1 /* $OpenBSD: sshconnect.c,v 1.224 2010/04/16 21:14:27 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>
53 #include "sshconnect.h"
64 char *client_version_string = NULL;
65 char *server_version_string = NULL;
67 static int matching_host_key_dns = 0;
70 extern Options options;
71 extern char *__progname;
72 extern uid_t original_real_uid;
73 extern uid_t original_effective_uid;
74 extern pid_t proxy_command_pid;
76 static int show_other_keys(const char *, Key *);
77 static void warn_changed_key(Key *);
80 * Connect to the given ssh server using a proxy command.
83 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
85 char *command_string, *tmp;
88 char *shell, strport[NI_MAXSERV];
90 if ((shell = getenv("SHELL")) == NULL)
93 /* Convert the port number into a string. */
94 snprintf(strport, sizeof strport, "%hu", port);
97 * Build the final command string in the buffer by making the
98 * appropriate substitutions to the given proxy command.
100 * Use "exec" to avoid "sh -c" processes on some platforms
103 xasprintf(&tmp, "exec %s", proxy_command);
104 command_string = percent_expand(tmp, "h", host, "p", strport,
105 "r", options.user, (char *)NULL);
108 /* Create pipes for communicating with the proxy. */
109 if (pipe(pin) < 0 || pipe(pout) < 0)
110 fatal("Could not create pipes to communicate with the proxy: %.100s",
113 debug("Executing proxy command: %.500s", command_string);
115 /* Fork and execute the proxy command. */
116 if ((pid = fork()) == 0) {
119 /* Child. Permanently give up superuser privileges. */
120 permanently_drop_suid(original_real_uid);
122 /* Redirect stdin and stdout. */
125 if (dup2(pin[0], 0) < 0)
126 perror("dup2 stdin");
130 if (dup2(pout[1], 1) < 0)
131 perror("dup2 stdout");
132 /* Cannot be 1 because pin allocated two descriptors. */
135 /* Stderr is left as it is so that error messages get
136 printed on the user's terminal. */
139 argv[2] = command_string;
142 /* Execute the proxy command. Note that we gave up any
143 extra privileges above. */
144 execv(argv[0], argv);
150 fatal("fork failed: %.100s", strerror(errno));
152 proxy_command_pid = pid; /* save pid to clean up later */
154 /* Close child side of the descriptors. */
158 /* Free the command name. */
159 xfree(command_string);
161 /* Set the connection file descriptors. */
162 packet_set_connection(pout[0], pin[1]);
163 packet_set_timeout(options.server_alive_interval,
164 options.server_alive_count_max);
166 /* Indicate OK return */
171 * Set TCP receive buffer if requested.
172 * Note: tuning needs to happen after the socket is
173 * created but before the connection happens
174 * so winscale is negotiated properly -cjr
177 ssh_set_socket_recvbuf(int sock)
179 void *buf = (void *)&options.tcp_rcv_buf;
180 int sz = sizeof(options.tcp_rcv_buf);
182 int socksizelen = sizeof(int);
184 debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf);
185 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
186 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen);
187 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize);
190 error("Couldn't set socket receive buffer to %d: %.100s",
191 options.tcp_rcv_buf, strerror(errno));
196 * Creates a (possibly privileged) socket for use as the ssh connection.
199 ssh_create_socket(int privileged, struct addrinfo *ai)
202 struct addrinfo hints, *res;
205 * If we are running as root and want to connect to a privileged
206 * port, bind our own socket to a privileged port.
209 int p = IPPORT_RESERVED - 1;
211 sock = rresvport_af(&p, ai->ai_family);
214 error("rresvport: af=%d %.100s", ai->ai_family,
217 debug("Allocated local port %d.", p);
219 if (options.tcp_rcv_buf > 0)
220 ssh_set_socket_recvbuf(sock);
223 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
225 error("socket: %.100s", strerror(errno));
228 fcntl(sock, F_SETFD, FD_CLOEXEC);
230 if (options.tcp_rcv_buf > 0)
231 ssh_set_socket_recvbuf(sock);
233 /* Bind the socket to an alternative local IP address */
234 if (options.bind_address == NULL)
237 memset(&hints, 0, sizeof(hints));
238 hints.ai_family = ai->ai_family;
239 hints.ai_socktype = ai->ai_socktype;
240 hints.ai_protocol = ai->ai_protocol;
241 hints.ai_flags = AI_PASSIVE;
242 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
244 error("getaddrinfo: %s: %s", options.bind_address,
245 ssh_gai_strerror(gaierr));
249 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
250 error("bind: %s: %s", options.bind_address, strerror(errno));
260 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
261 socklen_t addrlen, int *timeoutp)
264 struct timeval tv, t_start;
266 int optval, rc, result = -1;
268 gettimeofday(&t_start, NULL);
270 if (*timeoutp <= 0) {
271 result = connect(sockfd, serv_addr, addrlen);
275 set_nonblock(sockfd);
276 rc = connect(sockfd, serv_addr, addrlen);
278 unset_nonblock(sockfd);
282 if (errno != EINPROGRESS) {
287 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
289 FD_SET(sockfd, fdset);
290 ms_to_timeval(&tv, *timeoutp);
293 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
294 if (rc != -1 || errno != EINTR)
305 debug("select: %s", strerror(errno));
308 /* Completed or failed */
310 optlen = sizeof(optval);
311 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
313 debug("getsockopt: %s", strerror(errno));
321 unset_nonblock(sockfd);
324 /* Should not occur */
325 fatal("Bogus return (%d) from select()", rc);
331 if (result == 0 && *timeoutp > 0) {
332 ms_subtract_diff(&t_start, timeoutp);
333 if (*timeoutp <= 0) {
343 * Opens a TCP/IP connection to the remote server on the given host.
344 * The address of the remote host will be returned in hostaddr.
345 * If port is 0, the default port will be used. If needpriv is true,
346 * a privileged port will be allocated to make the connection.
347 * This requires super-user privileges if needpriv is true.
348 * Connection_attempts specifies the maximum number of tries (one per
349 * second). If proxy_command is non-NULL, it specifies the command (with %h
350 * and %p substituted for host and port, respectively) to use to contact
354 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
355 u_short port, int family, int connection_attempts, int *timeout_ms,
356 int want_keepalive, int needpriv, const char *proxy_command)
360 int sock = -1, attempt;
361 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
362 struct addrinfo hints, *ai, *aitop;
364 debug2("ssh_connect: needpriv %d", needpriv);
366 /* If a proxy command is given, connect using it. */
367 if (proxy_command != NULL)
368 return ssh_proxy_connect(host, port, proxy_command);
370 /* No proxy command. */
372 memset(&hints, 0, sizeof(hints));
373 hints.ai_family = family;
374 hints.ai_socktype = SOCK_STREAM;
375 snprintf(strport, sizeof strport, "%u", port);
376 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
377 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
378 host, ssh_gai_strerror(gaierr));
380 for (attempt = 0; attempt < connection_attempts; attempt++) {
382 /* Sleep a moment before retrying. */
384 debug("Trying again...");
387 * Loop through addresses for this host, and try each one in
388 * sequence until the connection succeeds.
390 for (ai = aitop; ai; ai = ai->ai_next) {
391 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
393 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
394 ntop, sizeof(ntop), strport, sizeof(strport),
395 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
396 error("ssh_connect: getnameinfo failed");
399 debug("Connecting to %.200s [%.100s] port %s.",
400 host, ntop, strport);
402 /* Create a socket for connecting. */
403 sock = ssh_create_socket(needpriv, ai);
405 /* Any error is already output */
408 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
410 /* Successful connection. */
411 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
414 debug("connect to address %s port %s: %s",
415 ntop, strport, strerror(errno));
421 break; /* Successful connection. */
426 /* Return failure if we didn't get a successful connection. */
428 error("ssh: connect to host %s port %s: %s",
429 host, strport, strerror(errno));
433 debug("Connection established.");
435 /* Set SO_KEEPALIVE if requested. */
436 if (want_keepalive &&
437 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
439 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
441 /* Set the connection. */
442 packet_set_connection(sock, sock);
443 packet_set_timeout(options.server_alive_interval,
444 options.server_alive_count_max);
450 * Waits for the server identification string, and sends our own
451 * identification string.
454 ssh_exchange_identification(int timeout_ms)
456 char buf[256], remote_version[256]; /* must be same size! */
457 int remote_major, remote_minor, mismatch;
458 int connection_in = packet_get_connection_in();
459 int connection_out = packet_get_connection_out();
460 int minor1 = PROTOCOL_MINOR_1;
463 int fdsetsz, remaining, rc;
464 struct timeval t_start, t_remaining;
467 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
468 fdset = xcalloc(1, fdsetsz);
470 /* Read other side's version identification. */
471 remaining = timeout_ms;
473 for (i = 0; i < sizeof(buf) - 1; i++) {
474 if (timeout_ms > 0) {
475 gettimeofday(&t_start, NULL);
476 ms_to_timeval(&t_remaining, remaining);
477 FD_SET(connection_in, fdset);
478 rc = select(connection_in + 1, fdset, NULL,
479 fdset, &t_remaining);
480 ms_subtract_diff(&t_start, &remaining);
481 if (rc == 0 || remaining <= 0)
482 fatal("Connection timed out during "
487 fatal("ssh_exchange_identification: "
488 "select: %s", strerror(errno));
492 len = roaming_atomicio(read, connection_in, &buf[i], 1);
494 if (len != 1 && errno == EPIPE)
495 fatal("ssh_exchange_identification: "
496 "Connection closed by remote host");
498 fatal("ssh_exchange_identification: "
499 "read: %.100s", strerror(errno));
500 if (buf[i] == '\r') {
503 continue; /**XXX wait for \n */
505 if (buf[i] == '\n') {
510 fatal("ssh_exchange_identification: "
511 "No banner received");
513 buf[sizeof(buf) - 1] = 0;
514 if (strncmp(buf, "SSH-", 4) == 0)
516 debug("ssh_exchange_identification: %s", buf);
518 server_version_string = xstrdup(buf);
522 * Check that the versions match. In future this might accept
523 * several versions and set appropriate flags to handle them.
525 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
526 &remote_major, &remote_minor, remote_version) != 3)
527 fatal("Bad remote protocol version identification: '%.100s'", buf);
528 debug("Remote protocol version %d.%d, remote software version %.100s",
529 remote_major, remote_minor, remote_version);
531 compat_datafellows(remote_version);
534 switch (remote_major) {
536 if (remote_minor == 99 &&
537 (options.protocol & SSH_PROTO_2) &&
538 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
542 if (!(options.protocol & SSH_PROTO_1)) {
546 if (remote_minor < 3) {
547 fatal("Remote machine has too old SSH software version.");
548 } else if (remote_minor == 3 || remote_minor == 4) {
549 /* We speak 1.3, too. */
552 if (options.forward_agent) {
553 logit("Agent forwarding disabled for protocol 1.3");
554 options.forward_agent = 0;
559 if (options.protocol & SSH_PROTO_2) {
569 fatal("Protocol major versions differ: %d vs. %d",
570 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
572 /* Send our own protocol version identification. */
573 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
574 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
575 compat20 ? PROTOCOL_MINOR_2 : minor1,
576 SSH_RELEASE, compat20 ? "\r\n" : "\n");
577 if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf))
579 fatal("write: %.100s", strerror(errno));
580 client_version_string = xstrdup(buf);
581 chop(client_version_string);
582 chop(server_version_string);
583 debug("Local version string %.100s", client_version_string);
586 /* defaults to 'no' */
588 confirm(const char *prompt)
590 const char *msg, *again = "Please type 'yes' or 'no': ";
594 if (options.batch_mode)
596 for (msg = prompt;;msg = again) {
597 p = read_passphrase(msg, RP_ECHO);
599 (p[0] == '\0') || (p[0] == '\n') ||
600 strncasecmp(p, "no", 2) == 0)
602 if (p && strncasecmp(p, "yes", 3) == 0)
612 check_host_cert(const char *host, const Key *host_key)
616 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
620 if (buffer_len(&host_key->cert->critical) != 0) {
621 error("Certificate for %s contains unsupported "
622 "critical options(s)", host);
629 * check whether the supplied host key is valid, return -1 if the key
630 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
636 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
637 Key *host_key, int readonly, const char *user_hostfile,
638 const char *system_hostfile)
640 Key *file_key, *raw_key = NULL;
642 char *ip = NULL, *host = NULL;
643 char hostline[1000], *hostp, *fp, *ra;
644 HostStatus host_status;
645 HostStatus ip_status;
646 int r, want_cert, local = 0, host_ip_differ = 0;
648 char ntop[NI_MAXHOST];
650 int len, host_line, ip_line, cancelled_forwarding = 0;
651 const char *host_file = NULL, *ip_file = NULL;
654 * Force accepting of the host key for loopback/localhost. The
655 * problem is that if the home directory is NFS-mounted to multiple
656 * machines, localhost will refer to a different machine in each of
657 * them, and the user will get bogus HOST_CHANGED warnings. This
658 * essentially disables host authentication for localhost; however,
659 * this is probably not a real problem.
661 /** hostaddr == 0! */
662 switch (hostaddr->sa_family) {
664 local = (ntohl(((struct sockaddr_in *)hostaddr)->
665 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
666 salen = sizeof(struct sockaddr_in);
669 local = IN6_IS_ADDR_LOOPBACK(
670 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
671 salen = sizeof(struct sockaddr_in6);
675 salen = sizeof(struct sockaddr_storage);
678 if (options.no_host_authentication_for_localhost == 1 && local &&
679 options.host_key_alias == NULL) {
680 debug("Forcing accepting of host key for "
681 "loopback/localhost.");
686 * We don't have the remote ip-address for connections
687 * using a proxy command
689 if (options.proxy_command == NULL) {
690 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
691 NULL, 0, NI_NUMERICHOST) != 0)
692 fatal("check_host_key: getnameinfo failed");
693 ip = put_host_port(ntop, port);
695 ip = xstrdup("<no hostip for proxy command>");
699 * Turn off check_host_ip if the connection is to localhost, via proxy
700 * command or if we don't have a hostname to compare with
702 if (options.check_host_ip && (local ||
703 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
704 options.check_host_ip = 0;
707 * Allow the user to record the key under a different name or
708 * differentiate a non-standard port. This is useful for ssh
709 * tunneling over forwarded connections or if you run multiple
710 * sshd's on different ports on the same machine.
712 if (options.host_key_alias != NULL) {
713 host = xstrdup(options.host_key_alias);
714 debug("using hostkeyalias: %s", host);
716 host = put_host_port(hostname, port);
720 want_cert = key_is_cert(host_key);
721 type = key_type(host_key);
724 * Store the host key from the known host file in here so that we can
725 * compare it with the key for the IP address.
727 file_key = key_new(key_is_cert(host_key) ? KEY_UNSPEC : host_key->type);
730 * Check if the host key is present in the user's list of known
731 * hosts or in the systemwide list.
733 host_file = user_hostfile;
734 host_status = check_host_in_hostfile(host_file, host, host_key,
735 file_key, &host_line);
736 if (host_status == HOST_NEW) {
737 host_file = system_hostfile;
738 host_status = check_host_in_hostfile(host_file, host, host_key,
739 file_key, &host_line);
742 * Also perform check for the ip address, skip the check if we are
743 * localhost, looking for a certificate, or the hostname was an ip
744 * address to begin with.
746 if (!want_cert && options.check_host_ip) {
747 Key *ip_key = key_new(host_key->type);
749 ip_file = user_hostfile;
750 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
752 if (ip_status == HOST_NEW) {
753 ip_file = system_hostfile;
754 ip_status = check_host_in_hostfile(ip_file, ip,
755 host_key, ip_key, &ip_line);
757 if (host_status == HOST_CHANGED &&
758 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
763 ip_status = host_status;
767 switch (host_status) {
769 /* The host is known and the key matches. */
770 debug("Host '%.200s' is known and matches the %s host %s.",
771 host, type, want_cert ? "certificate" : "key");
772 debug("Found %s in %s:%d",
773 want_cert ? "CA key" : "key", host_file, host_line);
774 if (want_cert && !check_host_cert(hostname, host_key))
776 if (options.check_host_ip && ip_status == HOST_NEW) {
777 if (readonly || want_cert)
778 logit("%s host key for IP address "
779 "'%.128s' not in list of known hosts.",
781 else if (!add_host_to_hostfile(user_hostfile, ip,
782 host_key, options.hash_known_hosts))
783 logit("Failed to add the %s host key for IP "
784 "address '%.128s' to the list of known "
785 "hosts (%.30s).", type, ip, user_hostfile);
787 logit("Warning: Permanently added the %s host "
788 "key for IP address '%.128s' to the list "
789 "of known hosts.", type, ip);
790 } else if (options.visual_host_key) {
791 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
792 ra = key_fingerprint(host_key, SSH_FP_MD5,
794 logit("Host key fingerprint is %s\n%s\n", fp, ra);
800 if (options.host_key_alias == NULL && port != 0 &&
801 port != SSH_DEFAULT_PORT) {
802 debug("checking without port identifier");
803 if (check_host_key(hostname, hostaddr, 0, host_key,
804 ROQUIET, user_hostfile, system_hostfile) == 0) {
805 debug("found matching key w/out port");
809 if (readonly || want_cert)
811 /* The host is new. */
812 if (options.strict_host_key_checking == 1) {
814 * User has requested strict host key checking. We
815 * will not add the host key automatically. The only
816 * alternative left is to abort.
818 error("No %s host key is known for %.200s and you "
819 "have requested strict checking.", type, host);
821 } else if (options.strict_host_key_checking == 2) {
822 char msg1[1024], msg2[1024];
824 if (show_other_keys(host, host_key))
825 snprintf(msg1, sizeof(msg1),
826 "\nbut keys of different type are already"
827 " known for this host.");
829 snprintf(msg1, sizeof(msg1), ".");
831 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
832 ra = key_fingerprint(host_key, SSH_FP_MD5,
835 if (options.verify_host_key_dns) {
836 if (matching_host_key_dns)
837 snprintf(msg2, sizeof(msg2),
838 "Matching host key fingerprint"
841 snprintf(msg2, sizeof(msg2),
842 "No matching host key fingerprint"
845 snprintf(msg, sizeof(msg),
846 "The authenticity of host '%.200s (%s)' can't be "
848 "%s key fingerprint is %s.%s%s\n%s"
849 "Are you sure you want to continue connecting "
851 host, ip, msg1, type, fp,
852 options.visual_host_key ? "\n" : "",
853 options.visual_host_key ? ra : "",
861 * If not in strict mode, add the key automatically to the
862 * local known_hosts file.
864 if (options.check_host_ip && ip_status == HOST_NEW) {
865 snprintf(hostline, sizeof(hostline), "%s,%s",
868 if (options.hash_known_hosts) {
869 /* Add hash of host and IP separately */
870 r = add_host_to_hostfile(user_hostfile, host,
871 host_key, options.hash_known_hosts) &&
872 add_host_to_hostfile(user_hostfile, ip,
873 host_key, options.hash_known_hosts);
875 /* Add unhashed "host,ip" */
876 r = add_host_to_hostfile(user_hostfile,
878 options.hash_known_hosts);
881 r = add_host_to_hostfile(user_hostfile, host, host_key,
882 options.hash_known_hosts);
887 logit("Failed to add the host to the list of known "
888 "hosts (%.500s).", user_hostfile);
890 logit("Warning: Permanently added '%.200s' (%s) to the "
891 "list of known hosts.", hostp, type);
894 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
895 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
896 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
897 error("The %s host key for %s is marked as revoked.", type, host);
898 error("This could mean that a stolen key is being used to");
899 error("impersonate this host.");
902 * If strict host key checking is in use, the user will have
903 * to edit the key manually and we can only abort.
905 if (options.strict_host_key_checking) {
906 error("%s host key for %.200s was revoked and you have "
907 "requested strict checking.", type, host);
910 goto continue_unsafe;
915 * This is only a debug() since it is valid to have
916 * CAs with wildcard DNS matches that don't match
917 * all hosts that one might visit.
919 debug("Host certificate authority does not "
920 "match %s in %s:%d", CA_MARKER,
921 host_file, host_line);
924 if (readonly == ROQUIET)
926 if (options.check_host_ip && host_ip_differ) {
928 if (ip_status == HOST_NEW)
929 key_msg = "is unknown";
930 else if (ip_status == HOST_OK)
931 key_msg = "is unchanged";
933 key_msg = "has a different value";
934 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
935 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
936 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
937 error("The %s host key for %s has changed,", type, host);
938 error("and the key for the corresponding IP address %s", ip);
939 error("%s. This could either mean that", key_msg);
940 error("DNS SPOOFING is happening or the IP address for the host");
941 error("and its host key have changed at the same time.");
942 if (ip_status != HOST_NEW)
943 error("Offending key for IP in %s:%d", ip_file, ip_line);
945 /* The host key has changed. */
946 warn_changed_key(host_key);
947 error("Add correct host key in %.100s to get rid of this message.",
949 error("Offending key in %s:%d", host_file, host_line);
952 * If strict host key checking is in use, the user will have
953 * to edit the key manually and we can only abort.
955 if (options.strict_host_key_checking) {
956 error("%s host key for %.200s has changed and you have "
957 "requested strict checking.", type, host);
963 * If strict host key checking has not been requested, allow
964 * the connection but without MITM-able authentication or
967 if (options.password_authentication) {
968 error("Password authentication is disabled to avoid "
969 "man-in-the-middle attacks.");
970 options.password_authentication = 0;
971 cancelled_forwarding = 1;
973 if (options.kbd_interactive_authentication) {
974 error("Keyboard-interactive authentication is disabled"
975 " to avoid man-in-the-middle attacks.");
976 options.kbd_interactive_authentication = 0;
977 options.challenge_response_authentication = 0;
978 cancelled_forwarding = 1;
980 if (options.challenge_response_authentication) {
981 error("Challenge/response authentication is disabled"
982 " to avoid man-in-the-middle attacks.");
983 options.challenge_response_authentication = 0;
984 cancelled_forwarding = 1;
986 if (options.forward_agent) {
987 error("Agent forwarding is disabled to avoid "
988 "man-in-the-middle attacks.");
989 options.forward_agent = 0;
990 cancelled_forwarding = 1;
992 if (options.forward_x11) {
993 error("X11 forwarding is disabled to avoid "
994 "man-in-the-middle attacks.");
995 options.forward_x11 = 0;
996 cancelled_forwarding = 1;
998 if (options.num_local_forwards > 0 ||
999 options.num_remote_forwards > 0) {
1000 error("Port forwarding is disabled to avoid "
1001 "man-in-the-middle attacks.");
1002 options.num_local_forwards =
1003 options.num_remote_forwards = 0;
1004 cancelled_forwarding = 1;
1006 if (options.tun_open != SSH_TUNMODE_NO) {
1007 error("Tunnel forwarding is disabled to avoid "
1008 "man-in-the-middle attacks.");
1009 options.tun_open = SSH_TUNMODE_NO;
1010 cancelled_forwarding = 1;
1012 if (options.exit_on_forward_failure && cancelled_forwarding)
1013 fatal("Error: forwarding disabled due to host key "
1017 * XXX Should permit the user to change to use the new id.
1018 * This could be done by converting the host key to an
1019 * identifying sentence, tell that the host identifies itself
1020 * by that sentence, and ask the user if he/she wishes to
1021 * accept the authentication.
1025 fatal("internal error");
1029 if (options.check_host_ip && host_status != HOST_CHANGED &&
1030 ip_status == HOST_CHANGED) {
1031 snprintf(msg, sizeof(msg),
1032 "Warning: the %s host key for '%.200s' "
1033 "differs from the key for the IP address '%.128s'"
1034 "\nOffending key for IP in %s:%d",
1035 type, host, ip, ip_file, ip_line);
1036 if (host_status == HOST_OK) {
1038 snprintf(msg + len, sizeof(msg) - len,
1039 "\nMatching host key in %s:%d",
1040 host_file, host_line);
1042 if (options.strict_host_key_checking == 1) {
1044 error("Exiting, you have requested strict checking.");
1046 } else if (options.strict_host_key_checking == 2) {
1047 strlcat(msg, "\nAre you sure you want "
1048 "to continue connecting (yes/no)? ", sizeof(msg));
1061 if (want_cert && host_status != HOST_REVOKED) {
1063 * No matching certificate. Downgrade cert to raw key and
1066 debug("No matching CA found. Retry with plain key");
1067 raw_key = key_from_private(host_key);
1068 if (key_drop_cert(raw_key) != 0)
1069 fatal("Couldn't drop certificate");
1073 if (raw_key != NULL)
1080 /* returns 0 if key verifies or -1 if key does NOT verify */
1082 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1087 /* XXX certs are not yet supported for DNS */
1088 if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1089 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1091 if (flags & DNS_VERIFY_FOUND) {
1093 if (options.verify_host_key_dns == 1 &&
1094 flags & DNS_VERIFY_MATCH &&
1095 flags & DNS_VERIFY_SECURE)
1098 if (flags & DNS_VERIFY_MATCH) {
1099 matching_host_key_dns = 1;
1101 warn_changed_key(host_key);
1102 error("Update the SSHFP RR in DNS with the new "
1103 "host key to get rid of this message.");
1108 /* return ok if the key can be found in an old keyfile */
1109 if (stat(options.system_hostfile2, &st) == 0 ||
1110 stat(options.user_hostfile2, &st) == 0) {
1111 if (check_host_key(host, hostaddr, options.port, host_key,
1112 RDONLY, options.user_hostfile2,
1113 options.system_hostfile2) == 0)
1116 return check_host_key(host, hostaddr, options.port, host_key,
1117 RDRW, options.user_hostfile, options.system_hostfile);
1121 * Starts a dialog with the server, and authenticates the current user on the
1122 * server. This does not need any extra privileges. The basic connection
1123 * to the server must already have been established before this is called.
1124 * If login fails, this function prints an error and never returns.
1125 * This function does not require super-user privileges.
1128 ssh_login(Sensitive *sensitive, const char *orighost,
1129 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1132 char *server_user, *local_user;
1134 local_user = xstrdup(pw->pw_name);
1135 server_user = options.user ? options.user : local_user;
1137 /* Convert the user-supplied hostname into all lowercase. */
1138 host = xstrdup(orighost);
1139 for (cp = host; *cp; cp++)
1141 *cp = (char)tolower(*cp);
1143 /* Exchange protocol version identification strings with the server. */
1144 ssh_exchange_identification(timeout_ms);
1146 /* Put the connection into non-blocking mode. */
1147 packet_set_nonblocking();
1150 /* authenticate user */
1152 ssh_kex2(host, hostaddr);
1153 ssh_userauth2(local_user, server_user, host, sensitive);
1155 ssh_kex(host, hostaddr);
1156 ssh_userauth1(local_user, server_user, host, sensitive);
1162 ssh_put_password(char *password)
1167 if (datafellows & SSH_BUG_PASSWORDPAD) {
1168 packet_put_cstring(password);
1171 size = roundup(strlen(password) + 1, 32);
1172 padded = xcalloc(1, size);
1173 strlcpy(padded, password, size);
1174 packet_put_string(padded, size);
1175 memset(padded, 0, size);
1180 show_key_from_file(const char *file, const char *host, int keytype)
1186 found = key_new(keytype);
1187 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1188 keytype, found, &line))) {
1189 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1190 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1191 logit("WARNING: %s key found for host %s\n"
1193 "%s key fingerprint %s.\n%s\n",
1194 key_type(found), host, file, line,
1195 key_type(found), fp, ra);
1203 /* print all known host keys for a given host, but skip keys of given type */
1205 show_other_keys(const char *host, Key *key)
1207 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1210 for (i = 0; type[i] != -1; i++) {
1211 if (type[i] == key->type)
1213 if (type[i] != KEY_RSA1 &&
1214 show_key_from_file(options.user_hostfile2, host, type[i])) {
1218 if (type[i] != KEY_RSA1 &&
1219 show_key_from_file(options.system_hostfile2, host, type[i])) {
1223 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1227 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1231 debug2("no key of type %d for host %s", type[i], host);
1237 warn_changed_key(Key *host_key)
1240 const char *type = key_type(host_key);
1242 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1244 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1245 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1246 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1247 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1248 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1249 error("It is also possible that the %s host key has just been changed.", type);
1250 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1252 error("Please contact your system administrator.");
1258 * Execute a local command
1261 ssh_local_cmd(const char *args)
1267 if (!options.permit_local_command ||
1268 args == NULL || !*args)
1271 if ((shell = getenv("SHELL")) == NULL)
1272 shell = _PATH_BSHELL;
1276 debug3("Executing %s -c \"%s\"", shell, args);
1277 execl(shell, shell, "-c", args, (char *)NULL);
1278 error("Couldn't execute %s -c \"%s\": %s",
1279 shell, args, strerror(errno));
1281 } else if (pid == -1)
1282 fatal("fork failed: %.100s", strerror(errno));
1283 while (waitpid(pid, &status, 0) == -1)
1285 fatal("Couldn't wait for child: %s", strerror(errno));
1287 if (!WIFEXITED(status))
1290 return (WEXITSTATUS(status));