1 /* $OpenBSD: sshconnect.c,v 1.214 2009/05/28 16:50:16 andreas 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"
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 * Set TCP receive buffer if requested.
170 * Note: tuning needs to happen after the socket is
171 * created but before the connection happens
172 * so winscale is negotiated properly -cjr
175 ssh_set_socket_recvbuf(int sock)
177 void *buf = (void *)&options.tcp_rcv_buf;
178 int sz = sizeof(options.tcp_rcv_buf);
180 int socksizelen = sizeof(int);
182 debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf);
183 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
184 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen);
185 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize);
188 error("Couldn't set socket receive buffer to %d: %.100s",
189 options.tcp_rcv_buf, strerror(errno));
194 * Creates a (possibly privileged) socket for use as the ssh connection.
197 ssh_create_socket(int privileged, struct addrinfo *ai)
200 struct addrinfo hints, *res;
203 * If we are running as root and want to connect to a privileged
204 * port, bind our own socket to a privileged port.
207 int p = IPPORT_RESERVED - 1;
209 sock = rresvport_af(&p, ai->ai_family);
212 error("rresvport: af=%d %.100s", ai->ai_family,
215 debug("Allocated local port %d.", p);
217 if (options.tcp_rcv_buf > 0)
218 ssh_set_socket_recvbuf(sock);
221 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
223 error("socket: %.100s", strerror(errno));
226 if (options.tcp_rcv_buf > 0)
227 ssh_set_socket_recvbuf(sock);
229 if (options.tcp_rcv_buf > 0)
230 ssh_set_socket_recvbuf(sock);
232 /* Bind the socket to an alternative local IP address */
233 if (options.bind_address == NULL)
236 memset(&hints, 0, sizeof(hints));
237 hints.ai_family = ai->ai_family;
238 hints.ai_socktype = ai->ai_socktype;
239 hints.ai_protocol = ai->ai_protocol;
240 hints.ai_flags = AI_PASSIVE;
241 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
243 error("getaddrinfo: %s: %s", options.bind_address,
244 ssh_gai_strerror(gaierr));
248 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
249 error("bind: %s: %s", options.bind_address, strerror(errno));
259 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
260 socklen_t addrlen, int *timeoutp)
263 struct timeval tv, t_start;
265 int optval, rc, result = -1;
267 gettimeofday(&t_start, NULL);
269 if (*timeoutp <= 0) {
270 result = connect(sockfd, serv_addr, addrlen);
274 set_nonblock(sockfd);
275 rc = connect(sockfd, serv_addr, addrlen);
277 unset_nonblock(sockfd);
281 if (errno != EINPROGRESS) {
286 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
288 FD_SET(sockfd, fdset);
289 ms_to_timeval(&tv, *timeoutp);
292 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
293 if (rc != -1 || errno != EINTR)
304 debug("select: %s", strerror(errno));
307 /* Completed or failed */
309 optlen = sizeof(optval);
310 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
312 debug("getsockopt: %s", strerror(errno));
320 unset_nonblock(sockfd);
323 /* Should not occur */
324 fatal("Bogus return (%d) from select()", rc);
330 if (result == 0 && *timeoutp > 0) {
331 ms_subtract_diff(&t_start, timeoutp);
332 if (*timeoutp <= 0) {
342 * Opens a TCP/IP connection to the remote server on the given host.
343 * The address of the remote host will be returned in hostaddr.
344 * If port is 0, the default port will be used. If needpriv is true,
345 * a privileged port will be allocated to make the connection.
346 * This requires super-user privileges if needpriv is true.
347 * Connection_attempts specifies the maximum number of tries (one per
348 * second). If proxy_command is non-NULL, it specifies the command (with %h
349 * and %p substituted for host and port, respectively) to use to contact
353 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
354 u_short port, int family, int connection_attempts, int *timeout_ms,
355 int want_keepalive, int needpriv, const char *proxy_command)
359 int sock = -1, attempt;
360 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
361 struct addrinfo hints, *ai, *aitop;
363 debug2("ssh_connect: needpriv %d", needpriv);
365 /* If a proxy command is given, connect using it. */
366 if (proxy_command != NULL)
367 return ssh_proxy_connect(host, port, proxy_command);
369 /* No proxy command. */
371 memset(&hints, 0, sizeof(hints));
372 hints.ai_family = family;
373 hints.ai_socktype = SOCK_STREAM;
374 snprintf(strport, sizeof strport, "%u", port);
375 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
376 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
377 host, ssh_gai_strerror(gaierr));
379 for (attempt = 0; attempt < connection_attempts; attempt++) {
381 /* Sleep a moment before retrying. */
383 debug("Trying again...");
386 * Loop through addresses for this host, and try each one in
387 * sequence until the connection succeeds.
389 for (ai = aitop; ai; ai = ai->ai_next) {
390 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
392 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
393 ntop, sizeof(ntop), strport, sizeof(strport),
394 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
395 error("ssh_connect: getnameinfo failed");
398 debug("Connecting to %.200s [%.100s] port %s.",
399 host, ntop, strport);
401 /* Create a socket for connecting. */
402 sock = ssh_create_socket(needpriv, ai);
404 /* Any error is already output */
407 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
409 /* Successful connection. */
410 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
413 debug("connect to address %s port %s: %s",
414 ntop, strport, strerror(errno));
420 break; /* Successful connection. */
425 /* Return failure if we didn't get a successful connection. */
427 error("ssh: connect to host %s port %s: %s",
428 host, strport, strerror(errno));
432 debug("Connection established.");
434 /* Set SO_KEEPALIVE if requested. */
435 if (want_keepalive &&
436 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
438 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
440 /* Set the connection. */
441 packet_set_connection(sock, sock);
442 packet_set_timeout(options.server_alive_interval,
443 options.server_alive_count_max);
449 * Waits for the server identification string, and sends our own
450 * identification string.
453 ssh_exchange_identification(int timeout_ms)
455 char buf[256], remote_version[256]; /* must be same size! */
456 int remote_major, remote_minor, mismatch;
457 int connection_in = packet_get_connection_in();
458 int connection_out = packet_get_connection_out();
459 int minor1 = PROTOCOL_MINOR_1;
462 int fdsetsz, remaining, rc;
463 struct timeval t_start, t_remaining;
466 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
467 fdset = xcalloc(1, fdsetsz);
469 /* Read other side's version identification. */
470 remaining = timeout_ms;
472 for (i = 0; i < sizeof(buf) - 1; i++) {
473 if (timeout_ms > 0) {
474 gettimeofday(&t_start, NULL);
475 ms_to_timeval(&t_remaining, remaining);
476 FD_SET(connection_in, fdset);
477 rc = select(connection_in + 1, fdset, NULL,
478 fdset, &t_remaining);
479 ms_subtract_diff(&t_start, &remaining);
480 if (rc == 0 || remaining <= 0)
481 fatal("Connection timed out during "
486 fatal("ssh_exchange_identification: "
487 "select: %s", strerror(errno));
491 len = roaming_atomicio(read, connection_in, &buf[i], 1);
493 if (len != 1 && errno == EPIPE)
494 fatal("ssh_exchange_identification: "
495 "Connection closed by remote host");
497 fatal("ssh_exchange_identification: "
498 "read: %.100s", strerror(errno));
499 if (buf[i] == '\r') {
502 continue; /**XXX wait for \n */
504 if (buf[i] == '\n') {
509 fatal("ssh_exchange_identification: "
510 "No banner received");
512 buf[sizeof(buf) - 1] = 0;
513 if (strncmp(buf, "SSH-", 4) == 0)
515 debug("ssh_exchange_identification: %s", buf);
517 server_version_string = xstrdup(buf);
521 * Check that the versions match. In future this might accept
522 * several versions and set appropriate flags to handle them.
524 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
525 &remote_major, &remote_minor, remote_version) != 3)
526 fatal("Bad remote protocol version identification: '%.100s'", buf);
527 debug("Remote protocol version %d.%d, remote software version %.100s",
528 remote_major, remote_minor, remote_version);
530 compat_datafellows(remote_version);
533 switch (remote_major) {
535 if (remote_minor == 99 &&
536 (options.protocol & SSH_PROTO_2) &&
537 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
541 if (!(options.protocol & SSH_PROTO_1)) {
545 if (remote_minor < 3) {
546 fatal("Remote machine has too old SSH software version.");
547 } else if (remote_minor == 3 || remote_minor == 4) {
548 /* We speak 1.3, too. */
551 if (options.forward_agent) {
552 logit("Agent forwarding disabled for protocol 1.3");
553 options.forward_agent = 0;
558 if (options.protocol & SSH_PROTO_2) {
568 fatal("Protocol major versions differ: %d vs. %d",
569 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
571 /* Send our own protocol version identification. */
572 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
573 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
574 compat20 ? PROTOCOL_MINOR_2 : minor1,
575 SSH_RELEASE, compat20 ? "\r\n" : "\n");
576 if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf))
578 fatal("write: %.100s", strerror(errno));
579 client_version_string = xstrdup(buf);
580 chop(client_version_string);
581 chop(server_version_string);
582 debug("Local version string %.100s", client_version_string);
585 /* defaults to 'no' */
587 confirm(const char *prompt)
589 const char *msg, *again = "Please type 'yes' or 'no': ";
593 if (options.batch_mode)
595 for (msg = prompt;;msg = again) {
596 p = read_passphrase(msg, RP_ECHO);
598 (p[0] == '\0') || (p[0] == '\n') ||
599 strncasecmp(p, "no", 2) == 0)
601 if (p && strncasecmp(p, "yes", 3) == 0)
611 * check whether the supplied host key is valid, return -1 if the key
612 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
618 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
619 Key *host_key, int readonly, const char *user_hostfile,
620 const char *system_hostfile)
623 const char *type = key_type(host_key);
624 char *ip = NULL, *host = NULL;
625 char hostline[1000], *hostp, *fp, *ra;
626 HostStatus host_status;
627 HostStatus ip_status;
628 int r, local = 0, host_ip_differ = 0;
630 char ntop[NI_MAXHOST];
632 int len, host_line, ip_line, cancelled_forwarding = 0;
633 const char *host_file = NULL, *ip_file = NULL;
636 * Force accepting of the host key for loopback/localhost. The
637 * problem is that if the home directory is NFS-mounted to multiple
638 * machines, localhost will refer to a different machine in each of
639 * them, and the user will get bogus HOST_CHANGED warnings. This
640 * essentially disables host authentication for localhost; however,
641 * this is probably not a real problem.
643 /** hostaddr == 0! */
644 switch (hostaddr->sa_family) {
646 local = (ntohl(((struct sockaddr_in *)hostaddr)->
647 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
648 salen = sizeof(struct sockaddr_in);
651 local = IN6_IS_ADDR_LOOPBACK(
652 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
653 salen = sizeof(struct sockaddr_in6);
657 salen = sizeof(struct sockaddr_storage);
660 if (options.no_host_authentication_for_localhost == 1 && local &&
661 options.host_key_alias == NULL) {
662 debug("Forcing accepting of host key for "
663 "loopback/localhost.");
668 * We don't have the remote ip-address for connections
669 * using a proxy command
671 if (options.proxy_command == NULL) {
672 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
673 NULL, 0, NI_NUMERICHOST) != 0)
674 fatal("check_host_key: getnameinfo failed");
675 ip = put_host_port(ntop, port);
677 ip = xstrdup("<no hostip for proxy command>");
681 * Turn off check_host_ip if the connection is to localhost, via proxy
682 * command or if we don't have a hostname to compare with
684 if (options.check_host_ip && (local ||
685 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
686 options.check_host_ip = 0;
689 * Allow the user to record the key under a different name or
690 * differentiate a non-standard port. This is useful for ssh
691 * tunneling over forwarded connections or if you run multiple
692 * sshd's on different ports on the same machine.
694 if (options.host_key_alias != NULL) {
695 host = xstrdup(options.host_key_alias);
696 debug("using hostkeyalias: %s", host);
698 host = put_host_port(hostname, port);
702 * Store the host key from the known host file in here so that we can
703 * compare it with the key for the IP address.
705 file_key = key_new(host_key->type);
708 * Check if the host key is present in the user's list of known
709 * hosts or in the systemwide list.
711 host_file = user_hostfile;
712 host_status = check_host_in_hostfile(host_file, host, host_key,
713 file_key, &host_line);
714 if (host_status == HOST_NEW) {
715 host_file = system_hostfile;
716 host_status = check_host_in_hostfile(host_file, host, host_key,
717 file_key, &host_line);
720 * Also perform check for the ip address, skip the check if we are
721 * localhost or the hostname was an ip address to begin with
723 if (options.check_host_ip) {
724 Key *ip_key = key_new(host_key->type);
726 ip_file = user_hostfile;
727 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
729 if (ip_status == HOST_NEW) {
730 ip_file = system_hostfile;
731 ip_status = check_host_in_hostfile(ip_file, ip,
732 host_key, ip_key, &ip_line);
734 if (host_status == HOST_CHANGED &&
735 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
740 ip_status = host_status;
744 switch (host_status) {
746 /* The host is known and the key matches. */
747 debug("Host '%.200s' is known and matches the %s host key.",
749 debug("Found key in %s:%d", host_file, host_line);
750 if (options.check_host_ip && ip_status == HOST_NEW) {
752 logit("%s host key for IP address "
753 "'%.128s' not in list of known hosts.",
755 else if (!add_host_to_hostfile(user_hostfile, ip,
756 host_key, options.hash_known_hosts))
757 logit("Failed to add the %s host key for IP "
758 "address '%.128s' to the list of known "
759 "hosts (%.30s).", type, ip, user_hostfile);
761 logit("Warning: Permanently added the %s host "
762 "key for IP address '%.128s' to the list "
763 "of known hosts.", type, ip);
764 } else if (options.visual_host_key) {
765 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
766 ra = key_fingerprint(host_key, SSH_FP_MD5,
768 logit("Host key fingerprint is %s\n%s\n", fp, ra);
774 if (options.host_key_alias == NULL && port != 0 &&
775 port != SSH_DEFAULT_PORT) {
776 debug("checking without port identifier");
777 if (check_host_key(hostname, hostaddr, 0, host_key,
778 ROQUIET, user_hostfile, system_hostfile) == 0) {
779 debug("found matching key w/out port");
785 /* The host is new. */
786 if (options.strict_host_key_checking == 1) {
788 * User has requested strict host key checking. We
789 * will not add the host key automatically. The only
790 * alternative left is to abort.
792 error("No %s host key is known for %.200s and you "
793 "have requested strict checking.", type, host);
795 } else if (options.strict_host_key_checking == 2) {
796 char msg1[1024], msg2[1024];
798 if (show_other_keys(host, host_key))
799 snprintf(msg1, sizeof(msg1),
800 "\nbut keys of different type are already"
801 " known for this host.");
803 snprintf(msg1, sizeof(msg1), ".");
805 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
806 ra = key_fingerprint(host_key, SSH_FP_MD5,
809 if (options.verify_host_key_dns) {
810 if (matching_host_key_dns)
811 snprintf(msg2, sizeof(msg2),
812 "Matching host key fingerprint"
815 snprintf(msg2, sizeof(msg2),
816 "No matching host key fingerprint"
819 snprintf(msg, sizeof(msg),
820 "The authenticity of host '%.200s (%s)' can't be "
822 "%s key fingerprint is %s.%s%s\n%s"
823 "Are you sure you want to continue connecting "
825 host, ip, msg1, type, fp,
826 options.visual_host_key ? "\n" : "",
827 options.visual_host_key ? ra : "",
835 * If not in strict mode, add the key automatically to the
836 * local known_hosts file.
838 if (options.check_host_ip && ip_status == HOST_NEW) {
839 snprintf(hostline, sizeof(hostline), "%s,%s",
842 if (options.hash_known_hosts) {
843 /* Add hash of host and IP separately */
844 r = add_host_to_hostfile(user_hostfile, host,
845 host_key, options.hash_known_hosts) &&
846 add_host_to_hostfile(user_hostfile, ip,
847 host_key, options.hash_known_hosts);
849 /* Add unhashed "host,ip" */
850 r = add_host_to_hostfile(user_hostfile,
852 options.hash_known_hosts);
855 r = add_host_to_hostfile(user_hostfile, host, host_key,
856 options.hash_known_hosts);
861 logit("Failed to add the host to the list of known "
862 "hosts (%.500s).", user_hostfile);
864 logit("Warning: Permanently added '%.200s' (%s) to the "
865 "list of known hosts.", hostp, type);
868 if (readonly == ROQUIET)
870 if (options.check_host_ip && host_ip_differ) {
872 if (ip_status == HOST_NEW)
873 key_msg = "is unknown";
874 else if (ip_status == HOST_OK)
875 key_msg = "is unchanged";
877 key_msg = "has a different value";
878 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
879 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
880 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
881 error("The %s host key for %s has changed,", type, host);
882 error("and the key for the corresponding IP address %s", ip);
883 error("%s. This could either mean that", key_msg);
884 error("DNS SPOOFING is happening or the IP address for the host");
885 error("and its host key have changed at the same time.");
886 if (ip_status != HOST_NEW)
887 error("Offending key for IP in %s:%d", ip_file, ip_line);
889 /* The host key has changed. */
890 warn_changed_key(host_key);
891 error("Add correct host key in %.100s to get rid of this message.",
893 error("Offending key in %s:%d", host_file, host_line);
896 * If strict host key checking is in use, the user will have
897 * to edit the key manually and we can only abort.
899 if (options.strict_host_key_checking) {
900 error("%s host key for %.200s has changed and you have "
901 "requested strict checking.", type, host);
906 * If strict host key checking has not been requested, allow
907 * the connection but without MITM-able authentication or
910 if (options.password_authentication) {
911 error("Password authentication is disabled to avoid "
912 "man-in-the-middle attacks.");
913 options.password_authentication = 0;
914 cancelled_forwarding = 1;
916 if (options.kbd_interactive_authentication) {
917 error("Keyboard-interactive authentication is disabled"
918 " to avoid man-in-the-middle attacks.");
919 options.kbd_interactive_authentication = 0;
920 options.challenge_response_authentication = 0;
921 cancelled_forwarding = 1;
923 if (options.challenge_response_authentication) {
924 error("Challenge/response authentication is disabled"
925 " to avoid man-in-the-middle attacks.");
926 options.challenge_response_authentication = 0;
927 cancelled_forwarding = 1;
929 if (options.forward_agent) {
930 error("Agent forwarding is disabled to avoid "
931 "man-in-the-middle attacks.");
932 options.forward_agent = 0;
933 cancelled_forwarding = 1;
935 if (options.forward_x11) {
936 error("X11 forwarding is disabled to avoid "
937 "man-in-the-middle attacks.");
938 options.forward_x11 = 0;
939 cancelled_forwarding = 1;
941 if (options.num_local_forwards > 0 ||
942 options.num_remote_forwards > 0) {
943 error("Port forwarding is disabled to avoid "
944 "man-in-the-middle attacks.");
945 options.num_local_forwards =
946 options.num_remote_forwards = 0;
947 cancelled_forwarding = 1;
949 if (options.tun_open != SSH_TUNMODE_NO) {
950 error("Tunnel forwarding is disabled to avoid "
951 "man-in-the-middle attacks.");
952 options.tun_open = SSH_TUNMODE_NO;
953 cancelled_forwarding = 1;
955 if (options.exit_on_forward_failure && cancelled_forwarding)
956 fatal("Error: forwarding disabled due to host key "
960 * XXX Should permit the user to change to use the new id.
961 * This could be done by converting the host key to an
962 * identifying sentence, tell that the host identifies itself
963 * by that sentence, and ask the user if he/she whishes to
964 * accept the authentication.
968 fatal("internal error");
972 if (options.check_host_ip && host_status != HOST_CHANGED &&
973 ip_status == HOST_CHANGED) {
974 snprintf(msg, sizeof(msg),
975 "Warning: the %s host key for '%.200s' "
976 "differs from the key for the IP address '%.128s'"
977 "\nOffending key for IP in %s:%d",
978 type, host, ip, ip_file, ip_line);
979 if (host_status == HOST_OK) {
981 snprintf(msg + len, sizeof(msg) - len,
982 "\nMatching host key in %s:%d",
983 host_file, host_line);
985 if (options.strict_host_key_checking == 1) {
987 error("Exiting, you have requested strict checking.");
989 } else if (options.strict_host_key_checking == 2) {
990 strlcat(msg, "\nAre you sure you want "
991 "to continue connecting (yes/no)? ", sizeof(msg));
1009 /* returns 0 if key verifies or -1 if key does NOT verify */
1011 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1016 if (options.verify_host_key_dns &&
1017 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1019 if (flags & DNS_VERIFY_FOUND) {
1021 if (options.verify_host_key_dns == 1 &&
1022 flags & DNS_VERIFY_MATCH &&
1023 flags & DNS_VERIFY_SECURE)
1026 if (flags & DNS_VERIFY_MATCH) {
1027 matching_host_key_dns = 1;
1029 warn_changed_key(host_key);
1030 error("Update the SSHFP RR in DNS with the new "
1031 "host key to get rid of this message.");
1036 /* return ok if the key can be found in an old keyfile */
1037 if (stat(options.system_hostfile2, &st) == 0 ||
1038 stat(options.user_hostfile2, &st) == 0) {
1039 if (check_host_key(host, hostaddr, options.port, host_key,
1040 RDONLY, options.user_hostfile2,
1041 options.system_hostfile2) == 0)
1044 return check_host_key(host, hostaddr, options.port, host_key,
1045 RDRW, options.user_hostfile, options.system_hostfile);
1049 * Starts a dialog with the server, and authenticates the current user on the
1050 * server. This does not need any extra privileges. The basic connection
1051 * to the server must already have been established before this is called.
1052 * If login fails, this function prints an error and never returns.
1053 * This function does not require super-user privileges.
1056 ssh_login(Sensitive *sensitive, const char *orighost,
1057 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1060 char *server_user, *local_user;
1062 local_user = xstrdup(pw->pw_name);
1063 server_user = options.user ? options.user : local_user;
1065 /* Convert the user-supplied hostname into all lowercase. */
1066 host = xstrdup(orighost);
1067 for (cp = host; *cp; cp++)
1069 *cp = (char)tolower(*cp);
1071 /* Exchange protocol version identification strings with the server. */
1072 ssh_exchange_identification(timeout_ms);
1074 /* Put the connection into non-blocking mode. */
1075 packet_set_nonblocking();
1078 /* authenticate user */
1080 ssh_kex2(host, hostaddr);
1081 ssh_userauth2(local_user, server_user, host, sensitive);
1083 ssh_kex(host, hostaddr);
1084 ssh_userauth1(local_user, server_user, host, sensitive);
1090 ssh_put_password(char *password)
1095 if (datafellows & SSH_BUG_PASSWORDPAD) {
1096 packet_put_cstring(password);
1099 size = roundup(strlen(password) + 1, 32);
1100 padded = xcalloc(1, size);
1101 strlcpy(padded, password, size);
1102 packet_put_string(padded, size);
1103 memset(padded, 0, size);
1108 show_key_from_file(const char *file, const char *host, int keytype)
1114 found = key_new(keytype);
1115 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1116 keytype, found, &line))) {
1117 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1118 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1119 logit("WARNING: %s key found for host %s\n"
1121 "%s key fingerprint %s.\n%s\n",
1122 key_type(found), host, file, line,
1123 key_type(found), fp, ra);
1131 /* print all known host keys for a given host, but skip keys of given type */
1133 show_other_keys(const char *host, Key *key)
1135 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1138 for (i = 0; type[i] != -1; i++) {
1139 if (type[i] == key->type)
1141 if (type[i] != KEY_RSA1 &&
1142 show_key_from_file(options.user_hostfile2, host, type[i])) {
1146 if (type[i] != KEY_RSA1 &&
1147 show_key_from_file(options.system_hostfile2, host, type[i])) {
1151 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1155 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1159 debug2("no key of type %d for host %s", type[i], host);
1165 warn_changed_key(Key *host_key)
1168 const char *type = key_type(host_key);
1170 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1172 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1173 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1174 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1175 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1176 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1177 error("It is also possible that the %s host key has just been changed.", type);
1178 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1180 error("Please contact your system administrator.");
1186 * Execute a local command
1189 ssh_local_cmd(const char *args)
1195 if (!options.permit_local_command ||
1196 args == NULL || !*args)
1199 if ((shell = getenv("SHELL")) == NULL)
1200 shell = _PATH_BSHELL;
1204 debug3("Executing %s -c \"%s\"", shell, args);
1205 execl(shell, shell, "-c", args, (char *)NULL);
1206 error("Couldn't execute %s -c \"%s\": %s",
1207 shell, args, strerror(errno));
1209 } else if (pid == -1)
1210 fatal("fork failed: %.100s", strerror(errno));
1211 while (waitpid(pid, &status, 0) == -1)
1213 fatal("Couldn't wait for child: %s", strerror(errno));
1215 if (!WIFEXITED(status))
1218 return (WEXITSTATUS(status));