1 /* $OpenBSD: sshconnect.c,v 1.238 2013/05/17 00:13:14 djm 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>
55 #include "sshconnect.h"
66 char *client_version_string = NULL;
67 char *server_version_string = NULL;
69 static int matching_host_key_dns = 0;
71 static pid_t proxy_command_pid = 0;
74 extern Options options;
75 extern char *__progname;
76 extern uid_t original_real_uid;
77 extern uid_t original_effective_uid;
79 static int show_other_keys(struct hostkeys *, Key *);
80 static void warn_changed_key(Key *);
83 * Connect to the given ssh server using a proxy command.
86 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
88 char *command_string, *tmp;
91 char *shell, strport[NI_MAXSERV];
93 if (!strcmp(proxy_command, "-")) {
94 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
95 packet_set_timeout(options.server_alive_interval,
96 options.server_alive_count_max);
100 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
101 shell = _PATH_BSHELL;
103 /* Convert the port number into a string. */
104 snprintf(strport, sizeof strport, "%hu", port);
107 * Build the final command string in the buffer by making the
108 * appropriate substitutions to the given proxy command.
110 * Use "exec" to avoid "sh -c" processes on some platforms
113 xasprintf(&tmp, "exec %s", proxy_command);
114 command_string = percent_expand(tmp, "h", host, "p", strport,
115 "r", options.user, (char *)NULL);
118 /* Create pipes for communicating with the proxy. */
119 if (pipe(pin) < 0 || pipe(pout) < 0)
120 fatal("Could not create pipes to communicate with the proxy: %.100s",
123 debug("Executing proxy command: %.500s", command_string);
125 /* Fork and execute the proxy command. */
126 if ((pid = fork()) == 0) {
129 /* Child. Permanently give up superuser privileges. */
130 permanently_drop_suid(original_real_uid);
132 /* Redirect stdin and stdout. */
135 if (dup2(pin[0], 0) < 0)
136 perror("dup2 stdin");
140 if (dup2(pout[1], 1) < 0)
141 perror("dup2 stdout");
142 /* Cannot be 1 because pin allocated two descriptors. */
145 /* Stderr is left as it is so that error messages get
146 printed on the user's terminal. */
149 argv[2] = command_string;
152 /* Execute the proxy command. Note that we gave up any
153 extra privileges above. */
154 signal(SIGPIPE, SIG_DFL);
155 execv(argv[0], argv);
161 fatal("fork failed: %.100s", strerror(errno));
163 proxy_command_pid = pid; /* save pid to clean up later */
165 /* Close child side of the descriptors. */
169 /* Free the command name. */
170 free(command_string);
172 /* Set the connection file descriptors. */
173 packet_set_connection(pout[0], pin[1]);
174 packet_set_timeout(options.server_alive_interval,
175 options.server_alive_count_max);
177 /* Indicate OK return */
182 ssh_kill_proxy_command(void)
185 * Send SIGHUP to proxy command if used. We don't wait() in
186 * case it hangs and instead rely on init to reap the child
188 if (proxy_command_pid > 1)
189 kill(proxy_command_pid, SIGHUP);
193 * Set TCP receive buffer if requested.
194 * Note: tuning needs to happen after the socket is created but before the
195 * connection happens so winscale is negotiated properly.
198 ssh_set_socket_recvbuf(int sock)
200 void *buf = (void *)&options.tcp_rcv_buf;
201 int socksize, sz = sizeof(options.tcp_rcv_buf);
202 socklen_t len = sizeof(int);
204 debug("setsockopt attempting to set SO_RCVBUF to %d",
205 options.tcp_rcv_buf);
206 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
207 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
208 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno),
211 error("Couldn't set socket receive buffer to %d: %.100s",
212 options.tcp_rcv_buf, strerror(errno));
216 * Creates a (possibly privileged) socket for use as the ssh connection.
219 ssh_create_socket(int privileged, struct addrinfo *ai)
222 struct addrinfo hints, *res;
225 * If we are running as root and want to connect to a privileged
226 * port, bind our own socket to a privileged port.
229 int p = IPPORT_RESERVED - 1;
231 sock = rresvport_af(&p, ai->ai_family);
234 error("rresvport: af=%d %.100s", ai->ai_family,
237 debug("Allocated local port %d.", p);
238 if (options.tcp_rcv_buf > 0)
239 ssh_set_socket_recvbuf(sock);
242 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
244 error("socket: %.100s", strerror(errno));
247 fcntl(sock, F_SETFD, FD_CLOEXEC);
249 if (options.tcp_rcv_buf > 0)
250 ssh_set_socket_recvbuf(sock);
252 /* Bind the socket to an alternative local IP address */
253 if (options.bind_address == NULL)
256 memset(&hints, 0, sizeof(hints));
257 hints.ai_family = ai->ai_family;
258 hints.ai_socktype = ai->ai_socktype;
259 hints.ai_protocol = ai->ai_protocol;
260 hints.ai_flags = AI_PASSIVE;
261 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
263 error("getaddrinfo: %s: %s", options.bind_address,
264 ssh_gai_strerror(gaierr));
268 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
269 error("bind: %s: %s", options.bind_address, strerror(errno));
279 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
280 socklen_t addrlen, int *timeoutp)
283 struct timeval tv, t_start;
285 int optval, rc, result = -1;
287 gettimeofday(&t_start, NULL);
289 if (*timeoutp <= 0) {
290 result = connect(sockfd, serv_addr, addrlen);
294 set_nonblock(sockfd);
295 rc = connect(sockfd, serv_addr, addrlen);
297 unset_nonblock(sockfd);
301 if (errno != EINPROGRESS) {
306 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
308 FD_SET(sockfd, fdset);
309 ms_to_timeval(&tv, *timeoutp);
312 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
313 if (rc != -1 || errno != EINTR)
324 debug("select: %s", strerror(errno));
327 /* Completed or failed */
329 optlen = sizeof(optval);
330 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
332 debug("getsockopt: %s", strerror(errno));
340 unset_nonblock(sockfd);
343 /* Should not occur */
344 fatal("Bogus return (%d) from select()", rc);
350 if (result == 0 && *timeoutp > 0) {
351 ms_subtract_diff(&t_start, timeoutp);
352 if (*timeoutp <= 0) {
362 * Opens a TCP/IP connection to the remote server on the given host.
363 * The address of the remote host will be returned in hostaddr.
364 * If port is 0, the default port will be used. If needpriv is true,
365 * a privileged port will be allocated to make the connection.
366 * This requires super-user privileges if needpriv is true.
367 * Connection_attempts specifies the maximum number of tries (one per
368 * second). If proxy_command is non-NULL, it specifies the command (with %h
369 * and %p substituted for host and port, respectively) to use to contact
373 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
374 u_short port, int family, int connection_attempts, int *timeout_ms,
375 int want_keepalive, int needpriv, const char *proxy_command)
379 int sock = -1, attempt;
380 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
381 struct addrinfo hints, *ai, *aitop;
383 debug2("ssh_connect: needpriv %d", needpriv);
385 /* If a proxy command is given, connect using it. */
386 if (proxy_command != NULL)
387 return ssh_proxy_connect(host, port, proxy_command);
389 /* No proxy command. */
391 memset(&hints, 0, sizeof(hints));
392 hints.ai_family = family;
393 hints.ai_socktype = SOCK_STREAM;
394 snprintf(strport, sizeof strport, "%u", port);
395 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
396 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
397 host, ssh_gai_strerror(gaierr));
399 for (attempt = 0; attempt < connection_attempts; attempt++) {
401 /* Sleep a moment before retrying. */
403 debug("Trying again...");
406 * Loop through addresses for this host, and try each one in
407 * sequence until the connection succeeds.
409 for (ai = aitop; ai; ai = ai->ai_next) {
410 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
412 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
413 ntop, sizeof(ntop), strport, sizeof(strport),
414 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
415 error("ssh_connect: getnameinfo failed");
418 debug("Connecting to %.200s [%.100s] port %s.",
419 host, ntop, strport);
421 /* Create a socket for connecting. */
422 sock = ssh_create_socket(needpriv, ai);
424 /* Any error is already output */
427 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
429 /* Successful connection. */
430 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
433 debug("connect to address %s port %s: %s",
434 ntop, strport, strerror(errno));
440 break; /* Successful connection. */
445 /* Return failure if we didn't get a successful connection. */
447 error("ssh: connect to host %s port %s: %s",
448 host, strport, strerror(errno));
452 debug("Connection established.");
454 /* Set SO_KEEPALIVE if requested. */
455 if (want_keepalive &&
456 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
458 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
460 /* Set the connection. */
461 packet_set_connection(sock, sock);
462 packet_set_timeout(options.server_alive_interval,
463 options.server_alive_count_max);
469 send_client_banner(int connection_out, int minor1)
471 /* Send our own protocol version identification. */
472 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s%s",
473 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
474 compat20 ? PROTOCOL_MINOR_2 : minor1,
475 SSH_VERSION, options.hpn_disabled ? "" : SSH_VERSION_HPN,
476 *options.version_addendum == '\0' ? "" : " ",
477 options.version_addendum, compat20 ? "\r\n" : "\n");
478 if (roaming_atomicio(vwrite, connection_out, client_version_string,
479 strlen(client_version_string)) != strlen(client_version_string))
480 fatal("write: %.100s", strerror(errno));
481 chop(client_version_string);
482 debug("Local version string %.100s", client_version_string);
486 * Waits for the server identification string, and sends our own
487 * identification string.
490 ssh_exchange_identification(int timeout_ms)
492 char buf[256], remote_version[256]; /* must be same size! */
493 int remote_major, remote_minor, mismatch;
494 int connection_in = packet_get_connection_in();
495 int connection_out = packet_get_connection_out();
496 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
499 int fdsetsz, remaining, rc;
500 struct timeval t_start, t_remaining;
503 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
504 fdset = xcalloc(1, fdsetsz);
507 * If we are SSH2-only then we can send the banner immediately and
510 if (options.protocol == SSH_PROTO_2) {
512 send_client_banner(connection_out, 0);
513 client_banner_sent = 1;
516 /* Read other side's version identification. */
517 remaining = timeout_ms;
519 for (i = 0; i < sizeof(buf) - 1; i++) {
520 if (timeout_ms > 0) {
521 gettimeofday(&t_start, NULL);
522 ms_to_timeval(&t_remaining, remaining);
523 FD_SET(connection_in, fdset);
524 rc = select(connection_in + 1, fdset, NULL,
525 fdset, &t_remaining);
526 ms_subtract_diff(&t_start, &remaining);
527 if (rc == 0 || remaining <= 0)
528 fatal("Connection timed out during "
533 fatal("ssh_exchange_identification: "
534 "select: %s", strerror(errno));
538 len = roaming_atomicio(read, connection_in, &buf[i], 1);
540 if (len != 1 && errno == EPIPE)
541 fatal("ssh_exchange_identification: "
542 "Connection closed by remote host");
544 fatal("ssh_exchange_identification: "
545 "read: %.100s", strerror(errno));
546 if (buf[i] == '\r') {
549 continue; /**XXX wait for \n */
551 if (buf[i] == '\n') {
556 fatal("ssh_exchange_identification: "
557 "No banner received");
559 buf[sizeof(buf) - 1] = 0;
560 if (strncmp(buf, "SSH-", 4) == 0)
562 debug("ssh_exchange_identification: %s", buf);
564 server_version_string = xstrdup(buf);
568 * Check that the versions match. In future this might accept
569 * several versions and set appropriate flags to handle them.
571 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
572 &remote_major, &remote_minor, remote_version) != 3)
573 fatal("Bad remote protocol version identification: '%.100s'", buf);
574 debug("Remote protocol version %d.%d, remote software version %.100s",
575 remote_major, remote_minor, remote_version);
577 compat_datafellows(remote_version);
580 switch (remote_major) {
582 if (remote_minor == 99 &&
583 (options.protocol & SSH_PROTO_2) &&
584 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
588 if (!(options.protocol & SSH_PROTO_1)) {
592 if (remote_minor < 3) {
593 fatal("Remote machine has too old SSH software version.");
594 } else if (remote_minor == 3 || remote_minor == 4) {
595 /* We speak 1.3, too. */
598 if (options.forward_agent) {
599 logit("Agent forwarding disabled for protocol 1.3");
600 options.forward_agent = 0;
605 if (options.protocol & SSH_PROTO_2) {
615 fatal("Protocol major versions differ: %d vs. %d",
616 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
618 if (!client_banner_sent)
619 send_client_banner(connection_out, minor1);
620 chop(server_version_string);
623 /* defaults to 'no' */
625 confirm(const char *prompt)
627 const char *msg, *again = "Please type 'yes' or 'no': ";
631 if (options.batch_mode)
633 for (msg = prompt;;msg = again) {
634 p = read_passphrase(msg, RP_ECHO);
636 (p[0] == '\0') || (p[0] == '\n') ||
637 strncasecmp(p, "no", 2) == 0)
639 if (p && strncasecmp(p, "yes", 3) == 0)
648 check_host_cert(const char *host, const Key *host_key)
652 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
656 if (buffer_len(&host_key->cert->critical) != 0) {
657 error("Certificate for %s contains unsupported "
658 "critical options(s)", host);
665 sockaddr_is_local(struct sockaddr *hostaddr)
667 switch (hostaddr->sa_family) {
669 return (ntohl(((struct sockaddr_in *)hostaddr)->
670 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
672 return IN6_IS_ADDR_LOOPBACK(
673 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
680 * Prepare the hostname and ip address strings that are used to lookup
681 * host keys in known_hosts files. These may have a port number appended.
684 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
685 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
687 char ntop[NI_MAXHOST];
690 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
695 addrlen = sizeof(struct sockaddr_in);
698 addrlen = sizeof(struct sockaddr_in6);
701 addrlen = sizeof(struct sockaddr);
706 * We don't have the remote ip-address for connections
707 * using a proxy command
709 if (hostfile_ipaddr != NULL) {
710 if (options.proxy_command == NULL) {
711 if (getnameinfo(hostaddr, addrlen,
712 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
713 fatal("check_host_key: getnameinfo failed");
714 *hostfile_ipaddr = put_host_port(ntop, port);
716 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
722 * Allow the user to record the key under a different name or
723 * differentiate a non-standard port. This is useful for ssh
724 * tunneling over forwarded connections or if you run multiple
725 * sshd's on different ports on the same machine.
727 if (hostfile_hostname != NULL) {
728 if (options.host_key_alias != NULL) {
729 *hostfile_hostname = xstrdup(options.host_key_alias);
730 debug("using hostkeyalias: %s", *hostfile_hostname);
732 *hostfile_hostname = put_host_port(hostname, port);
738 * check whether the supplied host key is valid, return -1 if the key
739 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
745 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
746 Key *host_key, int readonly,
747 char **user_hostfiles, u_int num_user_hostfiles,
748 char **system_hostfiles, u_int num_system_hostfiles)
750 HostStatus host_status;
751 HostStatus ip_status;
753 char *ip = NULL, *host = NULL;
754 char hostline[1000], *hostp, *fp, *ra;
757 const struct hostkey_entry *host_found, *ip_found;
758 int len, cancelled_forwarding = 0;
759 int local = sockaddr_is_local(hostaddr);
760 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
761 struct hostkeys *host_hostkeys, *ip_hostkeys;
765 * Force accepting of the host key for loopback/localhost. The
766 * problem is that if the home directory is NFS-mounted to multiple
767 * machines, localhost will refer to a different machine in each of
768 * them, and the user will get bogus HOST_CHANGED warnings. This
769 * essentially disables host authentication for localhost; however,
770 * this is probably not a real problem.
772 if (options.no_host_authentication_for_localhost == 1 && local &&
773 options.host_key_alias == NULL) {
774 debug("Forcing accepting of host key for "
775 "loopback/localhost.");
780 * Prepare the hostname and address strings used for hostkey lookup.
781 * In some cases, these will have a port number appended.
783 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
786 * Turn off check_host_ip if the connection is to localhost, via proxy
787 * command or if we don't have a hostname to compare with
789 if (options.check_host_ip && (local ||
790 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
791 options.check_host_ip = 0;
793 host_hostkeys = init_hostkeys();
794 for (i = 0; i < num_user_hostfiles; i++)
795 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
796 for (i = 0; i < num_system_hostfiles; i++)
797 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
800 if (!want_cert && options.check_host_ip) {
801 ip_hostkeys = init_hostkeys();
802 for (i = 0; i < num_user_hostfiles; i++)
803 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
804 for (i = 0; i < num_system_hostfiles; i++)
805 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
809 /* Reload these as they may have changed on cert->key downgrade */
810 want_cert = key_is_cert(host_key);
811 type = key_type(host_key);
814 * Check if the host key is present in the user's list of known
815 * hosts or in the systemwide list.
817 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
821 * Also perform check for the ip address, skip the check if we are
822 * localhost, looking for a certificate, or the hostname was an ip
823 * address to begin with.
825 if (!want_cert && ip_hostkeys != NULL) {
826 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
828 if (host_status == HOST_CHANGED &&
829 (ip_status != HOST_CHANGED ||
831 !key_equal(ip_found->key, host_found->key))))
834 ip_status = host_status;
836 switch (host_status) {
838 /* The host is known and the key matches. */
839 debug("Host '%.200s' is known and matches the %s host %s.",
840 host, type, want_cert ? "certificate" : "key");
841 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
842 host_found->file, host_found->line);
843 if (want_cert && !check_host_cert(hostname, host_key))
845 if (options.check_host_ip && ip_status == HOST_NEW) {
846 if (readonly || want_cert)
847 logit("%s host key for IP address "
848 "'%.128s' not in list of known hosts.",
850 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
851 host_key, options.hash_known_hosts))
852 logit("Failed to add the %s host key for IP "
853 "address '%.128s' to the list of known "
854 "hosts (%.30s).", type, ip,
857 logit("Warning: Permanently added the %s host "
858 "key for IP address '%.128s' to the list "
859 "of known hosts.", type, ip);
860 } else if (options.visual_host_key) {
861 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
862 ra = key_fingerprint(host_key, SSH_FP_MD5,
864 logit("Host key fingerprint is %s\n%s\n", fp, ra);
870 if (options.host_key_alias == NULL && port != 0 &&
871 port != SSH_DEFAULT_PORT) {
872 debug("checking without port identifier");
873 if (check_host_key(hostname, hostaddr, 0, host_key,
874 ROQUIET, user_hostfiles, num_user_hostfiles,
875 system_hostfiles, num_system_hostfiles) == 0) {
876 debug("found matching key w/out port");
880 if (readonly || want_cert)
882 /* The host is new. */
883 if (options.strict_host_key_checking == 1) {
885 * User has requested strict host key checking. We
886 * will not add the host key automatically. The only
887 * alternative left is to abort.
889 error("No %s host key is known for %.200s and you "
890 "have requested strict checking.", type, host);
892 } else if (options.strict_host_key_checking == 2) {
893 char msg1[1024], msg2[1024];
895 if (show_other_keys(host_hostkeys, host_key))
896 snprintf(msg1, sizeof(msg1),
897 "\nbut keys of different type are already"
898 " known for this host.");
900 snprintf(msg1, sizeof(msg1), ".");
902 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
903 ra = key_fingerprint(host_key, SSH_FP_MD5,
906 if (options.verify_host_key_dns) {
907 if (matching_host_key_dns)
908 snprintf(msg2, sizeof(msg2),
909 "Matching host key fingerprint"
912 snprintf(msg2, sizeof(msg2),
913 "No matching host key fingerprint"
916 snprintf(msg, sizeof(msg),
917 "The authenticity of host '%.200s (%s)' can't be "
919 "%s key fingerprint is %s.%s%s\n%s"
920 "Are you sure you want to continue connecting "
922 host, ip, msg1, type, fp,
923 options.visual_host_key ? "\n" : "",
924 options.visual_host_key ? ra : "",
932 * If not in strict mode, add the key automatically to the
933 * local known_hosts file.
935 if (options.check_host_ip && ip_status == HOST_NEW) {
936 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
938 if (options.hash_known_hosts) {
939 /* Add hash of host and IP separately */
940 r = add_host_to_hostfile(user_hostfiles[0],
941 host, host_key, options.hash_known_hosts) &&
942 add_host_to_hostfile(user_hostfiles[0], ip,
943 host_key, options.hash_known_hosts);
945 /* Add unhashed "host,ip" */
946 r = add_host_to_hostfile(user_hostfiles[0],
948 options.hash_known_hosts);
951 r = add_host_to_hostfile(user_hostfiles[0], host,
952 host_key, options.hash_known_hosts);
957 logit("Failed to add the host to the list of known "
958 "hosts (%.500s).", user_hostfiles[0]);
960 logit("Warning: Permanently added '%.200s' (%s) to the "
961 "list of known hosts.", hostp, type);
964 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
965 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
966 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
967 error("The %s host key for %s is marked as revoked.", type, host);
968 error("This could mean that a stolen key is being used to");
969 error("impersonate this host.");
972 * If strict host key checking is in use, the user will have
973 * to edit the key manually and we can only abort.
975 if (options.strict_host_key_checking) {
976 error("%s host key for %.200s was revoked and you have "
977 "requested strict checking.", type, host);
980 goto continue_unsafe;
985 * This is only a debug() since it is valid to have
986 * CAs with wildcard DNS matches that don't match
987 * all hosts that one might visit.
989 debug("Host certificate authority does not "
990 "match %s in %s:%lu", CA_MARKER,
991 host_found->file, host_found->line);
994 if (readonly == ROQUIET)
996 if (options.check_host_ip && host_ip_differ) {
998 if (ip_status == HOST_NEW)
999 key_msg = "is unknown";
1000 else if (ip_status == HOST_OK)
1001 key_msg = "is unchanged";
1003 key_msg = "has a different value";
1004 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1005 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1006 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1007 error("The %s host key for %s has changed,", type, host);
1008 error("and the key for the corresponding IP address %s", ip);
1009 error("%s. This could either mean that", key_msg);
1010 error("DNS SPOOFING is happening or the IP address for the host");
1011 error("and its host key have changed at the same time.");
1012 if (ip_status != HOST_NEW)
1013 error("Offending key for IP in %s:%lu",
1014 ip_found->file, ip_found->line);
1016 /* The host key has changed. */
1017 warn_changed_key(host_key);
1018 error("Add correct host key in %.100s to get rid of this message.",
1020 error("Offending %s key in %s:%lu", key_type(host_found->key),
1021 host_found->file, host_found->line);
1024 * If strict host key checking is in use, the user will have
1025 * to edit the key manually and we can only abort.
1027 if (options.strict_host_key_checking) {
1028 error("%s host key for %.200s has changed and you have "
1029 "requested strict checking.", type, host);
1035 * If strict host key checking has not been requested, allow
1036 * the connection but without MITM-able authentication or
1039 if (options.password_authentication) {
1040 error("Password authentication is disabled to avoid "
1041 "man-in-the-middle attacks.");
1042 options.password_authentication = 0;
1043 cancelled_forwarding = 1;
1045 if (options.kbd_interactive_authentication) {
1046 error("Keyboard-interactive authentication is disabled"
1047 " to avoid man-in-the-middle attacks.");
1048 options.kbd_interactive_authentication = 0;
1049 options.challenge_response_authentication = 0;
1050 cancelled_forwarding = 1;
1052 if (options.challenge_response_authentication) {
1053 error("Challenge/response authentication is disabled"
1054 " to avoid man-in-the-middle attacks.");
1055 options.challenge_response_authentication = 0;
1056 cancelled_forwarding = 1;
1058 if (options.forward_agent) {
1059 error("Agent forwarding is disabled to avoid "
1060 "man-in-the-middle attacks.");
1061 options.forward_agent = 0;
1062 cancelled_forwarding = 1;
1064 if (options.forward_x11) {
1065 error("X11 forwarding is disabled to avoid "
1066 "man-in-the-middle attacks.");
1067 options.forward_x11 = 0;
1068 cancelled_forwarding = 1;
1070 if (options.num_local_forwards > 0 ||
1071 options.num_remote_forwards > 0) {
1072 error("Port forwarding is disabled to avoid "
1073 "man-in-the-middle attacks.");
1074 options.num_local_forwards =
1075 options.num_remote_forwards = 0;
1076 cancelled_forwarding = 1;
1078 if (options.tun_open != SSH_TUNMODE_NO) {
1079 error("Tunnel forwarding is disabled to avoid "
1080 "man-in-the-middle attacks.");
1081 options.tun_open = SSH_TUNMODE_NO;
1082 cancelled_forwarding = 1;
1084 if (options.exit_on_forward_failure && cancelled_forwarding)
1085 fatal("Error: forwarding disabled due to host key "
1089 * XXX Should permit the user to change to use the new id.
1090 * This could be done by converting the host key to an
1091 * identifying sentence, tell that the host identifies itself
1092 * by that sentence, and ask the user if he/she wishes to
1093 * accept the authentication.
1097 fatal("internal error");
1101 if (options.check_host_ip && host_status != HOST_CHANGED &&
1102 ip_status == HOST_CHANGED) {
1103 snprintf(msg, sizeof(msg),
1104 "Warning: the %s host key for '%.200s' "
1105 "differs from the key for the IP address '%.128s'"
1106 "\nOffending key for IP in %s:%lu",
1107 type, host, ip, ip_found->file, ip_found->line);
1108 if (host_status == HOST_OK) {
1110 snprintf(msg + len, sizeof(msg) - len,
1111 "\nMatching host key in %s:%lu",
1112 host_found->file, host_found->line);
1114 if (options.strict_host_key_checking == 1) {
1116 error("Exiting, you have requested strict checking.");
1118 } else if (options.strict_host_key_checking == 2) {
1119 strlcat(msg, "\nAre you sure you want "
1120 "to continue connecting (yes/no)? ", sizeof(msg));
1130 if (host_hostkeys != NULL)
1131 free_hostkeys(host_hostkeys);
1132 if (ip_hostkeys != NULL)
1133 free_hostkeys(ip_hostkeys);
1137 if (want_cert && host_status != HOST_REVOKED) {
1139 * No matching certificate. Downgrade cert to raw key and
1142 debug("No matching CA found. Retry with plain key");
1143 raw_key = key_from_private(host_key);
1144 if (key_drop_cert(raw_key) != 0)
1145 fatal("Couldn't drop certificate");
1149 if (raw_key != NULL)
1153 if (host_hostkeys != NULL)
1154 free_hostkeys(host_hostkeys);
1155 if (ip_hostkeys != NULL)
1156 free_hostkeys(ip_hostkeys);
1160 /* returns 0 if key verifies or -1 if key does NOT verify */
1162 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1167 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1168 debug("Server host key: %s %s", key_type(host_key), fp);
1171 /* XXX certs are not yet supported for DNS */
1172 if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1173 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1174 if (flags & DNS_VERIFY_FOUND) {
1176 if (options.verify_host_key_dns == 1 &&
1177 flags & DNS_VERIFY_MATCH &&
1178 flags & DNS_VERIFY_SECURE)
1181 if (flags & DNS_VERIFY_MATCH) {
1182 matching_host_key_dns = 1;
1184 warn_changed_key(host_key);
1185 error("Update the SSHFP RR in DNS with the new "
1186 "host key to get rid of this message.");
1191 return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1192 options.user_hostfiles, options.num_user_hostfiles,
1193 options.system_hostfiles, options.num_system_hostfiles);
1197 * Starts a dialog with the server, and authenticates the current user on the
1198 * server. This does not need any extra privileges. The basic connection
1199 * to the server must already have been established before this is called.
1200 * If login fails, this function prints an error and never returns.
1201 * This function does not require super-user privileges.
1204 ssh_login(Sensitive *sensitive, const char *orighost,
1205 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1208 char *server_user, *local_user;
1210 local_user = xstrdup(pw->pw_name);
1211 server_user = options.user ? options.user : local_user;
1213 /* Convert the user-supplied hostname into all lowercase. */
1214 host = xstrdup(orighost);
1215 for (cp = host; *cp; cp++)
1217 *cp = (char)tolower(*cp);
1219 /* Exchange protocol version identification strings with the server. */
1220 ssh_exchange_identification(timeout_ms);
1222 /* Put the connection into non-blocking mode. */
1223 packet_set_nonblocking();
1226 /* authenticate user */
1228 ssh_kex2(host, hostaddr, port);
1229 ssh_userauth2(local_user, server_user, host, sensitive);
1231 ssh_kex(host, hostaddr);
1232 ssh_userauth1(local_user, server_user, host, sensitive);
1238 ssh_put_password(char *password)
1243 if (datafellows & SSH_BUG_PASSWORDPAD) {
1244 packet_put_cstring(password);
1247 size = roundup(strlen(password) + 1, 32);
1248 padded = xcalloc(1, size);
1249 strlcpy(padded, password, size);
1250 packet_put_string(padded, size);
1251 memset(padded, 0, size);
1255 /* print all known host keys for a given host, but skip keys of given type */
1257 show_other_keys(struct hostkeys *hostkeys, Key *key)
1259 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, KEY_ECDSA, -1};
1262 const struct hostkey_entry *found;
1264 for (i = 0; type[i] != -1; i++) {
1265 if (type[i] == key->type)
1267 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1269 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1270 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1271 logit("WARNING: %s key found for host %s\n"
1273 "%s key fingerprint %s.",
1274 key_type(found->key),
1275 found->host, found->file, found->line,
1276 key_type(found->key), fp);
1277 if (options.visual_host_key)
1287 warn_changed_key(Key *host_key)
1291 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1293 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1294 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1295 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1296 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1297 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1298 error("It is also possible that a host key has just been changed.");
1299 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1300 key_type(host_key), fp);
1301 error("Please contact your system administrator.");
1307 * Execute a local command
1310 ssh_local_cmd(const char *args)
1315 void (*osighand)(int);
1317 if (!options.permit_local_command ||
1318 args == NULL || !*args)
1321 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1322 shell = _PATH_BSHELL;
1324 osighand = signal(SIGCHLD, SIG_DFL);
1327 signal(SIGPIPE, SIG_DFL);
1328 debug3("Executing %s -c \"%s\"", shell, args);
1329 execl(shell, shell, "-c", args, (char *)NULL);
1330 error("Couldn't execute %s -c \"%s\": %s",
1331 shell, args, strerror(errno));
1333 } else if (pid == -1)
1334 fatal("fork failed: %.100s", strerror(errno));
1335 while (waitpid(pid, &status, 0) == -1)
1337 fatal("Couldn't wait for child: %s", strerror(errno));
1338 signal(SIGCHLD, osighand);
1340 if (!WIFEXITED(status))
1343 return (WEXITSTATUS(status));