1 /* $OpenBSD: sshconnect.c,v 1.206 2008/06/12 00:13:55 grunk 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 #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
74 #define INET6_ADDRSTRLEN 46
77 static int show_other_keys(const char *, Key *);
78 static void warn_changed_key(Key *);
81 ms_subtract_diff(struct timeval *start, int *ms)
83 struct timeval diff, finish;
85 gettimeofday(&finish, NULL);
86 timersub(&finish, start, &diff);
87 *ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000);
91 ms_to_timeval(struct timeval *tv, int ms)
93 tv->tv_sec = ms / 1000;
94 tv->tv_usec = (ms % 1000) * 1000;
98 * Connect to the given ssh server using a proxy command.
101 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
103 char *command_string, *tmp;
106 char *shell, strport[NI_MAXSERV];
108 if ((shell = getenv("SHELL")) == NULL)
109 shell = _PATH_BSHELL;
111 /* Convert the port number into a string. */
112 snprintf(strport, sizeof strport, "%hu", port);
115 * Build the final command string in the buffer by making the
116 * appropriate substitutions to the given proxy command.
118 * Use "exec" to avoid "sh -c" processes on some platforms
121 xasprintf(&tmp, "exec %s", proxy_command);
122 command_string = percent_expand(tmp, "h", host,
123 "p", strport, (char *)NULL);
126 /* Create pipes for communicating with the proxy. */
127 if (pipe(pin) < 0 || pipe(pout) < 0)
128 fatal("Could not create pipes to communicate with the proxy: %.100s",
131 debug("Executing proxy command: %.500s", command_string);
133 /* Fork and execute the proxy command. */
134 if ((pid = fork()) == 0) {
137 /* Child. Permanently give up superuser privileges. */
138 permanently_drop_suid(original_real_uid);
140 /* Redirect stdin and stdout. */
143 if (dup2(pin[0], 0) < 0)
144 perror("dup2 stdin");
148 if (dup2(pout[1], 1) < 0)
149 perror("dup2 stdout");
150 /* Cannot be 1 because pin allocated two descriptors. */
153 /* Stderr is left as it is so that error messages get
154 printed on the user's terminal. */
157 argv[2] = command_string;
160 /* Execute the proxy command. Note that we gave up any
161 extra privileges above. */
162 execv(argv[0], argv);
168 fatal("fork failed: %.100s", strerror(errno));
170 proxy_command_pid = pid; /* save pid to clean up later */
172 /* Close child side of the descriptors. */
176 /* Free the command name. */
177 xfree(command_string);
179 /* Set the connection file descriptors. */
180 packet_set_connection(pout[0], pin[1]);
182 /* Indicate OK return */
187 * Creates a (possibly privileged) socket for use as the ssh connection.
190 ssh_create_socket(int privileged, struct addrinfo *ai)
193 struct addrinfo hints, *res;
196 * If we are running as root and want to connect to a privileged
197 * port, bind our own socket to a privileged port.
200 int p = IPPORT_RESERVED - 1;
202 sock = rresvport_af(&p, ai->ai_family);
205 error("rresvport: af=%d %.100s", ai->ai_family,
208 debug("Allocated local port %d.", p);
211 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
213 error("socket: %.100s", strerror(errno));
215 /* Bind the socket to an alternative local IP address */
216 if (options.bind_address == NULL)
219 memset(&hints, 0, sizeof(hints));
220 hints.ai_family = ai->ai_family;
221 hints.ai_socktype = ai->ai_socktype;
222 hints.ai_protocol = ai->ai_protocol;
223 hints.ai_flags = AI_PASSIVE;
224 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
226 error("getaddrinfo: %s: %s", options.bind_address,
227 ssh_gai_strerror(gaierr));
231 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
232 error("bind: %s: %s", options.bind_address, strerror(errno));
242 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
243 socklen_t addrlen, int *timeoutp)
246 struct timeval tv, t_start;
248 int optval, rc, result = -1;
250 gettimeofday(&t_start, NULL);
252 if (*timeoutp <= 0) {
253 result = connect(sockfd, serv_addr, addrlen);
257 set_nonblock(sockfd);
258 rc = connect(sockfd, serv_addr, addrlen);
260 unset_nonblock(sockfd);
264 if (errno != EINPROGRESS) {
269 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
271 FD_SET(sockfd, fdset);
272 ms_to_timeval(&tv, *timeoutp);
275 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
276 if (rc != -1 || errno != EINTR)
287 debug("select: %s", strerror(errno));
290 /* Completed or failed */
292 optlen = sizeof(optval);
293 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
295 debug("getsockopt: %s", strerror(errno));
303 unset_nonblock(sockfd);
306 /* Should not occur */
307 fatal("Bogus return (%d) from select()", rc);
313 if (result == 0 && *timeoutp > 0) {
314 ms_subtract_diff(&t_start, timeoutp);
315 if (*timeoutp <= 0) {
325 * Opens a TCP/IP connection to the remote server on the given host.
326 * The address of the remote host will be returned in hostaddr.
327 * If port is 0, the default port will be used. If needpriv is true,
328 * a privileged port will be allocated to make the connection.
329 * This requires super-user privileges if needpriv is true.
330 * Connection_attempts specifies the maximum number of tries (one per
331 * second). If proxy_command is non-NULL, it specifies the command (with %h
332 * and %p substituted for host and port, respectively) to use to contact
336 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
337 u_short port, int family, int connection_attempts, int *timeout_ms,
338 int want_keepalive, int needpriv, const char *proxy_command)
342 int sock = -1, attempt;
343 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
344 struct addrinfo hints, *ai, *aitop;
346 debug2("ssh_connect: needpriv %d", needpriv);
348 /* If a proxy command is given, connect using it. */
349 if (proxy_command != NULL)
350 return ssh_proxy_connect(host, port, proxy_command);
352 /* No proxy command. */
354 memset(&hints, 0, sizeof(hints));
355 hints.ai_family = family;
356 hints.ai_socktype = SOCK_STREAM;
357 snprintf(strport, sizeof strport, "%u", port);
358 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
359 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
360 host, ssh_gai_strerror(gaierr));
362 for (attempt = 0; attempt < connection_attempts; attempt++) {
364 /* Sleep a moment before retrying. */
366 debug("Trying again...");
369 * Loop through addresses for this host, and try each one in
370 * sequence until the connection succeeds.
372 for (ai = aitop; ai; ai = ai->ai_next) {
373 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
375 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
376 ntop, sizeof(ntop), strport, sizeof(strport),
377 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
378 error("ssh_connect: getnameinfo failed");
381 debug("Connecting to %.200s [%.100s] port %s.",
382 host, ntop, strport);
384 /* Create a socket for connecting. */
385 sock = ssh_create_socket(needpriv, ai);
387 /* Any error is already output */
390 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
392 /* Successful connection. */
393 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
396 debug("connect to address %s port %s: %s",
397 ntop, strport, strerror(errno));
403 break; /* Successful connection. */
408 /* Return failure if we didn't get a successful connection. */
410 error("ssh: connect to host %s port %s: %s",
411 host, strport, strerror(errno));
415 debug("Connection established.");
417 /* Set SO_KEEPALIVE if requested. */
418 if (want_keepalive &&
419 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
421 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
423 /* Set the connection. */
424 packet_set_connection(sock, sock);
430 * Waits for the server identification string, and sends our own
431 * identification string.
434 ssh_exchange_identification(int timeout_ms)
436 char buf[256], remote_version[256]; /* must be same size! */
437 int remote_major, remote_minor, mismatch;
438 int connection_in = packet_get_connection_in();
439 int connection_out = packet_get_connection_out();
440 int minor1 = PROTOCOL_MINOR_1;
443 int fdsetsz, remaining, rc;
444 struct timeval t_start, t_remaining;
447 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
448 fdset = xcalloc(1, fdsetsz);
450 /* Read other side's version identification. */
451 remaining = timeout_ms;
453 for (i = 0; i < sizeof(buf) - 1; i++) {
454 if (timeout_ms > 0) {
455 gettimeofday(&t_start, NULL);
456 ms_to_timeval(&t_remaining, remaining);
457 FD_SET(connection_in, fdset);
458 rc = select(connection_in + 1, fdset, NULL,
459 fdset, &t_remaining);
460 ms_subtract_diff(&t_start, &remaining);
461 if (rc == 0 || remaining <= 0)
462 fatal("Connection timed out during "
467 fatal("ssh_exchange_identification: "
468 "select: %s", strerror(errno));
472 len = atomicio(read, connection_in, &buf[i], 1);
474 if (len != 1 && errno == EPIPE)
475 fatal("ssh_exchange_identification: "
476 "Connection closed by remote host");
478 fatal("ssh_exchange_identification: "
479 "read: %.100s", strerror(errno));
480 if (buf[i] == '\r') {
483 continue; /**XXX wait for \n */
485 if (buf[i] == '\n') {
490 fatal("ssh_exchange_identification: "
491 "No banner received");
493 buf[sizeof(buf) - 1] = 0;
494 if (strncmp(buf, "SSH-", 4) == 0)
496 debug("ssh_exchange_identification: %s", buf);
498 server_version_string = xstrdup(buf);
502 * Check that the versions match. In future this might accept
503 * several versions and set appropriate flags to handle them.
505 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
506 &remote_major, &remote_minor, remote_version) != 3)
507 fatal("Bad remote protocol version identification: '%.100s'", buf);
508 debug("Remote protocol version %d.%d, remote software version %.100s",
509 remote_major, remote_minor, remote_version);
511 compat_datafellows(remote_version);
514 switch (remote_major) {
516 if (remote_minor == 99 &&
517 (options.protocol & SSH_PROTO_2) &&
518 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
522 if (!(options.protocol & SSH_PROTO_1)) {
526 if (remote_minor < 3) {
527 fatal("Remote machine has too old SSH software version.");
528 } else if (remote_minor == 3 || remote_minor == 4) {
529 /* We speak 1.3, too. */
532 if (options.forward_agent) {
533 logit("Agent forwarding disabled for protocol 1.3");
534 options.forward_agent = 0;
539 if (options.protocol & SSH_PROTO_2) {
549 fatal("Protocol major versions differ: %d vs. %d",
550 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
552 /* Send our own protocol version identification. */
553 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
554 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
555 compat20 ? PROTOCOL_MINOR_2 : minor1,
557 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
558 fatal("write: %.100s", strerror(errno));
559 client_version_string = xstrdup(buf);
560 chop(client_version_string);
561 chop(server_version_string);
562 debug("Local version string %.100s", client_version_string);
565 /* defaults to 'no' */
567 confirm(const char *prompt)
569 const char *msg, *again = "Please type 'yes' or 'no': ";
573 if (options.batch_mode)
575 for (msg = prompt;;msg = again) {
576 p = read_passphrase(msg, RP_ECHO);
578 (p[0] == '\0') || (p[0] == '\n') ||
579 strncasecmp(p, "no", 2) == 0)
581 if (p && strncasecmp(p, "yes", 3) == 0)
591 * check whether the supplied host key is valid, return -1 if the key
592 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
598 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
599 Key *host_key, int readonly, const char *user_hostfile,
600 const char *system_hostfile)
603 const char *type = key_type(host_key);
604 char *ip = NULL, *host = NULL;
605 char hostline[1000], *hostp, *fp, *ra;
606 HostStatus host_status;
607 HostStatus ip_status;
608 int r, local = 0, host_ip_differ = 0;
610 char ntop[NI_MAXHOST];
612 int len, host_line, ip_line;
613 const char *host_file = NULL, *ip_file = NULL;
614 int display_randomart;
617 * Force accepting of the host key for loopback/localhost. The
618 * problem is that if the home directory is NFS-mounted to multiple
619 * machines, localhost will refer to a different machine in each of
620 * them, and the user will get bogus HOST_CHANGED warnings. This
621 * essentially disables host authentication for localhost; however,
622 * this is probably not a real problem.
624 /** hostaddr == 0! */
625 switch (hostaddr->sa_family) {
627 local = (ntohl(((struct sockaddr_in *)hostaddr)->
628 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
629 salen = sizeof(struct sockaddr_in);
632 local = IN6_IS_ADDR_LOOPBACK(
633 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
634 salen = sizeof(struct sockaddr_in6);
638 salen = sizeof(struct sockaddr_storage);
641 if (options.no_host_authentication_for_localhost == 1 && local &&
642 options.host_key_alias == NULL) {
643 debug("Forcing accepting of host key for "
644 "loopback/localhost.");
649 * We don't have the remote ip-address for connections
650 * using a proxy command
652 if (options.proxy_command == NULL) {
653 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
654 NULL, 0, NI_NUMERICHOST) != 0)
655 fatal("check_host_key: getnameinfo failed");
656 ip = put_host_port(ntop, port);
658 ip = xstrdup("<no hostip for proxy command>");
662 * check_host_ip may be set to zero in the next step, so if it
663 * conveys a request to display the random art, save it away.
665 display_randomart = (options.check_host_ip == SSHCTL_CHECKHOSTIP_FPR);
668 * Turn off check_host_ip if the connection is to localhost, via proxy
669 * command or if we don't have a hostname to compare with
671 if (options.check_host_ip && (local ||
672 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
673 options.check_host_ip = 0;
676 * Allow the user to record the key under a different name or
677 * differentiate a non-standard port. This is useful for ssh
678 * tunneling over forwarded connections or if you run multiple
679 * sshd's on different ports on the same machine.
681 if (options.host_key_alias != NULL) {
682 host = xstrdup(options.host_key_alias);
683 debug("using hostkeyalias: %s", host);
685 host = put_host_port(hostname, port);
689 * Store the host key from the known host file in here so that we can
690 * compare it with the key for the IP address.
692 file_key = key_new(host_key->type);
695 * Check if the host key is present in the user's list of known
696 * hosts or in the systemwide list.
698 host_file = user_hostfile;
699 host_status = check_host_in_hostfile(host_file, host, host_key,
700 file_key, &host_line);
701 if (host_status == HOST_NEW) {
702 host_file = system_hostfile;
703 host_status = check_host_in_hostfile(host_file, host, host_key,
704 file_key, &host_line);
707 * Also perform check for the ip address, skip the check if we are
708 * localhost or the hostname was an ip address to begin with
710 if (options.check_host_ip) {
711 Key *ip_key = key_new(host_key->type);
713 ip_file = user_hostfile;
714 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
716 if (ip_status == HOST_NEW) {
717 ip_file = system_hostfile;
718 ip_status = check_host_in_hostfile(ip_file, ip,
719 host_key, ip_key, &ip_line);
721 if (host_status == HOST_CHANGED &&
722 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
727 ip_status = host_status;
731 switch (host_status) {
733 /* The host is known and the key matches. */
734 debug("Host '%.200s' is known and matches the %s host key.",
736 debug("Found key in %s:%d", host_file, host_line);
737 if (options.check_host_ip && ip_status == HOST_NEW) {
739 logit("%s host key for IP address "
740 "'%.128s' not in list of known hosts.",
742 else if (!add_host_to_hostfile(user_hostfile, ip,
743 host_key, options.hash_known_hosts))
744 logit("Failed to add the %s host key for IP "
745 "address '%.128s' to the list of known "
746 "hosts (%.30s).", type, ip, user_hostfile);
748 logit("Warning: Permanently added the %s host "
749 "key for IP address '%.128s' to the list "
750 "of known hosts.", type, ip);
751 } else if (display_randomart) {
752 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
753 ra = key_fingerprint(host_key, SSH_FP_MD5,
755 logit("Host key fingerprint is %s\n%s\n", fp, ra);
761 if (options.host_key_alias == NULL && port != 0 &&
762 port != SSH_DEFAULT_PORT) {
763 debug("checking without port identifier");
764 if (check_host_key(hostname, hostaddr, 0, host_key, 2,
765 user_hostfile, system_hostfile) == 0) {
766 debug("found matching key w/out port");
772 /* The host is new. */
773 if (options.strict_host_key_checking == 1) {
775 * User has requested strict host key checking. We
776 * will not add the host key automatically. The only
777 * alternative left is to abort.
779 error("No %s host key is known for %.200s and you "
780 "have requested strict checking.", type, host);
782 } else if (options.strict_host_key_checking == 2) {
783 char msg1[1024], msg2[1024];
785 if (show_other_keys(host, host_key))
786 snprintf(msg1, sizeof(msg1),
787 "\nbut keys of different type are already"
788 " known for this host.");
790 snprintf(msg1, sizeof(msg1), ".");
792 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
793 ra = key_fingerprint(host_key, SSH_FP_MD5,
796 if (options.verify_host_key_dns) {
797 if (matching_host_key_dns)
798 snprintf(msg2, sizeof(msg2),
799 "Matching host key fingerprint"
802 snprintf(msg2, sizeof(msg2),
803 "No matching host key fingerprint"
806 snprintf(msg, sizeof(msg),
807 "The authenticity of host '%.200s (%s)' can't be "
809 "%s key fingerprint is %s.\n%s\n%s"
810 "Are you sure you want to continue connecting "
812 host, ip, msg1, type, fp, ra, msg2);
819 * If not in strict mode, add the key automatically to the
820 * local known_hosts file.
822 if (options.check_host_ip && ip_status == HOST_NEW) {
823 snprintf(hostline, sizeof(hostline), "%s,%s",
826 if (options.hash_known_hosts) {
827 /* Add hash of host and IP separately */
828 r = add_host_to_hostfile(user_hostfile, host,
829 host_key, options.hash_known_hosts) &&
830 add_host_to_hostfile(user_hostfile, ip,
831 host_key, options.hash_known_hosts);
833 /* Add unhashed "host,ip" */
834 r = add_host_to_hostfile(user_hostfile,
836 options.hash_known_hosts);
839 r = add_host_to_hostfile(user_hostfile, host, host_key,
840 options.hash_known_hosts);
845 logit("Failed to add the host to the list of known "
846 "hosts (%.500s).", user_hostfile);
848 logit("Warning: Permanently added '%.200s' (%s) to the "
849 "list of known hosts.", hostp, type);
852 if (readonly == ROQUIET)
854 if (options.check_host_ip && host_ip_differ) {
856 if (ip_status == HOST_NEW)
857 key_msg = "is unknown";
858 else if (ip_status == HOST_OK)
859 key_msg = "is unchanged";
861 key_msg = "has a different value";
862 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
863 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
864 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
865 error("The %s host key for %s has changed,", type, host);
866 error("and the key for the according IP address %s", ip);
867 error("%s. This could either mean that", key_msg);
868 error("DNS SPOOFING is happening or the IP address for the host");
869 error("and its host key have changed at the same time.");
870 if (ip_status != HOST_NEW)
871 error("Offending key for IP in %s:%d", ip_file, ip_line);
873 /* The host key has changed. */
874 warn_changed_key(host_key);
875 error("Add correct host key in %.100s to get rid of this message.",
877 error("Offending key in %s:%d", host_file, host_line);
880 * If strict host key checking is in use, the user will have
881 * to edit the key manually and we can only abort.
883 if (options.strict_host_key_checking) {
884 error("%s host key for %.200s has changed and you have "
885 "requested strict checking.", type, host);
890 * If strict host key checking has not been requested, allow
891 * the connection but without MITM-able authentication or
894 if (options.password_authentication) {
895 error("Password authentication is disabled to avoid "
896 "man-in-the-middle attacks.");
897 options.password_authentication = 0;
899 if (options.kbd_interactive_authentication) {
900 error("Keyboard-interactive authentication is disabled"
901 " to avoid man-in-the-middle attacks.");
902 options.kbd_interactive_authentication = 0;
903 options.challenge_response_authentication = 0;
905 if (options.challenge_response_authentication) {
906 error("Challenge/response authentication is disabled"
907 " to avoid man-in-the-middle attacks.");
908 options.challenge_response_authentication = 0;
910 if (options.forward_agent) {
911 error("Agent forwarding is disabled to avoid "
912 "man-in-the-middle attacks.");
913 options.forward_agent = 0;
915 if (options.forward_x11) {
916 error("X11 forwarding is disabled to avoid "
917 "man-in-the-middle attacks.");
918 options.forward_x11 = 0;
920 if (options.num_local_forwards > 0 ||
921 options.num_remote_forwards > 0) {
922 error("Port forwarding is disabled to avoid "
923 "man-in-the-middle attacks.");
924 options.num_local_forwards =
925 options.num_remote_forwards = 0;
927 if (options.tun_open != SSH_TUNMODE_NO) {
928 error("Tunnel forwarding is disabled to avoid "
929 "man-in-the-middle attacks.");
930 options.tun_open = SSH_TUNMODE_NO;
933 * XXX Should permit the user to change to use the new id.
934 * This could be done by converting the host key to an
935 * identifying sentence, tell that the host identifies itself
936 * by that sentence, and ask the user if he/she whishes to
937 * accept the authentication.
941 fatal("internal error");
945 if (options.check_host_ip && host_status != HOST_CHANGED &&
946 ip_status == HOST_CHANGED) {
947 snprintf(msg, sizeof(msg),
948 "Warning: the %s host key for '%.200s' "
949 "differs from the key for the IP address '%.128s'"
950 "\nOffending key for IP in %s:%d",
951 type, host, ip, ip_file, ip_line);
952 if (host_status == HOST_OK) {
954 snprintf(msg + len, sizeof(msg) - len,
955 "\nMatching host key in %s:%d",
956 host_file, host_line);
958 if (options.strict_host_key_checking == 1) {
960 error("Exiting, you have requested strict checking.");
962 } else if (options.strict_host_key_checking == 2) {
963 strlcat(msg, "\nAre you sure you want "
964 "to continue connecting (yes/no)? ", sizeof(msg));
982 /* returns 0 if key verifies or -1 if key does NOT verify */
984 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
989 if (options.verify_host_key_dns &&
990 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
992 if (flags & DNS_VERIFY_FOUND) {
994 if (options.verify_host_key_dns == 1 &&
995 flags & DNS_VERIFY_MATCH &&
996 flags & DNS_VERIFY_SECURE)
999 if (flags & DNS_VERIFY_MATCH) {
1000 matching_host_key_dns = 1;
1002 warn_changed_key(host_key);
1003 error("Update the SSHFP RR in DNS with the new "
1004 "host key to get rid of this message.");
1009 /* return ok if the key can be found in an old keyfile */
1010 if (stat(options.system_hostfile2, &st) == 0 ||
1011 stat(options.user_hostfile2, &st) == 0) {
1012 if (check_host_key(host, hostaddr, options.port, host_key,
1013 RDONLY, options.user_hostfile2,
1014 options.system_hostfile2) == 0)
1017 return check_host_key(host, hostaddr, options.port, host_key,
1018 RDRW, options.user_hostfile, options.system_hostfile);
1022 * Starts a dialog with the server, and authenticates the current user on the
1023 * server. This does not need any extra privileges. The basic connection
1024 * to the server must already have been established before this is called.
1025 * If login fails, this function prints an error and never returns.
1026 * This function does not require super-user privileges.
1029 ssh_login(Sensitive *sensitive, const char *orighost,
1030 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1033 char *server_user, *local_user;
1035 local_user = xstrdup(pw->pw_name);
1036 server_user = options.user ? options.user : local_user;
1038 /* Convert the user-supplied hostname into all lowercase. */
1039 host = xstrdup(orighost);
1040 for (cp = host; *cp; cp++)
1042 *cp = (char)tolower(*cp);
1044 /* Exchange protocol version identification strings with the server. */
1045 ssh_exchange_identification(timeout_ms);
1047 /* Put the connection into non-blocking mode. */
1048 packet_set_nonblocking();
1051 /* authenticate user */
1053 ssh_kex2(host, hostaddr);
1054 ssh_userauth2(local_user, server_user, host, sensitive);
1056 ssh_kex(host, hostaddr);
1057 ssh_userauth1(local_user, server_user, host, sensitive);
1063 ssh_put_password(char *password)
1068 if (datafellows & SSH_BUG_PASSWORDPAD) {
1069 packet_put_cstring(password);
1072 size = roundup(strlen(password) + 1, 32);
1073 padded = xcalloc(1, size);
1074 strlcpy(padded, password, size);
1075 packet_put_string(padded, size);
1076 memset(padded, 0, size);
1081 show_key_from_file(const char *file, const char *host, int keytype)
1087 found = key_new(keytype);
1088 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1089 keytype, found, &line))) {
1090 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1091 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1092 logit("WARNING: %s key found for host %s\n"
1094 "%s key fingerprint %s.\n%s\n",
1095 key_type(found), host, file, line,
1096 key_type(found), fp, ra);
1104 /* print all known host keys for a given host, but skip keys of given type */
1106 show_other_keys(const char *host, Key *key)
1108 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1111 for (i = 0; type[i] != -1; i++) {
1112 if (type[i] == key->type)
1114 if (type[i] != KEY_RSA1 &&
1115 show_key_from_file(options.user_hostfile2, host, type[i])) {
1119 if (type[i] != KEY_RSA1 &&
1120 show_key_from_file(options.system_hostfile2, host, type[i])) {
1124 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1128 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1132 debug2("no key of type %d for host %s", type[i], host);
1138 warn_changed_key(Key *host_key)
1141 const char *type = key_type(host_key);
1143 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1145 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1146 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1147 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1148 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1149 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1150 error("It is also possible that the %s host key has just been changed.", type);
1151 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1153 error("Please contact your system administrator.");
1159 * Execute a local command
1162 ssh_local_cmd(const char *args)
1168 if (!options.permit_local_command ||
1169 args == NULL || !*args)
1172 if ((shell = getenv("SHELL")) == NULL)
1173 shell = _PATH_BSHELL;
1177 debug3("Executing %s -c \"%s\"", shell, args);
1178 execl(shell, shell, "-c", args, (char *)NULL);
1179 error("Couldn't execute %s -c \"%s\": %s",
1180 shell, args, strerror(errno));
1182 } else if (pid == -1)
1183 fatal("fork failed: %.100s", strerror(errno));
1184 while (waitpid(pid, &status, 0) == -1)
1186 fatal("Couldn't wait for child: %s", strerror(errno));
1188 if (!WIFEXITED(status))
1191 return (WEXITSTATUS(status));