1 /* $OpenBSD: sshconnect.c,v 1.212 2008/10/14 18:11:33 stevesk 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 static int show_other_keys(const char *, Key *);
75 static void warn_changed_key(Key *);
78 * Connect to the given ssh server using a proxy command.
81 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
83 char *command_string, *tmp;
86 char *shell, strport[NI_MAXSERV];
88 if ((shell = getenv("SHELL")) == NULL)
91 /* Convert the port number into a string. */
92 snprintf(strport, sizeof strport, "%hu", port);
95 * Build the final command string in the buffer by making the
96 * appropriate substitutions to the given proxy command.
98 * Use "exec" to avoid "sh -c" processes on some platforms
101 xasprintf(&tmp, "exec %s", proxy_command);
102 command_string = percent_expand(tmp, "h", host,
103 "p", strport, (char *)NULL);
106 /* Create pipes for communicating with the proxy. */
107 if (pipe(pin) < 0 || pipe(pout) < 0)
108 fatal("Could not create pipes to communicate with the proxy: %.100s",
111 debug("Executing proxy command: %.500s", command_string);
113 /* Fork and execute the proxy command. */
114 if ((pid = fork()) == 0) {
117 /* Child. Permanently give up superuser privileges. */
118 permanently_drop_suid(original_real_uid);
120 /* Redirect stdin and stdout. */
123 if (dup2(pin[0], 0) < 0)
124 perror("dup2 stdin");
128 if (dup2(pout[1], 1) < 0)
129 perror("dup2 stdout");
130 /* Cannot be 1 because pin allocated two descriptors. */
133 /* Stderr is left as it is so that error messages get
134 printed on the user's terminal. */
137 argv[2] = command_string;
140 /* Execute the proxy command. Note that we gave up any
141 extra privileges above. */
142 execv(argv[0], argv);
148 fatal("fork failed: %.100s", strerror(errno));
150 proxy_command_pid = pid; /* save pid to clean up later */
152 /* Close child side of the descriptors. */
156 /* Free the command name. */
157 xfree(command_string);
159 /* Set the connection file descriptors. */
160 packet_set_connection(pout[0], pin[1]);
161 packet_set_timeout(options.server_alive_interval,
162 options.server_alive_count_max);
164 /* Indicate OK return */
169 * Creates a (possibly privileged) socket for use as the ssh connection.
172 ssh_create_socket(int privileged, struct addrinfo *ai)
175 struct addrinfo hints, *res;
178 * If we are running as root and want to connect to a privileged
179 * port, bind our own socket to a privileged port.
182 int p = IPPORT_RESERVED - 1;
184 sock = rresvport_af(&p, ai->ai_family);
187 error("rresvport: af=%d %.100s", ai->ai_family,
190 debug("Allocated local port %d.", p);
193 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
195 error("socket: %.100s", strerror(errno));
197 /* Bind the socket to an alternative local IP address */
198 if (options.bind_address == NULL)
201 memset(&hints, 0, sizeof(hints));
202 hints.ai_family = ai->ai_family;
203 hints.ai_socktype = ai->ai_socktype;
204 hints.ai_protocol = ai->ai_protocol;
205 hints.ai_flags = AI_PASSIVE;
206 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
208 error("getaddrinfo: %s: %s", options.bind_address,
209 ssh_gai_strerror(gaierr));
213 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
214 error("bind: %s: %s", options.bind_address, strerror(errno));
224 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
225 socklen_t addrlen, int *timeoutp)
228 struct timeval tv, t_start;
230 int optval, rc, result = -1;
232 gettimeofday(&t_start, NULL);
234 if (*timeoutp <= 0) {
235 result = connect(sockfd, serv_addr, addrlen);
239 set_nonblock(sockfd);
240 rc = connect(sockfd, serv_addr, addrlen);
242 unset_nonblock(sockfd);
246 if (errno != EINPROGRESS) {
251 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
253 FD_SET(sockfd, fdset);
254 ms_to_timeval(&tv, *timeoutp);
257 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
258 if (rc != -1 || errno != EINTR)
269 debug("select: %s", strerror(errno));
272 /* Completed or failed */
274 optlen = sizeof(optval);
275 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
277 debug("getsockopt: %s", strerror(errno));
285 unset_nonblock(sockfd);
288 /* Should not occur */
289 fatal("Bogus return (%d) from select()", rc);
295 if (result == 0 && *timeoutp > 0) {
296 ms_subtract_diff(&t_start, timeoutp);
297 if (*timeoutp <= 0) {
307 * Opens a TCP/IP connection to the remote server on the given host.
308 * The address of the remote host will be returned in hostaddr.
309 * If port is 0, the default port will be used. If needpriv is true,
310 * a privileged port will be allocated to make the connection.
311 * This requires super-user privileges if needpriv is true.
312 * Connection_attempts specifies the maximum number of tries (one per
313 * second). If proxy_command is non-NULL, it specifies the command (with %h
314 * and %p substituted for host and port, respectively) to use to contact
318 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
319 u_short port, int family, int connection_attempts, int *timeout_ms,
320 int want_keepalive, int needpriv, const char *proxy_command)
324 int sock = -1, attempt;
325 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
326 struct addrinfo hints, *ai, *aitop;
328 debug2("ssh_connect: needpriv %d", needpriv);
330 /* If a proxy command is given, connect using it. */
331 if (proxy_command != NULL)
332 return ssh_proxy_connect(host, port, proxy_command);
334 /* No proxy command. */
336 memset(&hints, 0, sizeof(hints));
337 hints.ai_family = family;
338 hints.ai_socktype = SOCK_STREAM;
339 snprintf(strport, sizeof strport, "%u", port);
340 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
341 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
342 host, ssh_gai_strerror(gaierr));
344 for (attempt = 0; attempt < connection_attempts; attempt++) {
346 /* Sleep a moment before retrying. */
348 debug("Trying again...");
351 * Loop through addresses for this host, and try each one in
352 * sequence until the connection succeeds.
354 for (ai = aitop; ai; ai = ai->ai_next) {
355 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
357 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
358 ntop, sizeof(ntop), strport, sizeof(strport),
359 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
360 error("ssh_connect: getnameinfo failed");
363 debug("Connecting to %.200s [%.100s] port %s.",
364 host, ntop, strport);
366 /* Create a socket for connecting. */
367 sock = ssh_create_socket(needpriv, ai);
369 /* Any error is already output */
372 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
374 /* Successful connection. */
375 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
378 debug("connect to address %s port %s: %s",
379 ntop, strport, strerror(errno));
385 break; /* Successful connection. */
390 /* Return failure if we didn't get a successful connection. */
392 error("ssh: connect to host %s port %s: %s",
393 host, strport, strerror(errno));
397 debug("Connection established.");
399 /* Set SO_KEEPALIVE if requested. */
400 if (want_keepalive &&
401 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
403 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
405 /* Set the connection. */
406 packet_set_connection(sock, sock);
407 packet_set_timeout(options.server_alive_interval,
408 options.server_alive_count_max);
414 * Waits for the server identification string, and sends our own
415 * identification string.
418 ssh_exchange_identification(int timeout_ms)
420 char buf[256], remote_version[256]; /* must be same size! */
421 int remote_major, remote_minor, mismatch;
422 int connection_in = packet_get_connection_in();
423 int connection_out = packet_get_connection_out();
424 int minor1 = PROTOCOL_MINOR_1;
427 int fdsetsz, remaining, rc;
428 struct timeval t_start, t_remaining;
431 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
432 fdset = xcalloc(1, fdsetsz);
434 /* Read other side's version identification. */
435 remaining = timeout_ms;
437 for (i = 0; i < sizeof(buf) - 1; i++) {
438 if (timeout_ms > 0) {
439 gettimeofday(&t_start, NULL);
440 ms_to_timeval(&t_remaining, remaining);
441 FD_SET(connection_in, fdset);
442 rc = select(connection_in + 1, fdset, NULL,
443 fdset, &t_remaining);
444 ms_subtract_diff(&t_start, &remaining);
445 if (rc == 0 || remaining <= 0)
446 fatal("Connection timed out during "
451 fatal("ssh_exchange_identification: "
452 "select: %s", strerror(errno));
456 len = atomicio(read, connection_in, &buf[i], 1);
458 if (len != 1 && errno == EPIPE)
459 fatal("ssh_exchange_identification: "
460 "Connection closed by remote host");
462 fatal("ssh_exchange_identification: "
463 "read: %.100s", strerror(errno));
464 if (buf[i] == '\r') {
467 continue; /**XXX wait for \n */
469 if (buf[i] == '\n') {
474 fatal("ssh_exchange_identification: "
475 "No banner received");
477 buf[sizeof(buf) - 1] = 0;
478 if (strncmp(buf, "SSH-", 4) == 0)
480 debug("ssh_exchange_identification: %s", buf);
482 server_version_string = xstrdup(buf);
486 * Check that the versions match. In future this might accept
487 * several versions and set appropriate flags to handle them.
489 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
490 &remote_major, &remote_minor, remote_version) != 3)
491 fatal("Bad remote protocol version identification: '%.100s'", buf);
492 debug("Remote protocol version %d.%d, remote software version %.100s",
493 remote_major, remote_minor, remote_version);
495 compat_datafellows(remote_version);
498 switch (remote_major) {
500 if (remote_minor == 99 &&
501 (options.protocol & SSH_PROTO_2) &&
502 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
506 if (!(options.protocol & SSH_PROTO_1)) {
510 if (remote_minor < 3) {
511 fatal("Remote machine has too old SSH software version.");
512 } else if (remote_minor == 3 || remote_minor == 4) {
513 /* We speak 1.3, too. */
516 if (options.forward_agent) {
517 logit("Agent forwarding disabled for protocol 1.3");
518 options.forward_agent = 0;
523 if (options.protocol & SSH_PROTO_2) {
533 fatal("Protocol major versions differ: %d vs. %d",
534 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
536 /* Send our own protocol version identification. */
537 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
538 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
539 compat20 ? PROTOCOL_MINOR_2 : minor1,
540 SSH_VERSION, compat20 ? "\r\n" : "\n");
541 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
542 fatal("write: %.100s", strerror(errno));
543 client_version_string = xstrdup(buf);
544 chop(client_version_string);
545 chop(server_version_string);
546 debug("Local version string %.100s", client_version_string);
549 /* defaults to 'no' */
551 confirm(const char *prompt)
553 const char *msg, *again = "Please type 'yes' or 'no': ";
557 if (options.batch_mode)
559 for (msg = prompt;;msg = again) {
560 p = read_passphrase(msg, RP_ECHO);
562 (p[0] == '\0') || (p[0] == '\n') ||
563 strncasecmp(p, "no", 2) == 0)
565 if (p && strncasecmp(p, "yes", 3) == 0)
575 * check whether the supplied host key is valid, return -1 if the key
576 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
582 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
583 Key *host_key, int readonly, const char *user_hostfile,
584 const char *system_hostfile)
587 const char *type = key_type(host_key);
588 char *ip = NULL, *host = NULL;
589 char hostline[1000], *hostp, *fp, *ra;
590 HostStatus host_status;
591 HostStatus ip_status;
592 int r, local = 0, host_ip_differ = 0;
594 char ntop[NI_MAXHOST];
596 int len, host_line, ip_line, cancelled_forwarding = 0;
597 const char *host_file = NULL, *ip_file = NULL;
600 * Force accepting of the host key for loopback/localhost. The
601 * problem is that if the home directory is NFS-mounted to multiple
602 * machines, localhost will refer to a different machine in each of
603 * them, and the user will get bogus HOST_CHANGED warnings. This
604 * essentially disables host authentication for localhost; however,
605 * this is probably not a real problem.
607 /** hostaddr == 0! */
608 switch (hostaddr->sa_family) {
610 local = (ntohl(((struct sockaddr_in *)hostaddr)->
611 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
612 salen = sizeof(struct sockaddr_in);
615 local = IN6_IS_ADDR_LOOPBACK(
616 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
617 salen = sizeof(struct sockaddr_in6);
621 salen = sizeof(struct sockaddr_storage);
624 if (options.no_host_authentication_for_localhost == 1 && local &&
625 options.host_key_alias == NULL) {
626 debug("Forcing accepting of host key for "
627 "loopback/localhost.");
632 * We don't have the remote ip-address for connections
633 * using a proxy command
635 if (options.proxy_command == NULL) {
636 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
637 NULL, 0, NI_NUMERICHOST) != 0)
638 fatal("check_host_key: getnameinfo failed");
639 ip = put_host_port(ntop, port);
641 ip = xstrdup("<no hostip for proxy command>");
645 * Turn off check_host_ip if the connection is to localhost, via proxy
646 * command or if we don't have a hostname to compare with
648 if (options.check_host_ip && (local ||
649 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
650 options.check_host_ip = 0;
653 * Allow the user to record the key under a different name or
654 * differentiate a non-standard port. This is useful for ssh
655 * tunneling over forwarded connections or if you run multiple
656 * sshd's on different ports on the same machine.
658 if (options.host_key_alias != NULL) {
659 host = xstrdup(options.host_key_alias);
660 debug("using hostkeyalias: %s", host);
662 host = put_host_port(hostname, port);
666 * Store the host key from the known host file in here so that we can
667 * compare it with the key for the IP address.
669 file_key = key_new(host_key->type);
672 * Check if the host key is present in the user's list of known
673 * hosts or in the systemwide list.
675 host_file = user_hostfile;
676 host_status = check_host_in_hostfile(host_file, host, host_key,
677 file_key, &host_line);
678 if (host_status == HOST_NEW) {
679 host_file = system_hostfile;
680 host_status = check_host_in_hostfile(host_file, host, host_key,
681 file_key, &host_line);
684 * Also perform check for the ip address, skip the check if we are
685 * localhost or the hostname was an ip address to begin with
687 if (options.check_host_ip) {
688 Key *ip_key = key_new(host_key->type);
690 ip_file = user_hostfile;
691 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
693 if (ip_status == HOST_NEW) {
694 ip_file = system_hostfile;
695 ip_status = check_host_in_hostfile(ip_file, ip,
696 host_key, ip_key, &ip_line);
698 if (host_status == HOST_CHANGED &&
699 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
704 ip_status = host_status;
708 switch (host_status) {
710 /* The host is known and the key matches. */
711 debug("Host '%.200s' is known and matches the %s host key.",
713 debug("Found key in %s:%d", host_file, host_line);
714 if (options.check_host_ip && ip_status == HOST_NEW) {
716 logit("%s host key for IP address "
717 "'%.128s' not in list of known hosts.",
719 else if (!add_host_to_hostfile(user_hostfile, ip,
720 host_key, options.hash_known_hosts))
721 logit("Failed to add the %s host key for IP "
722 "address '%.128s' to the list of known "
723 "hosts (%.30s).", type, ip, user_hostfile);
725 logit("Warning: Permanently added the %s host "
726 "key for IP address '%.128s' to the list "
727 "of known hosts.", type, ip);
728 } else if (options.visual_host_key) {
729 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
730 ra = key_fingerprint(host_key, SSH_FP_MD5,
732 logit("Host key fingerprint is %s\n%s\n", fp, ra);
738 if (options.host_key_alias == NULL && port != 0 &&
739 port != SSH_DEFAULT_PORT) {
740 debug("checking without port identifier");
741 if (check_host_key(hostname, hostaddr, 0, host_key,
742 ROQUIET, user_hostfile, system_hostfile) == 0) {
743 debug("found matching key w/out port");
749 /* The host is new. */
750 if (options.strict_host_key_checking == 1) {
752 * User has requested strict host key checking. We
753 * will not add the host key automatically. The only
754 * alternative left is to abort.
756 error("No %s host key is known for %.200s and you "
757 "have requested strict checking.", type, host);
759 } else if (options.strict_host_key_checking == 2) {
760 char msg1[1024], msg2[1024];
762 if (show_other_keys(host, host_key))
763 snprintf(msg1, sizeof(msg1),
764 "\nbut keys of different type are already"
765 " known for this host.");
767 snprintf(msg1, sizeof(msg1), ".");
769 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
770 ra = key_fingerprint(host_key, SSH_FP_MD5,
773 if (options.verify_host_key_dns) {
774 if (matching_host_key_dns)
775 snprintf(msg2, sizeof(msg2),
776 "Matching host key fingerprint"
779 snprintf(msg2, sizeof(msg2),
780 "No matching host key fingerprint"
783 snprintf(msg, sizeof(msg),
784 "The authenticity of host '%.200s (%s)' can't be "
786 "%s key fingerprint is %s.%s%s\n%s"
787 "Are you sure you want to continue connecting "
789 host, ip, msg1, type, fp,
790 options.visual_host_key ? "\n" : "",
791 options.visual_host_key ? ra : "",
799 * If not in strict mode, add the key automatically to the
800 * local known_hosts file.
802 if (options.check_host_ip && ip_status == HOST_NEW) {
803 snprintf(hostline, sizeof(hostline), "%s,%s",
806 if (options.hash_known_hosts) {
807 /* Add hash of host and IP separately */
808 r = add_host_to_hostfile(user_hostfile, host,
809 host_key, options.hash_known_hosts) &&
810 add_host_to_hostfile(user_hostfile, ip,
811 host_key, options.hash_known_hosts);
813 /* Add unhashed "host,ip" */
814 r = add_host_to_hostfile(user_hostfile,
816 options.hash_known_hosts);
819 r = add_host_to_hostfile(user_hostfile, host, host_key,
820 options.hash_known_hosts);
825 logit("Failed to add the host to the list of known "
826 "hosts (%.500s).", user_hostfile);
828 logit("Warning: Permanently added '%.200s' (%s) to the "
829 "list of known hosts.", hostp, type);
832 if (readonly == ROQUIET)
834 if (options.check_host_ip && host_ip_differ) {
836 if (ip_status == HOST_NEW)
837 key_msg = "is unknown";
838 else if (ip_status == HOST_OK)
839 key_msg = "is unchanged";
841 key_msg = "has a different value";
842 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
843 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
844 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
845 error("The %s host key for %s has changed,", type, host);
846 error("and the key for the corresponding IP address %s", ip);
847 error("%s. This could either mean that", key_msg);
848 error("DNS SPOOFING is happening or the IP address for the host");
849 error("and its host key have changed at the same time.");
850 if (ip_status != HOST_NEW)
851 error("Offending key for IP in %s:%d", ip_file, ip_line);
853 /* The host key has changed. */
854 warn_changed_key(host_key);
855 error("Add correct host key in %.100s to get rid of this message.",
857 error("Offending key in %s:%d", host_file, host_line);
860 * If strict host key checking is in use, the user will have
861 * to edit the key manually and we can only abort.
863 if (options.strict_host_key_checking) {
864 error("%s host key for %.200s has changed and you have "
865 "requested strict checking.", type, host);
870 * If strict host key checking has not been requested, allow
871 * the connection but without MITM-able authentication or
874 if (options.password_authentication) {
875 error("Password authentication is disabled to avoid "
876 "man-in-the-middle attacks.");
877 options.password_authentication = 0;
878 cancelled_forwarding = 1;
880 if (options.kbd_interactive_authentication) {
881 error("Keyboard-interactive authentication is disabled"
882 " to avoid man-in-the-middle attacks.");
883 options.kbd_interactive_authentication = 0;
884 options.challenge_response_authentication = 0;
885 cancelled_forwarding = 1;
887 if (options.challenge_response_authentication) {
888 error("Challenge/response authentication is disabled"
889 " to avoid man-in-the-middle attacks.");
890 options.challenge_response_authentication = 0;
891 cancelled_forwarding = 1;
893 if (options.forward_agent) {
894 error("Agent forwarding is disabled to avoid "
895 "man-in-the-middle attacks.");
896 options.forward_agent = 0;
897 cancelled_forwarding = 1;
899 if (options.forward_x11) {
900 error("X11 forwarding is disabled to avoid "
901 "man-in-the-middle attacks.");
902 options.forward_x11 = 0;
903 cancelled_forwarding = 1;
905 if (options.num_local_forwards > 0 ||
906 options.num_remote_forwards > 0) {
907 error("Port forwarding is disabled to avoid "
908 "man-in-the-middle attacks.");
909 options.num_local_forwards =
910 options.num_remote_forwards = 0;
911 cancelled_forwarding = 1;
913 if (options.tun_open != SSH_TUNMODE_NO) {
914 error("Tunnel forwarding is disabled to avoid "
915 "man-in-the-middle attacks.");
916 options.tun_open = SSH_TUNMODE_NO;
917 cancelled_forwarding = 1;
919 if (options.exit_on_forward_failure && cancelled_forwarding)
920 fatal("Error: forwarding disabled due to host key "
924 * XXX Should permit the user to change to use the new id.
925 * This could be done by converting the host key to an
926 * identifying sentence, tell that the host identifies itself
927 * by that sentence, and ask the user if he/she whishes to
928 * accept the authentication.
932 fatal("internal error");
936 if (options.check_host_ip && host_status != HOST_CHANGED &&
937 ip_status == HOST_CHANGED) {
938 snprintf(msg, sizeof(msg),
939 "Warning: the %s host key for '%.200s' "
940 "differs from the key for the IP address '%.128s'"
941 "\nOffending key for IP in %s:%d",
942 type, host, ip, ip_file, ip_line);
943 if (host_status == HOST_OK) {
945 snprintf(msg + len, sizeof(msg) - len,
946 "\nMatching host key in %s:%d",
947 host_file, host_line);
949 if (options.strict_host_key_checking == 1) {
951 error("Exiting, you have requested strict checking.");
953 } else if (options.strict_host_key_checking == 2) {
954 strlcat(msg, "\nAre you sure you want "
955 "to continue connecting (yes/no)? ", sizeof(msg));
973 /* returns 0 if key verifies or -1 if key does NOT verify */
975 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
980 if (options.verify_host_key_dns &&
981 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
983 if (flags & DNS_VERIFY_FOUND) {
985 if (options.verify_host_key_dns == 1 &&
986 flags & DNS_VERIFY_MATCH &&
987 flags & DNS_VERIFY_SECURE)
990 if (flags & DNS_VERIFY_MATCH) {
991 matching_host_key_dns = 1;
993 warn_changed_key(host_key);
994 error("Update the SSHFP RR in DNS with the new "
995 "host key to get rid of this message.");
1000 /* return ok if the key can be found in an old keyfile */
1001 if (stat(options.system_hostfile2, &st) == 0 ||
1002 stat(options.user_hostfile2, &st) == 0) {
1003 if (check_host_key(host, hostaddr, options.port, host_key,
1004 RDONLY, options.user_hostfile2,
1005 options.system_hostfile2) == 0)
1008 return check_host_key(host, hostaddr, options.port, host_key,
1009 RDRW, options.user_hostfile, options.system_hostfile);
1013 * Starts a dialog with the server, and authenticates the current user on the
1014 * server. This does not need any extra privileges. The basic connection
1015 * to the server must already have been established before this is called.
1016 * If login fails, this function prints an error and never returns.
1017 * This function does not require super-user privileges.
1020 ssh_login(Sensitive *sensitive, const char *orighost,
1021 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1024 char *server_user, *local_user;
1026 local_user = xstrdup(pw->pw_name);
1027 server_user = options.user ? options.user : local_user;
1029 /* Convert the user-supplied hostname into all lowercase. */
1030 host = xstrdup(orighost);
1031 for (cp = host; *cp; cp++)
1033 *cp = (char)tolower(*cp);
1035 /* Exchange protocol version identification strings with the server. */
1036 ssh_exchange_identification(timeout_ms);
1038 /* Put the connection into non-blocking mode. */
1039 packet_set_nonblocking();
1042 /* authenticate user */
1044 ssh_kex2(host, hostaddr);
1045 ssh_userauth2(local_user, server_user, host, sensitive);
1047 ssh_kex(host, hostaddr);
1048 ssh_userauth1(local_user, server_user, host, sensitive);
1054 ssh_put_password(char *password)
1059 if (datafellows & SSH_BUG_PASSWORDPAD) {
1060 packet_put_cstring(password);
1063 size = roundup(strlen(password) + 1, 32);
1064 padded = xcalloc(1, size);
1065 strlcpy(padded, password, size);
1066 packet_put_string(padded, size);
1067 memset(padded, 0, size);
1072 show_key_from_file(const char *file, const char *host, int keytype)
1078 found = key_new(keytype);
1079 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1080 keytype, found, &line))) {
1081 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1082 if (options.visual_host_key)
1083 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1084 logit("WARNING: %s key found for host %s\n"
1086 "%s key fingerprint %s.%s%s\n",
1087 key_type(found), host, file, line,
1088 key_type(found), fp,
1089 options.visual_host_key ? "\n" : "",
1090 options.visual_host_key ? ra : "");
1091 if (options.visual_host_key)
1099 /* print all known host keys for a given host, but skip keys of given type */
1101 show_other_keys(const char *host, Key *key)
1103 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1106 for (i = 0; type[i] != -1; i++) {
1107 if (type[i] == key->type)
1109 if (type[i] != KEY_RSA1 &&
1110 show_key_from_file(options.user_hostfile2, host, type[i])) {
1114 if (type[i] != KEY_RSA1 &&
1115 show_key_from_file(options.system_hostfile2, host, type[i])) {
1119 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1123 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1127 debug2("no key of type %d for host %s", type[i], host);
1133 warn_changed_key(Key *host_key)
1136 const char *type = key_type(host_key);
1138 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1140 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1141 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1142 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1143 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1144 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1145 error("It is also possible that the %s host key has just been changed.", type);
1146 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1148 error("Please contact your system administrator.");
1154 * Execute a local command
1157 ssh_local_cmd(const char *args)
1163 if (!options.permit_local_command ||
1164 args == NULL || !*args)
1167 if ((shell = getenv("SHELL")) == NULL)
1168 shell = _PATH_BSHELL;
1172 debug3("Executing %s -c \"%s\"", shell, args);
1173 execl(shell, shell, "-c", args, (char *)NULL);
1174 error("Couldn't execute %s -c \"%s\": %s",
1175 shell, args, strerror(errno));
1177 } else if (pid == -1)
1178 fatal("fork failed: %.100s", strerror(errno));
1179 while (waitpid(pid, &status, 0) == -1)
1181 fatal("Couldn't wait for child: %s", strerror(errno));
1183 if (!WIFEXITED(status))
1186 return (WEXITSTATUS(status));