancelled_forwarding = 1;
884 if (options.kbd_interactive_authentication) {
885 error("Keyboard-interactive authentication is disabled"
886 " to avoid man-in-the-middle attacks.");
887 options.kbd_interactive_authentication = 0;
888 options.challenge_response_authentication = 0;
889 cancelled_forwarding = 1;
891 if (options.challenge_response_authentication) {
892 error("Challenge/response authentication is disabled"
893 " to avoid man-in-the-middle attacks.");
894 options.challenge_response_authentication = 0;
895 cancelled_forwarding = 1;
897 if (options.forward_agent) {
898 error("Agent forwarding is disabled to avoid "
899 "man-in-the-middle attacks.");
900 options.forward_agent = 0;
901 cancelled_forwarding = 1;
903 if (options.forward_x11) {
904 error("X11 forwarding is disabled to avoid "
905 "man-in-the-middle attacks.");
906 options.forward_x11 = 0;
907 cancelled_forwarding = 1;
909 if (options.num_local_forwards > 0 ||
910 options.num_remote_forwards > 0) {
911 error("Port forwarding is disabled to avoid "
912 "man-in-the-middle attacks.");
913 options.num_local_forwards =
914 options.num_remote_forwards = 0;
915 cancelled_forwarding = 1;
917 if (options.tun_open != SSH_TUNMODE_NO) {
918 error("Tunnel forwarding is disabled to avoid "
919 "man-in-the-middle attacks.");
920 options.tun_open = SSH_TUNMODE_NO;
921 cancelled_forwarding = 1;
923 if (options.exit_on_forward_failure && cancelled_forwarding)
924 fatal("Error: forwarding disabled due to host key "
928 * XXX Should permit the user to change to use the new id.
929 * This could be done by converting the host key to an
930 * identifying sentence, tell that the host identifies itself
931 * by that sentence, and ask the user if he/she whishes to
932 * accept the authentication.
936 fatal("internal error");
940 if (options.check_host_ip && host_status != HOST_CHANGED &&
941 ip_status == HOST_CHANGED) {
942 snprintf(msg, sizeof(msg),
943 "Warning: the %s host key for '%.200s' "
944 "differs from the key for the IP address '%.128s'"
945 "\nOffending key for IP in %s:%d",
946 type, host, ip, ip_file, ip_line);
947 if (host_status == HOST_OK) {
949 snprintf(msg + len, sizeof(msg) - len,
950 "\nMatching host key in %s:%d",
951 host_file, host_line);
953 if (options.strict_host_key_checking == 1) {
955 error("Exiting, you have requested strict checking.");
957 } else if (options.strict_host_key_checking == 2) {
958 strlcat(msg, "\nAre you sure you want "
959 "to continue connecting (yes/no)? ", sizeof(msg));
977 /* returns 0 if key verifies or -1 if key does NOT verify */
979 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
984 if (options.verify_host_key_dns &&
985 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
987 if (flags & DNS_VERIFY_FOUND) {
989 if (options.verify_host_key_dns == 1 &&
990 flags & DNS_VERIFY_MATCH &&
991 flags & DNS_VERIFY_SECURE)
994 if (flags & DNS_VERIFY_MATCH) {
995 matching_host_key_dns = 1;
997 warn_changed_key(host_key);
998 error("Update the SSHFP RR in DNS with the new "
999 "host key to get rid of this message.");
1004 /* return ok if the key can be found in an old keyfile */
1005 if (stat(options.system_hostfile2, &st) == 0 ||
1006 stat(options.user_hostfile2, &st) == 0) {
1007 if (check_host_key(host, hostaddr, options.port, host_key,
1008 RDONLY, options.user_hostfile2,
1009 options.system_hostfile2) == 0)
1012 return check_host_key(host, hostaddr, options.port, host_key,
1013 RDRW, options.user_hostfile, options.system_hostfile);
1017 * Starts a dialog with the server, and authenticates the current user on the
1018 * server. This does not need any extra privileges. The basic connection
1019 * to the server must already have been established before this is called.
1020 * If login fails, this function prints an error and never returns.
1021 * This function does not require super-user privileges.
1024 ssh_login(Sensitive *sensitive, const char *orighost,
1025 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1028 char *server_user, *local_user;
1030 local_user = xstrdup(pw->pw_name);
1031 server_user = options.user ? options.user : local_user;
1033 /* Convert the user-supplied hostname into all lowercase. */
1034 host = xstrdup(orighost);
1035 for (cp = host; *cp; cp++)
1037 *cp = (char)tolower(*cp);
1039 /* Exchange protocol version identification strings with the server. */
1040 ssh_exchange_identification(timeout_ms);
1042 /* Put the connection into non-blocking mode. */
1043 packet_set_nonblocking();
1046 /* authenticate user */
1048 ssh_kex2(host, hostaddr);
1049 ssh_userauth2(local_user, server_user, host, sensitive);
1051 ssh_kex(host, hostaddr);
1052 ssh_userauth1(local_user, server_user, host, sensitive);
1058 ssh_put_password(char *password)
1063 if (datafellows & SSH_BUG_PASSWORDPAD) {
1064 packet_put_cstring(password);
1067 size = roundup(strlen(password) + 1, 32);
1068 padded = xcalloc(1, size);
1069 strlcpy(padded, password, size);
1070 packet_put_string(padded, size);
1071 memset(padded, 0, size);
1076 show_key_from_file(const char *file, const char *host, int keytype)
1082 found = key_new(keytype);
1083 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1084 keytype, found, &line))) {
1085 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1086 if (options.visual_host_key)
1087 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1088 logit("WARNING: %s key found for host %s\n"
1090 "%s key fingerprint %s.%s%s\n",
1091 key_type(found), host, file, line,
1092 key_type(found), fp,
1093 options.visual_host_key ? "\n" : "",
1094 options.visual_host_key ? ra : "");
1095 if (options.visual_host_key)
1103 /* print all known host keys for a given host, but skip keys of given type */
1105 show_other_keys(const char *host, Key *key)
1107 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1110 for (i = 0; type[i] != -1; i++) {
1111 if (type[i] == key->type)
1113 if (type[i] != KEY_RSA1 &&
1114 show_key_from_file(options.user_hostfile2, host, type[i])) {
1118 if (type[i] != KEY_RSA1 &&
1119 show_key_from_file(options.system_hostfile2, host, type[i])) {
1123 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1127 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1131 debug2("no key of type %d for host %s", type[i], host);
1137 warn_changed_key(Key *host_key)
1140 const char *type = key_type(host_key);
1142 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1144 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1145 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1146 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1147 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1148 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1149 error("It is also possible that the %s host key has just been changed.", type);
1150 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1152 error("Please contact your system administrator.");
1158 * Execute a local command
1161 ssh_local_cmd(const char *args)
1167 if (!options.permit_local_command ||
1168 args == NULL || !*args)
1171 if ((shell = getenv("SHELL")) == NULL)
1172 shell = _PATH_BSHELL;
1176 debug3("Executing %s -c \"%s\"", shell, args);
1177 execl(shell, shell, "-c", args, (char *)NULL);
1178 error("Couldn't execute %s -c \"%s\": %s",
1179 shell, args, strerror(errno));
1181 } else if (pid == -1)
1182 fatal("fork failed: %.100s", strerror(errno));
1183 while (waitpid(pid, &status, 0) == -1)
1185 fatal("Couldn't wait for child: %s", strerror(errno));
1187 if (!WIFEXITED(status))
1190 return (WEXITSTATUS(status));