1 /* $OpenBSD: sshconnect.c,v 1.234 2011/05/24 07:15:47 djm 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>
54 #include "sshconnect.h"
65 char *client_version_string = NULL;
66 char *server_version_string = NULL;
68 static int matching_host_key_dns = 0;
70 static pid_t proxy_command_pid = 0;
73 extern Options options;
74 extern char *__progname;
75 extern uid_t original_real_uid;
76 extern uid_t original_effective_uid;
78 static int show_other_keys(struct hostkeys *, Key *);
79 static void warn_changed_key(Key *);
82 * Connect to the given ssh server using a proxy command.
85 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
87 char *command_string, *tmp;
90 char *shell, strport[NI_MAXSERV];
92 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
95 /* Convert the port number into a string. */
96 snprintf(strport, sizeof strport, "%hu", port);
99 * Build the final command string in the buffer by making the
100 * appropriate substitutions to the given proxy command.
102 * Use "exec" to avoid "sh -c" processes on some platforms
105 xasprintf(&tmp, "exec %s", proxy_command);
106 command_string = percent_expand(tmp, "h", host, "p", strport,
107 "r", options.user, (char *)NULL);
110 /* Create pipes for communicating with the proxy. */
111 if (pipe(pin) < 0 || pipe(pout) < 0)
112 fatal("Could not create pipes to communicate with the proxy: %.100s",
115 debug("Executing proxy command: %.500s", command_string);
117 /* Fork and execute the proxy command. */
118 if ((pid = fork()) == 0) {
121 /* Child. Permanently give up superuser privileges. */
122 permanently_drop_suid(original_real_uid);
124 /* Redirect stdin and stdout. */
127 if (dup2(pin[0], 0) < 0)
128 perror("dup2 stdin");
132 if (dup2(pout[1], 1) < 0)
133 perror("dup2 stdout");
134 /* Cannot be 1 because pin allocated two descriptors. */
137 /* Stderr is left as it is so that error messages get
138 printed on the user's terminal. */
141 argv[2] = command_string;
144 /* Execute the proxy command. Note that we gave up any
145 extra privileges above. */
146 signal(SIGPIPE, SIG_DFL);
147 execv(argv[0], argv);
153 fatal("fork failed: %.100s", strerror(errno));
155 proxy_command_pid = pid; /* save pid to clean up later */
157 /* Close child side of the descriptors. */
161 /* Free the command name. */
162 xfree(command_string);
164 /* Set the connection file descriptors. */
165 packet_set_connection(pout[0], pin[1]);
166 packet_set_timeout(options.server_alive_interval,
167 options.server_alive_count_max);
169 /* Indicate OK return */
174 ssh_kill_proxy_command(void)
177 * Send SIGHUP to proxy command if used. We don't wait() in
178 * case it hangs and instead rely on init to reap the child
180 if (proxy_command_pid > 1)
181 kill(proxy_command_pid, SIGHUP);
185 * Set TCP receive buffer if requested.
186 * Note: tuning needs to happen after the socket is
187 * created but before the connection happens
188 * so winscale is negotiated properly -cjr
191 ssh_set_socket_recvbuf(int sock)
193 void *buf = (void *)&options.tcp_rcv_buf;
194 int sz = sizeof(options.tcp_rcv_buf);
196 int socksizelen = sizeof(int);
198 debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf);
199 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
200 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen);
201 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize);
204 error("Couldn't set socket receive buffer to %d: %.100s",
205 options.tcp_rcv_buf, strerror(errno));
210 * Creates a (possibly privileged) socket for use as the ssh connection.
213 ssh_create_socket(int privileged, struct addrinfo *ai)
216 struct addrinfo hints, *res;
219 * If we are running as root and want to connect to a privileged
220 * port, bind our own socket to a privileged port.
223 int p = IPPORT_RESERVED - 1;
225 sock = rresvport_af(&p, ai->ai_family);
228 error("rresvport: af=%d %.100s", ai->ai_family,
231 debug("Allocated local port %d.", p);
233 if (options.tcp_rcv_buf > 0)
234 ssh_set_socket_recvbuf(sock);
237 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
239 error("socket: %.100s", strerror(errno));
242 fcntl(sock, F_SETFD, FD_CLOEXEC);
244 if (options.tcp_rcv_buf > 0)
245 ssh_set_socket_recvbuf(sock);
247 /* Bind the socket to an alternative local IP address */
248 if (options.bind_address == NULL)
251 memset(&hints, 0, sizeof(hints));
252 hints.ai_family = ai->ai_family;
253 hints.ai_socktype = ai->ai_socktype;
254 hints.ai_protocol = ai->ai_protocol;
255 hints.ai_flags = AI_PASSIVE;
256 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
258 error("getaddrinfo: %s: %s", options.bind_address,
259 ssh_gai_strerror(gaierr));
263 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
264 error("bind: %s: %s", options.bind_address, strerror(errno));
274 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
275 socklen_t addrlen, int *timeoutp)
278 struct timeval tv, t_start;
280 int optval, rc, result = -1;
282 gettimeofday(&t_start, NULL);
284 if (*timeoutp <= 0) {
285 result = connect(sockfd, serv_addr, addrlen);
289 set_nonblock(sockfd);
290 rc = connect(sockfd, serv_addr, addrlen);
292 unset_nonblock(sockfd);
296 if (errno != EINPROGRESS) {
301 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
303 FD_SET(sockfd, fdset);
304 ms_to_timeval(&tv, *timeoutp);
307 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
308 if (rc != -1 || errno != EINTR)
319 debug("select: %s", strerror(errno));
322 /* Completed or failed */
324 optlen = sizeof(optval);
325 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
327 debug("getsockopt: %s", strerror(errno));
335 unset_nonblock(sockfd);
338 /* Should not occur */
339 fatal("Bogus return (%d) from select()", rc);
345 if (result == 0 && *timeoutp > 0) {
346 ms_subtract_diff(&t_start, timeoutp);
347 if (*timeoutp <= 0) {
357 * Opens a TCP/IP connection to the remote server on the given host.
358 * The address of the remote host will be returned in hostaddr.
359 * If port is 0, the default port will be used. If needpriv is true,
360 * a privileged port will be allocated to make the connection.
361 * This requires super-user privileges if needpriv is true.
362 * Connection_attempts specifies the maximum number of tries (one per
363 * second). If proxy_command is non-NULL, it specifies the command (with %h
364 * and %p substituted for host and port, respectively) to use to contact
368 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
369 u_short port, int family, int connection_attempts, int *timeout_ms,
370 int want_keepalive, int needpriv, const char *proxy_command)
374 int sock = -1, attempt;
375 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
376 struct addrinfo hints, *ai, *aitop;
378 debug2("ssh_connect: needpriv %d", needpriv);
380 /* If a proxy command is given, connect using it. */
381 if (proxy_command != NULL)
382 return ssh_proxy_connect(host, port, proxy_command);
384 /* No proxy command. */
386 memset(&hints, 0, sizeof(hints));
387 hints.ai_family = family;
388 hints.ai_socktype = SOCK_STREAM;
389 snprintf(strport, sizeof strport, "%u", port);
390 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
391 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
392 host, ssh_gai_strerror(gaierr));
394 for (attempt = 0; attempt < connection_attempts; attempt++) {
396 /* Sleep a moment before retrying. */
398 debug("Trying again...");
401 * Loop through addresses for this host, and try each one in
402 * sequence until the connection succeeds.
404 for (ai = aitop; ai; ai = ai->ai_next) {
405 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
407 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
408 ntop, sizeof(ntop), strport, sizeof(strport),
409 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
410 error("ssh_connect: getnameinfo failed");
413 debug("Connecting to %.200s [%.100s] port %s.",
414 host, ntop, strport);
416 /* Create a socket for connecting. */
417 sock = ssh_create_socket(needpriv, ai);
419 /* Any error is already output */
422 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
424 /* Successful connection. */
425 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
428 debug("connect to address %s port %s: %s",
429 ntop, strport, strerror(errno));
435 break; /* Successful connection. */
440 /* Return failure if we didn't get a successful connection. */
442 error("ssh: connect to host %s port %s: %s",
443 host, strport, strerror(errno));
447 debug("Connection established.");
449 /* Set SO_KEEPALIVE if requested. */
450 if (want_keepalive &&
451 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
453 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
455 /* Set the connection. */
456 packet_set_connection(sock, sock);
457 packet_set_timeout(options.server_alive_interval,
458 options.server_alive_count_max);
464 * Waits for the server identification string, and sends our own
465 * identification string.
468 ssh_exchange_identification(int timeout_ms)
470 char buf[256], remote_version[256]; /* must be same size! */
471 int remote_major, remote_minor, mismatch;
472 int connection_in = packet_get_connection_in();
473 int connection_out = packet_get_connection_out();
474 int minor1 = PROTOCOL_MINOR_1;
477 int fdsetsz, remaining, rc;
478 struct timeval t_start, t_remaining;
481 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
482 fdset = xcalloc(1, fdsetsz);
484 /* Read other side's version identification. */
485 remaining = timeout_ms;
487 for (i = 0; i < sizeof(buf) - 1; i++) {
488 if (timeout_ms > 0) {
489 gettimeofday(&t_start, NULL);
490 ms_to_timeval(&t_remaining, remaining);
491 FD_SET(connection_in, fdset);
492 rc = select(connection_in + 1, fdset, NULL,
493 fdset, &t_remaining);
494 ms_subtract_diff(&t_start, &remaining);
495 if (rc == 0 || remaining <= 0)
496 fatal("Connection timed out during "
501 fatal("ssh_exchange_identification: "
502 "select: %s", strerror(errno));
506 len = roaming_atomicio(read, connection_in, &buf[i], 1);
508 if (len != 1 && errno == EPIPE)
509 fatal("ssh_exchange_identification: "
510 "Connection closed by remote host");
512 fatal("ssh_exchange_identification: "
513 "read: %.100s", strerror(errno));
514 if (buf[i] == '\r') {
517 continue; /**XXX wait for \n */
519 if (buf[i] == '\n') {
524 fatal("ssh_exchange_identification: "
525 "No banner received");
527 buf[sizeof(buf) - 1] = 0;
528 if (strncmp(buf, "SSH-", 4) == 0)
530 debug("ssh_exchange_identification: %s", buf);
532 server_version_string = xstrdup(buf);
536 * Check that the versions match. In future this might accept
537 * several versions and set appropriate flags to handle them.
539 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
540 &remote_major, &remote_minor, remote_version) != 3)
541 fatal("Bad remote protocol version identification: '%.100s'", buf);
542 debug("Remote protocol version %d.%d, remote software version %.100s",
543 remote_major, remote_minor, remote_version);
545 compat_datafellows(remote_version);
548 switch (remote_major) {
550 if (remote_minor == 99 &&
551 (options.protocol & SSH_PROTO_2) &&
552 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
556 if (!(options.protocol & SSH_PROTO_1)) {
560 if (remote_minor < 3) {
561 fatal("Remote machine has too old SSH software version.");
562 } else if (remote_minor == 3 || remote_minor == 4) {
563 /* We speak 1.3, too. */
566 if (options.forward_agent) {
567 logit("Agent forwarding disabled for protocol 1.3");
568 options.forward_agent = 0;
573 if (options.protocol & SSH_PROTO_2) {
583 fatal("Protocol major versions differ: %d vs. %d",
584 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
586 /* Send our own protocol version identification. */
587 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
588 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
589 compat20 ? PROTOCOL_MINOR_2 : minor1,
590 SSH_RELEASE, compat20 ? "\r\n" : "\n");
591 if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf))
593 fatal("write: %.100s", strerror(errno));
594 client_version_string = xstrdup(buf);
595 chop(client_version_string);
596 chop(server_version_string);
597 debug("Local version string %.100s", client_version_string);
600 /* defaults to 'no' */
602 confirm(const char *prompt)
604 const char *msg, *again = "Please type 'yes' or 'no': ";
608 if (options.batch_mode)
610 for (msg = prompt;;msg = again) {
611 p = read_passphrase(msg, RP_ECHO);
613 (p[0] == '\0') || (p[0] == '\n') ||
614 strncasecmp(p, "no", 2) == 0)
616 if (p && strncasecmp(p, "yes", 3) == 0)
626 check_host_cert(const char *host, const Key *host_key)
630 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
634 if (buffer_len(&host_key->cert->critical) != 0) {
635 error("Certificate for %s contains unsupported "
636 "critical options(s)", host);
643 sockaddr_is_local(struct sockaddr *hostaddr)
645 switch (hostaddr->sa_family) {
647 return (ntohl(((struct sockaddr_in *)hostaddr)->
648 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
650 return IN6_IS_ADDR_LOOPBACK(
651 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
658 * Prepare the hostname and ip address strings that are used to lookup
659 * host keys in known_hosts files. These may have a port number appended.
662 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
663 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
665 char ntop[NI_MAXHOST];
668 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
673 addrlen = sizeof(struct sockaddr_in);
676 addrlen = sizeof(struct sockaddr_in6);
679 addrlen = sizeof(struct sockaddr);
684 * We don't have the remote ip-address for connections
685 * using a proxy command
687 if (hostfile_ipaddr != NULL) {
688 if (options.proxy_command == NULL) {
689 if (getnameinfo(hostaddr, addrlen,
690 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
691 fatal("check_host_key: getnameinfo failed");
692 *hostfile_ipaddr = put_host_port(ntop, port);
694 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
700 * Allow the user to record the key under a different name or
701 * differentiate a non-standard port. This is useful for ssh
702 * tunneling over forwarded connections or if you run multiple
703 * sshd's on different ports on the same machine.
705 if (hostfile_hostname != NULL) {
706 if (options.host_key_alias != NULL) {
707 *hostfile_hostname = xstrdup(options.host_key_alias);
708 debug("using hostkeyalias: %s", *hostfile_hostname);
710 *hostfile_hostname = put_host_port(hostname, port);
716 * check whether the supplied host key is valid, return -1 if the key
717 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
723 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
724 Key *host_key, int readonly,
725 char **user_hostfiles, u_int num_user_hostfiles,
726 char **system_hostfiles, u_int num_system_hostfiles)
728 HostStatus host_status;
729 HostStatus ip_status;
731 char *ip = NULL, *host = NULL;
732 char hostline[1000], *hostp, *fp, *ra;
735 const struct hostkey_entry *host_found, *ip_found;
736 int len, cancelled_forwarding = 0;
737 int local = sockaddr_is_local(hostaddr);
738 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
739 struct hostkeys *host_hostkeys, *ip_hostkeys;
743 * Force accepting of the host key for loopback/localhost. The
744 * problem is that if the home directory is NFS-mounted to multiple
745 * machines, localhost will refer to a different machine in each of
746 * them, and the user will get bogus HOST_CHANGED warnings. This
747 * essentially disables host authentication for localhost; however,
748 * this is probably not a real problem.
750 if (options.no_host_authentication_for_localhost == 1 && local &&
751 options.host_key_alias == NULL) {
752 debug("Forcing accepting of host key for "
753 "loopback/localhost.");
758 * Prepare the hostname and address strings used for hostkey lookup.
759 * In some cases, these will have a port number appended.
761 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
764 * Turn off check_host_ip if the connection is to localhost, via proxy
765 * command or if we don't have a hostname to compare with
767 if (options.check_host_ip && (local ||
768 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
769 options.check_host_ip = 0;
771 host_hostkeys = init_hostkeys();
772 for (i = 0; i < num_user_hostfiles; i++)
773 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
774 for (i = 0; i < num_system_hostfiles; i++)
775 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
778 if (!want_cert && options.check_host_ip) {
779 ip_hostkeys = init_hostkeys();
780 for (i = 0; i < num_user_hostfiles; i++)
781 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
782 for (i = 0; i < num_system_hostfiles; i++)
783 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
787 /* Reload these as they may have changed on cert->key downgrade */
788 want_cert = key_is_cert(host_key);
789 type = key_type(host_key);
792 * Check if the host key is present in the user's list of known
793 * hosts or in the systemwide list.
795 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
799 * Also perform check for the ip address, skip the check if we are
800 * localhost, looking for a certificate, or the hostname was an ip
801 * address to begin with.
803 if (!want_cert && ip_hostkeys != NULL) {
804 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
806 if (host_status == HOST_CHANGED &&
807 (ip_status != HOST_CHANGED ||
809 !key_equal(ip_found->key, host_found->key))))
812 ip_status = host_status;
814 switch (host_status) {
816 /* The host is known and the key matches. */
817 debug("Host '%.200s' is known and matches the %s host %s.",
818 host, type, want_cert ? "certificate" : "key");
819 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
820 host_found->file, host_found->line);
821 if (want_cert && !check_host_cert(hostname, host_key))
823 if (options.check_host_ip && ip_status == HOST_NEW) {
824 if (readonly || want_cert)
825 logit("%s host key for IP address "
826 "'%.128s' not in list of known hosts.",
828 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
829 host_key, options.hash_known_hosts))
830 logit("Failed to add the %s host key for IP "
831 "address '%.128s' to the list of known "
832 "hosts (%.30s).", type, ip,
835 logit("Warning: Permanently added the %s host "
836 "key for IP address '%.128s' to the list "
837 "of known hosts.", type, ip);
838 } else if (options.visual_host_key) {
839 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
840 ra = key_fingerprint(host_key, SSH_FP_MD5,
842 logit("Host key fingerprint is %s\n%s\n", fp, ra);
848 if (options.host_key_alias == NULL && port != 0 &&
849 port != SSH_DEFAULT_PORT) {
850 debug("checking without port identifier");
851 if (check_host_key(hostname, hostaddr, 0, host_key,
852 ROQUIET, user_hostfiles, num_user_hostfiles,
853 system_hostfiles, num_system_hostfiles) == 0) {
854 debug("found matching key w/out port");
858 if (readonly || want_cert)
860 /* The host is new. */
861 if (options.strict_host_key_checking == 1) {
863 * User has requested strict host key checking. We
864 * will not add the host key automatically. The only
865 * alternative left is to abort.
867 error("No %s host key is known for %.200s and you "
868 "have requested strict checking.", type, host);
870 } else if (options.strict_host_key_checking == 2) {
871 char msg1[1024], msg2[1024];
873 if (show_other_keys(host_hostkeys, host_key))
874 snprintf(msg1, sizeof(msg1),
875 "\nbut keys of different type are already"
876 " known for this host.");
878 snprintf(msg1, sizeof(msg1), ".");
880 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
881 ra = key_fingerprint(host_key, SSH_FP_MD5,
884 if (options.verify_host_key_dns) {
885 if (matching_host_key_dns)
886 snprintf(msg2, sizeof(msg2),
887 "Matching host key fingerprint"
890 snprintf(msg2, sizeof(msg2),
891 "No matching host key fingerprint"
894 snprintf(msg, sizeof(msg),
895 "The authenticity of host '%.200s (%s)' can't be "
897 "%s key fingerprint is %s.%s%s\n%s"
898 "Are you sure you want to continue connecting "
900 host, ip, msg1, type, fp,
901 options.visual_host_key ? "\n" : "",
902 options.visual_host_key ? ra : "",
910 * If not in strict mode, add the key automatically to the
911 * local known_hosts file.
913 if (options.check_host_ip && ip_status == HOST_NEW) {
914 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
916 if (options.hash_known_hosts) {
917 /* Add hash of host and IP separately */
918 r = add_host_to_hostfile(user_hostfiles[0],
919 host, host_key, options.hash_known_hosts) &&
920 add_host_to_hostfile(user_hostfiles[0], ip,
921 host_key, options.hash_known_hosts);
923 /* Add unhashed "host,ip" */
924 r = add_host_to_hostfile(user_hostfiles[0],
926 options.hash_known_hosts);
929 r = add_host_to_hostfile(user_hostfiles[0], host,
930 host_key, options.hash_known_hosts);
935 logit("Failed to add the host to the list of known "
936 "hosts (%.500s).", user_hostfiles[0]);
938 logit("Warning: Permanently added '%.200s' (%s) to the "
939 "list of known hosts.", hostp, type);
942 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
943 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
944 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
945 error("The %s host key for %s is marked as revoked.", type, host);
946 error("This could mean that a stolen key is being used to");
947 error("impersonate this host.");
950 * If strict host key checking is in use, the user will have
951 * to edit the key manually and we can only abort.
953 if (options.strict_host_key_checking) {
954 error("%s host key for %.200s was revoked and you have "
955 "requested strict checking.", type, host);
958 goto continue_unsafe;
963 * This is only a debug() since it is valid to have
964 * CAs with wildcard DNS matches that don't match
965 * all hosts that one might visit.
967 debug("Host certificate authority does not "
968 "match %s in %s:%lu", CA_MARKER,
969 host_found->file, host_found->line);
972 if (readonly == ROQUIET)
974 if (options.check_host_ip && host_ip_differ) {
976 if (ip_status == HOST_NEW)
977 key_msg = "is unknown";
978 else if (ip_status == HOST_OK)
979 key_msg = "is unchanged";
981 key_msg = "has a different value";
982 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
983 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
984 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
985 error("The %s host key for %s has changed,", type, host);
986 error("and the key for the corresponding IP address %s", ip);
987 error("%s. This could either mean that", key_msg);
988 error("DNS SPOOFING is happening or the IP address for the host");
989 error("and its host key have changed at the same time.");
990 if (ip_status != HOST_NEW)
991 error("Offending key for IP in %s:%lu",
992 ip_found->file, ip_found->line);
994 /* The host key has changed. */
995 warn_changed_key(host_key);
996 error("Add correct host key in %.100s to get rid of this message.",
998 error("Offending %s key in %s:%lu", key_type(host_found->key),
999 host_found->file, host_found->line);
1002 * If strict host key checking is in use, the user will have
1003 * to edit the key manually and we can only abort.
1005 if (options.strict_host_key_checking) {
1006 error("%s host key for %.200s has changed and you have "
1007 "requested strict checking.", type, host);
1013 * If strict host key checking has not been requested, allow
1014 * the connection but without MITM-able authentication or
1017 if (options.password_authentication) {
1018 error("Password authentication is disabled to avoid "
1019 "man-in-the-middle attacks.");
1020 options.password_authentication = 0;
1021 cancelled_forwarding = 1;
1023 if (options.kbd_interactive_authentication) {
1024 error("Keyboard-interactive authentication is disabled"
1025 " to avoid man-in-the-middle attacks.");
1026 options.kbd_interactive_authentication = 0;
1027 options.challenge_response_authentication = 0;
1028 cancelled_forwarding = 1;
1030 if (options.challenge_response_authentication) {
1031 error("Challenge/response authentication is disabled"
1032 " to avoid man-in-the-middle attacks.");
1033 options.challenge_response_authentication = 0;
1034 cancelled_forwarding = 1;
1036 if (options.forward_agent) {
1037 error("Agent forwarding is disabled to avoid "
1038 "man-in-the-middle attacks.");
1039 options.forward_agent = 0;
1040 cancelled_forwarding = 1;
1042 if (options.forward_x11) {
1043 error("X11 forwarding is disabled to avoid "
1044 "man-in-the-middle attacks.");
1045 options.forward_x11 = 0;
1046 cancelled_forwarding = 1;
1048 if (options.num_local_forwards > 0 ||
1049 options.num_remote_forwards > 0) {
1050 error("Port forwarding is disabled to avoid "
1051 "man-in-the-middle attacks.");
1052 options.num_local_forwards =
1053 options.num_remote_forwards = 0;
1054 cancelled_forwarding = 1;
1056 if (options.tun_open != SSH_TUNMODE_NO) {
1057 error("Tunnel forwarding is disabled to avoid "
1058 "man-in-the-middle attacks.");
1059 options.tun_open = SSH_TUNMODE_NO;
1060 cancelled_forwarding = 1;
1062 if (options.exit_on_forward_failure && cancelled_forwarding)
1063 fatal("Error: forwarding disabled due to host key "
1067 * XXX Should permit the user to change to use the new id.
1068 * This could be done by converting the host key to an
1069 * identifying sentence, tell that the host identifies itself
1070 * by that sentence, and ask the user if he/she wishes to
1071 * accept the authentication.
1075 fatal("internal error");
1079 if (options.check_host_ip && host_status != HOST_CHANGED &&
1080 ip_status == HOST_CHANGED) {
1081 snprintf(msg, sizeof(msg),
1082 "Warning: the %s host key for '%.200s' "
1083 "differs from the key for the IP address '%.128s'"
1084 "\nOffending key for IP in %s:%lu",
1085 type, host, ip, ip_found->file, ip_found->line);
1086 if (host_status == HOST_OK) {
1088 snprintf(msg + len, sizeof(msg) - len,
1089 "\nMatching host key in %s:%lu",
1090 host_found->file, host_found->line);
1092 if (options.strict_host_key_checking == 1) {
1094 error("Exiting, you have requested strict checking.");
1096 } else if (options.strict_host_key_checking == 2) {
1097 strlcat(msg, "\nAre you sure you want "
1098 "to continue connecting (yes/no)? ", sizeof(msg));
1108 if (host_hostkeys != NULL)
1109 free_hostkeys(host_hostkeys);
1110 if (ip_hostkeys != NULL)
1111 free_hostkeys(ip_hostkeys);
1115 if (want_cert && host_status != HOST_REVOKED) {
1117 * No matching certificate. Downgrade cert to raw key and
1120 debug("No matching CA found. Retry with plain key");
1121 raw_key = key_from_private(host_key);
1122 if (key_drop_cert(raw_key) != 0)
1123 fatal("Couldn't drop certificate");
1127 if (raw_key != NULL)
1131 if (host_hostkeys != NULL)
1132 free_hostkeys(host_hostkeys);
1133 if (ip_hostkeys != NULL)
1134 free_hostkeys(ip_hostkeys);
1138 /* returns 0 if key verifies or -1 if key does NOT verify */
1140 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1145 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1146 debug("Server host key: %s %s", key_type(host_key), fp);
1149 /* XXX certs are not yet supported for DNS */
1150 if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1151 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1152 if (flags & DNS_VERIFY_FOUND) {
1154 if (options.verify_host_key_dns == 1 &&
1155 flags & DNS_VERIFY_MATCH &&
1156 flags & DNS_VERIFY_SECURE)
1159 if (flags & DNS_VERIFY_MATCH) {
1160 matching_host_key_dns = 1;
1162 warn_changed_key(host_key);
1163 error("Update the SSHFP RR in DNS with the new "
1164 "host key to get rid of this message.");
1169 return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1170 options.user_hostfiles, options.num_user_hostfiles,
1171 options.system_hostfiles, options.num_system_hostfiles);
1175 * Starts a dialog with the server, and authenticates the current user on the
1176 * server. This does not need any extra privileges. The basic connection
1177 * to the server must already have been established before this is called.
1178 * If login fails, this function prints an error and never returns.
1179 * This function does not require super-user privileges.
1182 ssh_login(Sensitive *sensitive, const char *orighost,
1183 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1186 char *server_user, *local_user;
1188 local_user = xstrdup(pw->pw_name);
1189 server_user = options.user ? options.user : local_user;
1191 /* Convert the user-supplied hostname into all lowercase. */
1192 host = xstrdup(orighost);
1193 for (cp = host; *cp; cp++)
1195 *cp = (char)tolower(*cp);
1197 /* Exchange protocol version identification strings with the server. */
1198 ssh_exchange_identification(timeout_ms);
1200 /* Put the connection into non-blocking mode. */
1201 packet_set_nonblocking();
1204 /* authenticate user */
1206 ssh_kex2(host, hostaddr, port);
1207 ssh_userauth2(local_user, server_user, host, sensitive);
1209 ssh_kex(host, hostaddr);
1210 ssh_userauth1(local_user, server_user, host, sensitive);
1216 ssh_put_password(char *password)
1221 if (datafellows & SSH_BUG_PASSWORDPAD) {
1222 packet_put_cstring(password);
1225 size = roundup(strlen(password) + 1, 32);
1226 padded = xcalloc(1, size);
1227 strlcpy(padded, password, size);
1228 packet_put_string(padded, size);
1229 memset(padded, 0, size);
1233 /* print all known host keys for a given host, but skip keys of given type */
1235 show_other_keys(struct hostkeys *hostkeys, Key *key)
1237 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, KEY_ECDSA, -1};
1240 const struct hostkey_entry *found;
1242 for (i = 0; type[i] != -1; i++) {
1243 if (type[i] == key->type)
1245 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1247 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1248 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1249 logit("WARNING: %s key found for host %s\n"
1251 "%s key fingerprint %s.",
1252 key_type(found->key),
1253 found->host, found->file, found->line,
1254 key_type(found->key), fp);
1255 if (options.visual_host_key)
1265 warn_changed_key(Key *host_key)
1269 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1271 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1272 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1273 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1274 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1275 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1276 error("It is also possible that a host key has just been changed.");
1277 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1278 key_type(host_key), fp);
1279 error("Please contact your system administrator.");
1285 * Execute a local command
1288 ssh_local_cmd(const char *args)
1293 void (*osighand)(int);
1295 if (!options.permit_local_command ||
1296 args == NULL || !*args)
1299 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1300 shell = _PATH_BSHELL;
1302 osighand = signal(SIGCHLD, SIG_DFL);
1305 signal(SIGPIPE, SIG_DFL);
1306 debug3("Executing %s -c \"%s\"", shell, args);
1307 execl(shell, shell, "-c", args, (char *)NULL);
1308 error("Couldn't execute %s -c \"%s\": %s",
1309 shell, args, strerror(errno));
1311 } else if (pid == -1)
1312 fatal("fork failed: %.100s", strerror(errno));
1313 while (waitpid(pid, &status, 0) == -1)
1315 fatal("Couldn't wait for child: %s", strerror(errno));
1316 signal(SIGCHLD, osighand);
1318 if (!WIFEXITED(status))
1321 return (WEXITSTATUS(status));