1 /* $OpenBSD: sshconnect.c,v 1.203 2007/12/27 14:22:08 dtucker Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
18 #include <sys/types.h>
21 #include <sys/socket.h>
22 #ifdef HAVE_SYS_TIME_H
23 # include <sys/time.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
52 #include "sshconnect.h"
61 char *client_version_string
= NULL
;
62 char *server_version_string
= NULL
;
64 static int matching_host_key_dns
= 0;
67 extern Options options
;
68 extern char *__progname
;
69 extern uid_t original_real_uid
;
70 extern uid_t original_effective_uid
;
71 extern pid_t proxy_command_pid
;
73 #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
74 #define INET6_ADDRSTRLEN 46
77 static int show_other_keys(const char *, Key
*);
78 static void warn_changed_key(Key
*);
81 ms_subtract_diff(struct timeval
*start
, int *ms
)
83 struct timeval diff
, finish
;
85 gettimeofday(&finish
, NULL
);
86 timersub(&finish
, start
, &diff
);
87 *ms
-= (diff
.tv_sec
* 1000) + (diff
.tv_usec
/ 1000);
91 ms_to_timeval(struct timeval
*tv
, int ms
)
93 tv
->tv_sec
= ms
/ 1000;
94 tv
->tv_usec
= (ms
% 1000) * 1000;
98 * Connect to the given ssh server using a proxy command.
101 ssh_proxy_connect(const char *host
, u_short port
, const char *proxy_command
)
103 char *command_string
, *tmp
;
106 char *shell
, strport
[NI_MAXSERV
];
108 if ((shell
= getenv("SHELL")) == NULL
)
109 shell
= _PATH_BSHELL
;
111 /* Convert the port number into a string. */
112 snprintf(strport
, sizeof strport
, "%hu", port
);
115 * Build the final command string in the buffer by making the
116 * appropriate substitutions to the given proxy command.
118 * Use "exec" to avoid "sh -c" processes on some platforms
121 xasprintf(&tmp
, "exec %s", proxy_command
);
122 command_string
= percent_expand(tmp
, "h", host
,
123 "p", strport
, (char *)NULL
);
126 /* Create pipes for communicating with the proxy. */
127 if (pipe(pin
) < 0 || pipe(pout
) < 0)
128 fatal("Could not create pipes to communicate with the proxy: %.100s",
131 debug("Executing proxy command: %.500s", command_string
);
133 /* Fork and execute the proxy command. */
134 if ((pid
= fork()) == 0) {
137 /* Child. Permanently give up superuser privileges. */
138 permanently_drop_suid(original_real_uid
);
140 /* Redirect stdin and stdout. */
143 if (dup2(pin
[0], 0) < 0)
144 perror("dup2 stdin");
148 if (dup2(pout
[1], 1) < 0)
149 perror("dup2 stdout");
150 /* Cannot be 1 because pin allocated two descriptors. */
153 /* Stderr is left as it is so that error messages get
154 printed on the user's terminal. */
157 argv
[2] = command_string
;
160 /* Execute the proxy command. Note that we gave up any
161 extra privileges above. */
162 execv(argv
[0], argv
);
168 fatal("fork failed: %.100s", strerror(errno
));
170 proxy_command_pid
= pid
; /* save pid to clean up later */
172 /* Close child side of the descriptors. */
176 /* Free the command name. */
177 xfree(command_string
);
179 /* Set the connection file descriptors. */
180 packet_set_connection(pout
[0], pin
[1]);
182 /* Indicate OK return */
187 * Creates a (possibly privileged) socket for use as the ssh connection.
190 ssh_create_socket(int privileged
, struct addrinfo
*ai
)
193 struct addrinfo hints
, *res
;
196 * If we are running as root and want to connect to a privileged
197 * port, bind our own socket to a privileged port.
200 int p
= IPPORT_RESERVED
- 1;
202 sock
= rresvport_af(&p
, ai
->ai_family
);
205 error("rresvport: af=%d %.100s", ai
->ai_family
,
208 debug("Allocated local port %d.", p
);
211 sock
= socket(ai
->ai_family
, ai
->ai_socktype
, ai
->ai_protocol
);
213 error("socket: %.100s", strerror(errno
));
215 /* Bind the socket to an alternative local IP address */
216 if (options
.bind_address
== NULL
)
219 memset(&hints
, 0, sizeof(hints
));
220 hints
.ai_family
= ai
->ai_family
;
221 hints
.ai_socktype
= ai
->ai_socktype
;
222 hints
.ai_protocol
= ai
->ai_protocol
;
223 hints
.ai_flags
= AI_PASSIVE
;
224 gaierr
= getaddrinfo(options
.bind_address
, "0", &hints
, &res
);
226 error("getaddrinfo: %s: %s", options
.bind_address
,
227 ssh_gai_strerror(gaierr
));
231 if (bind(sock
, res
->ai_addr
, res
->ai_addrlen
) < 0) {
232 error("bind: %s: %s", options
.bind_address
, strerror(errno
));
242 timeout_connect(int sockfd
, const struct sockaddr
*serv_addr
,
243 socklen_t addrlen
, int *timeoutp
)
246 struct timeval tv
, t_start
;
248 int optval
, rc
, result
= -1;
250 gettimeofday(&t_start
, NULL
);
252 if (*timeoutp
<= 0) {
253 result
= connect(sockfd
, serv_addr
, addrlen
);
257 set_nonblock(sockfd
);
258 rc
= connect(sockfd
, serv_addr
, addrlen
);
260 unset_nonblock(sockfd
);
264 if (errno
!= EINPROGRESS
) {
269 fdset
= (fd_set
*)xcalloc(howmany(sockfd
+ 1, NFDBITS
),
271 FD_SET(sockfd
, fdset
);
272 ms_to_timeval(&tv
, *timeoutp
);
275 rc
= select(sockfd
+ 1, NULL
, fdset
, NULL
, &tv
);
276 if (rc
!= -1 || errno
!= EINTR
)
287 debug("select: %s", strerror(errno
));
290 /* Completed or failed */
292 optlen
= sizeof(optval
);
293 if (getsockopt(sockfd
, SOL_SOCKET
, SO_ERROR
, &optval
,
295 debug("getsockopt: %s", strerror(errno
));
303 unset_nonblock(sockfd
);
306 /* Should not occur */
307 fatal("Bogus return (%d) from select()", rc
);
313 if (result
== 0 && *timeoutp
> 0) {
314 ms_subtract_diff(&t_start
, timeoutp
);
315 if (*timeoutp
<= 0) {
325 * Opens a TCP/IP connection to the remote server on the given host.
326 * The address of the remote host will be returned in hostaddr.
327 * If port is 0, the default port will be used. If needpriv is true,
328 * a privileged port will be allocated to make the connection.
329 * This requires super-user privileges if needpriv is true.
330 * Connection_attempts specifies the maximum number of tries (one per
331 * second). If proxy_command is non-NULL, it specifies the command (with %h
332 * and %p substituted for host and port, respectively) to use to contact
336 ssh_connect(const char *host
, struct sockaddr_storage
* hostaddr
,
337 u_short port
, int family
, int connection_attempts
, int *timeout_ms
,
338 int want_keepalive
, int needpriv
, const char *proxy_command
)
342 int sock
= -1, attempt
;
343 char ntop
[NI_MAXHOST
], strport
[NI_MAXSERV
];
344 struct addrinfo hints
, *ai
, *aitop
;
346 debug2("ssh_connect: needpriv %d", needpriv
);
348 /* If a proxy command is given, connect using it. */
349 if (proxy_command
!= NULL
)
350 return ssh_proxy_connect(host
, port
, proxy_command
);
352 /* No proxy command. */
354 memset(&hints
, 0, sizeof(hints
));
355 hints
.ai_family
= family
;
356 hints
.ai_socktype
= SOCK_STREAM
;
357 snprintf(strport
, sizeof strport
, "%u", port
);
358 if ((gaierr
= getaddrinfo(host
, strport
, &hints
, &aitop
)) != 0)
359 fatal("%s: Could not resolve hostname %.100s: %s", __progname
,
360 host
, ssh_gai_strerror(gaierr
));
362 for (attempt
= 0; attempt
< connection_attempts
; attempt
++) {
364 /* Sleep a moment before retrying. */
366 debug("Trying again...");
369 * Loop through addresses for this host, and try each one in
370 * sequence until the connection succeeds.
372 for (ai
= aitop
; ai
; ai
= ai
->ai_next
) {
373 if (ai
->ai_family
!= AF_INET
&& ai
->ai_family
!= AF_INET6
)
375 if (getnameinfo(ai
->ai_addr
, ai
->ai_addrlen
,
376 ntop
, sizeof(ntop
), strport
, sizeof(strport
),
377 NI_NUMERICHOST
|NI_NUMERICSERV
) != 0) {
378 error("ssh_connect: getnameinfo failed");
381 debug("Connecting to %.200s [%.100s] port %s.",
382 host
, ntop
, strport
);
384 /* Create a socket for connecting. */
385 sock
= ssh_create_socket(needpriv
, ai
);
387 /* Any error is already output */
390 if (timeout_connect(sock
, ai
->ai_addr
, ai
->ai_addrlen
,
392 /* Successful connection. */
393 memcpy(hostaddr
, ai
->ai_addr
, ai
->ai_addrlen
);
396 debug("connect to address %s port %s: %s",
397 ntop
, strport
, strerror(errno
));
403 break; /* Successful connection. */
408 /* Return failure if we didn't get a successful connection. */
410 error("ssh: connect to host %s port %s: %s",
411 host
, strport
, strerror(errno
));
415 debug("Connection established.");
417 /* Set SO_KEEPALIVE if requested. */
418 if (want_keepalive
&&
419 setsockopt(sock
, SOL_SOCKET
, SO_KEEPALIVE
, (void *)&on
,
421 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno
));
423 /* Set the connection. */
424 packet_set_connection(sock
, sock
);
430 * Waits for the server identification string, and sends our own
431 * identification string.
434 ssh_exchange_identification(int timeout_ms
)
436 char buf
[256], remote_version
[256]; /* must be same size! */
437 int remote_major
, remote_minor
, mismatch
;
438 int connection_in
= packet_get_connection_in();
439 int connection_out
= packet_get_connection_out();
440 int minor1
= PROTOCOL_MINOR_1
;
443 int fdsetsz
, remaining
, rc
;
444 struct timeval t_start
, t_remaining
;
447 fdsetsz
= howmany(connection_in
+ 1, NFDBITS
) * sizeof(fd_mask
);
448 fdset
= xcalloc(1, fdsetsz
);
450 /* Read other side's version identification. */
451 remaining
= timeout_ms
;
453 for (i
= 0; i
< sizeof(buf
) - 1; i
++) {
454 if (timeout_ms
> 0) {
455 gettimeofday(&t_start
, NULL
);
456 ms_to_timeval(&t_remaining
, remaining
);
457 FD_SET(connection_in
, fdset
);
458 rc
= select(connection_in
+ 1, fdset
, NULL
,
459 fdset
, &t_remaining
);
460 ms_subtract_diff(&t_start
, &remaining
);
461 if (rc
== 0 || remaining
<= 0)
462 fatal("Connection timed out during "
467 fatal("ssh_exchange_identification: "
468 "select: %s", strerror(errno
));
472 len
= atomicio(read
, connection_in
, &buf
[i
], 1);
474 if (len
!= 1 && errno
== EPIPE
)
475 fatal("ssh_exchange_identification: "
476 "Connection closed by remote host");
478 fatal("ssh_exchange_identification: "
479 "read: %.100s", strerror(errno
));
480 if (buf
[i
] == '\r') {
483 continue; /**XXX wait for \n */
485 if (buf
[i
] == '\n') {
490 fatal("ssh_exchange_identification: "
491 "No banner received");
493 buf
[sizeof(buf
) - 1] = 0;
494 if (strncmp(buf
, "SSH-", 4) == 0)
496 debug("ssh_exchange_identification: %s", buf
);
498 server_version_string
= xstrdup(buf
);
502 * Check that the versions match. In future this might accept
503 * several versions and set appropriate flags to handle them.
505 if (sscanf(server_version_string
, "SSH-%d.%d-%[^\n]\n",
506 &remote_major
, &remote_minor
, remote_version
) != 3)
507 fatal("Bad remote protocol version identification: '%.100s'", buf
);
508 debug("Remote protocol version %d.%d, remote software version %.100s",
509 remote_major
, remote_minor
, remote_version
);
511 compat_datafellows(remote_version
);
514 switch (remote_major
) {
516 if (remote_minor
== 99 &&
517 (options
.protocol
& SSH_PROTO_2
) &&
518 !(options
.protocol
& SSH_PROTO_1_PREFERRED
)) {
522 if (!(options
.protocol
& SSH_PROTO_1
)) {
526 if (remote_minor
< 3) {
527 fatal("Remote machine has too old SSH software version.");
528 } else if (remote_minor
== 3 || remote_minor
== 4) {
529 /* We speak 1.3, too. */
532 if (options
.forward_agent
) {
533 logit("Agent forwarding disabled for protocol 1.3");
534 options
.forward_agent
= 0;
539 if (options
.protocol
& SSH_PROTO_2
) {
549 fatal("Protocol major versions differ: %d vs. %d",
550 (options
.protocol
& SSH_PROTO_2
) ? PROTOCOL_MAJOR_2
: PROTOCOL_MAJOR_1
,
552 /* Send our own protocol version identification. */
553 snprintf(buf
, sizeof buf
, "SSH-%d.%d-%.100s\n",
554 compat20
? PROTOCOL_MAJOR_2
: PROTOCOL_MAJOR_1
,
555 compat20
? PROTOCOL_MINOR_2
: minor1
,
557 if (atomicio(vwrite
, connection_out
, buf
, strlen(buf
)) != strlen(buf
))
558 fatal("write: %.100s", strerror(errno
));
559 client_version_string
= xstrdup(buf
);
560 chop(client_version_string
);
561 chop(server_version_string
);
562 debug("Local version string %.100s", client_version_string
);
565 /* defaults to 'no' */
567 confirm(const char *prompt
)
569 const char *msg
, *again
= "Please type 'yes' or 'no': ";
573 if (options
.batch_mode
)
575 for (msg
= prompt
;;msg
= again
) {
576 p
= read_passphrase(msg
, RP_ECHO
);
578 (p
[0] == '\0') || (p
[0] == '\n') ||
579 strncasecmp(p
, "no", 2) == 0)
581 if (p
&& strncasecmp(p
, "yes", 3) == 0)
591 * check whether the supplied host key is valid, return -1 if the key
592 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
598 check_host_key(char *hostname
, struct sockaddr
*hostaddr
, u_short port
,
599 Key
*host_key
, int readonly
, const char *user_hostfile
,
600 const char *system_hostfile
)
603 const char *type
= key_type(host_key
);
604 char *ip
= NULL
, *host
= NULL
;
605 char hostline
[1000], *hostp
, *fp
;
606 HostStatus host_status
;
607 HostStatus ip_status
;
608 int r
, local
= 0, host_ip_differ
= 0;
610 char ntop
[NI_MAXHOST
];
612 int len
, host_line
, ip_line
;
613 const char *host_file
= NULL
, *ip_file
= NULL
;
616 * Force accepting of the host key for loopback/localhost. The
617 * problem is that if the home directory is NFS-mounted to multiple
618 * machines, localhost will refer to a different machine in each of
619 * them, and the user will get bogus HOST_CHANGED warnings. This
620 * essentially disables host authentication for localhost; however,
621 * this is probably not a real problem.
623 /** hostaddr == 0! */
624 switch (hostaddr
->sa_family
) {
626 local
= (ntohl(((struct sockaddr_in
*)hostaddr
)->
627 sin_addr
.s_addr
) >> 24) == IN_LOOPBACKNET
;
628 salen
= sizeof(struct sockaddr_in
);
631 local
= IN6_IS_ADDR_LOOPBACK(
632 &(((struct sockaddr_in6
*)hostaddr
)->sin6_addr
));
633 salen
= sizeof(struct sockaddr_in6
);
637 salen
= sizeof(struct sockaddr_storage
);
640 if (options
.no_host_authentication_for_localhost
== 1 && local
&&
641 options
.host_key_alias
== NULL
) {
642 debug("Forcing accepting of host key for "
643 "loopback/localhost.");
648 * We don't have the remote ip-address for connections
649 * using a proxy command
651 if (options
.proxy_command
== NULL
) {
652 if (getnameinfo(hostaddr
, salen
, ntop
, sizeof(ntop
),
653 NULL
, 0, NI_NUMERICHOST
) != 0)
654 fatal("check_host_key: getnameinfo failed");
655 ip
= put_host_port(ntop
, port
);
657 ip
= xstrdup("<no hostip for proxy command>");
660 * Turn off check_host_ip if the connection is to localhost, via proxy
661 * command or if we don't have a hostname to compare with
663 if (options
.check_host_ip
&& (local
||
664 strcmp(hostname
, ip
) == 0 || options
.proxy_command
!= NULL
))
665 options
.check_host_ip
= 0;
668 * Allow the user to record the key under a different name or
669 * differentiate a non-standard port. This is useful for ssh
670 * tunneling over forwarded connections or if you run multiple
671 * sshd's on different ports on the same machine.
673 if (options
.host_key_alias
!= NULL
) {
674 host
= xstrdup(options
.host_key_alias
);
675 debug("using hostkeyalias: %s", host
);
677 host
= put_host_port(hostname
, port
);
681 * Store the host key from the known host file in here so that we can
682 * compare it with the key for the IP address.
684 file_key
= key_new(host_key
->type
);
687 * Check if the host key is present in the user's list of known
688 * hosts or in the systemwide list.
690 host_file
= user_hostfile
;
691 host_status
= check_host_in_hostfile(host_file
, host
, host_key
,
692 file_key
, &host_line
);
693 if (host_status
== HOST_NEW
) {
694 host_file
= system_hostfile
;
695 host_status
= check_host_in_hostfile(host_file
, host
, host_key
,
696 file_key
, &host_line
);
699 * Also perform check for the ip address, skip the check if we are
700 * localhost or the hostname was an ip address to begin with
702 if (options
.check_host_ip
) {
703 Key
*ip_key
= key_new(host_key
->type
);
705 ip_file
= user_hostfile
;
706 ip_status
= check_host_in_hostfile(ip_file
, ip
, host_key
,
708 if (ip_status
== HOST_NEW
) {
709 ip_file
= system_hostfile
;
710 ip_status
= check_host_in_hostfile(ip_file
, ip
,
711 host_key
, ip_key
, &ip_line
);
713 if (host_status
== HOST_CHANGED
&&
714 (ip_status
!= HOST_CHANGED
|| !key_equal(ip_key
, file_key
)))
719 ip_status
= host_status
;
723 switch (host_status
) {
725 /* The host is known and the key matches. */
726 debug("Host '%.200s' is known and matches the %s host key.",
728 debug("Found key in %s:%d", host_file
, host_line
);
729 if (options
.check_host_ip
&& ip_status
== HOST_NEW
) {
731 logit("%s host key for IP address "
732 "'%.128s' not in list of known hosts.",
734 else if (!add_host_to_hostfile(user_hostfile
, ip
,
735 host_key
, options
.hash_known_hosts
))
736 logit("Failed to add the %s host key for IP "
737 "address '%.128s' to the list of known "
738 "hosts (%.30s).", type
, ip
, user_hostfile
);
740 logit("Warning: Permanently added the %s host "
741 "key for IP address '%.128s' to the list "
742 "of known hosts.", type
, ip
);
746 if (options
.host_key_alias
== NULL
&& port
!= 0 &&
747 port
!= SSH_DEFAULT_PORT
) {
748 debug("checking without port identifier");
749 if (check_host_key(hostname
, hostaddr
, 0, host_key
, 2,
750 user_hostfile
, system_hostfile
) == 0) {
751 debug("found matching key w/out port");
757 /* The host is new. */
758 if (options
.strict_host_key_checking
== 1) {
760 * User has requested strict host key checking. We
761 * will not add the host key automatically. The only
762 * alternative left is to abort.
764 error("No %s host key is known for %.200s and you "
765 "have requested strict checking.", type
, host
);
767 } else if (options
.strict_host_key_checking
== 2) {
768 char msg1
[1024], msg2
[1024];
770 if (show_other_keys(host
, host_key
))
771 snprintf(msg1
, sizeof(msg1
),
772 "\nbut keys of different type are already"
773 " known for this host.");
775 snprintf(msg1
, sizeof(msg1
), ".");
777 fp
= key_fingerprint(host_key
, SSH_FP_MD5
, SSH_FP_HEX
);
779 if (options
.verify_host_key_dns
) {
780 if (matching_host_key_dns
)
781 snprintf(msg2
, sizeof(msg2
),
782 "Matching host key fingerprint"
785 snprintf(msg2
, sizeof(msg2
),
786 "No matching host key fingerprint"
789 snprintf(msg
, sizeof(msg
),
790 "The authenticity of host '%.200s (%s)' can't be "
792 "%s key fingerprint is %s.\n%s"
793 "Are you sure you want to continue connecting "
795 host
, ip
, msg1
, type
, fp
, msg2
);
801 * If not in strict mode, add the key automatically to the
802 * local known_hosts file.
804 if (options
.check_host_ip
&& ip_status
== HOST_NEW
) {
805 snprintf(hostline
, sizeof(hostline
), "%s,%s",
808 if (options
.hash_known_hosts
) {
809 /* Add hash of host and IP separately */
810 r
= add_host_to_hostfile(user_hostfile
, host
,
811 host_key
, options
.hash_known_hosts
) &&
812 add_host_to_hostfile(user_hostfile
, ip
,
813 host_key
, options
.hash_known_hosts
);
815 /* Add unhashed "host,ip" */
816 r
= add_host_to_hostfile(user_hostfile
,
818 options
.hash_known_hosts
);
821 r
= add_host_to_hostfile(user_hostfile
, host
, host_key
,
822 options
.hash_known_hosts
);
827 logit("Failed to add the host to the list of known "
828 "hosts (%.500s).", user_hostfile
);
830 logit("Warning: Permanently added '%.200s' (%s) to the "
831 "list of known hosts.", hostp
, type
);
834 if (readonly
== ROQUIET
)
836 if (options
.check_host_ip
&& host_ip_differ
) {
838 if (ip_status
== HOST_NEW
)
839 key_msg
= "is unknown";
840 else if (ip_status
== HOST_OK
)
841 key_msg
= "is unchanged";
843 key_msg
= "has a different value";
844 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
845 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
846 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
847 error("The %s host key for %s has changed,", type
, host
);
848 error("and the key for the according IP address %s", ip
);
849 error("%s. This could either mean that", key_msg
);
850 error("DNS SPOOFING is happening or the IP address for the host");
851 error("and its host key have changed at the same time.");
852 if (ip_status
!= HOST_NEW
)
853 error("Offending key for IP in %s:%d", ip_file
, ip_line
);
855 /* The host key has changed. */
856 warn_changed_key(host_key
);
857 error("Add correct host key in %.100s to get rid of this message.",
859 error("Offending key in %s:%d", host_file
, host_line
);
862 * If strict host key checking is in use, the user will have
863 * to edit the key manually and we can only abort.
865 if (options
.strict_host_key_checking
) {
866 error("%s host key for %.200s has changed and you have "
867 "requested strict checking.", type
, host
);
872 * If strict host key checking has not been requested, allow
873 * the connection but without MITM-able authentication or
876 if (options
.password_authentication
) {
877 error("Password authentication is disabled to avoid "
878 "man-in-the-middle attacks.");
879 options
.password_authentication
= 0;
881 if (options
.kbd_interactive_authentication
) {
882 error("Keyboard-interactive authentication is disabled"
883 " to avoid man-in-the-middle attacks.");
884 options
.kbd_interactive_authentication
= 0;
885 options
.challenge_response_authentication
= 0;
887 if (options
.challenge_response_authentication
) {
888 error("Challenge/response authentication is disabled"
889 " to avoid man-in-the-middle attacks.");
890 options
.challenge_response_authentication
= 0;
892 if (options
.forward_agent
) {
893 error("Agent forwarding is disabled to avoid "
894 "man-in-the-middle attacks.");
895 options
.forward_agent
= 0;
897 if (options
.forward_x11
) {
898 error("X11 forwarding is disabled to avoid "
899 "man-in-the-middle attacks.");
900 options
.forward_x11
= 0;
902 if (options
.num_local_forwards
> 0 ||
903 options
.num_remote_forwards
> 0) {
904 error("Port forwarding is disabled to avoid "
905 "man-in-the-middle attacks.");
906 options
.num_local_forwards
=
907 options
.num_remote_forwards
= 0;
909 if (options
.tun_open
!= SSH_TUNMODE_NO
) {
910 error("Tunnel forwarding is disabled to avoid "
911 "man-in-the-middle attacks.");
912 options
.tun_open
= SSH_TUNMODE_NO
;
915 * XXX Should permit the user to change to use the new id.
916 * This could be done by converting the host key to an
917 * identifying sentence, tell that the host identifies itself
918 * by that sentence, and ask the user if he/she whishes to
919 * accept the authentication.
923 fatal("internal error");
927 if (options
.check_host_ip
&& host_status
!= HOST_CHANGED
&&
928 ip_status
== HOST_CHANGED
) {
929 snprintf(msg
, sizeof(msg
),
930 "Warning: the %s host key for '%.200s' "
931 "differs from the key for the IP address '%.128s'"
932 "\nOffending key for IP in %s:%d",
933 type
, host
, ip
, ip_file
, ip_line
);
934 if (host_status
== HOST_OK
) {
936 snprintf(msg
+ len
, sizeof(msg
) - len
,
937 "\nMatching host key in %s:%d",
938 host_file
, host_line
);
940 if (options
.strict_host_key_checking
== 1) {
942 error("Exiting, you have requested strict checking.");
944 } else if (options
.strict_host_key_checking
== 2) {
945 strlcat(msg
, "\nAre you sure you want "
946 "to continue connecting (yes/no)? ", sizeof(msg
));
964 /* returns 0 if key verifies or -1 if key does NOT verify */
966 verify_host_key(char *host
, struct sockaddr
*hostaddr
, Key
*host_key
)
971 if (options
.verify_host_key_dns
&&
972 verify_host_key_dns(host
, hostaddr
, host_key
, &flags
) == 0) {
974 if (flags
& DNS_VERIFY_FOUND
) {
976 if (options
.verify_host_key_dns
== 1 &&
977 flags
& DNS_VERIFY_MATCH
&&
978 flags
& DNS_VERIFY_SECURE
)
981 if (flags
& DNS_VERIFY_MATCH
) {
982 matching_host_key_dns
= 1;
984 warn_changed_key(host_key
);
985 error("Update the SSHFP RR in DNS with the new "
986 "host key to get rid of this message.");
991 /* return ok if the key can be found in an old keyfile */
992 if (stat(options
.system_hostfile2
, &st
) == 0 ||
993 stat(options
.user_hostfile2
, &st
) == 0) {
994 if (check_host_key(host
, hostaddr
, options
.port
, host_key
,
995 RDONLY
, options
.user_hostfile2
,
996 options
.system_hostfile2
) == 0)
999 return check_host_key(host
, hostaddr
, options
.port
, host_key
,
1000 RDRW
, options
.user_hostfile
, options
.system_hostfile
);
1004 * Starts a dialog with the server, and authenticates the current user on the
1005 * server. This does not need any extra privileges. The basic connection
1006 * to the server must already have been established before this is called.
1007 * If login fails, this function prints an error and never returns.
1008 * This function does not require super-user privileges.
1011 ssh_login(Sensitive
*sensitive
, const char *orighost
,
1012 struct sockaddr
*hostaddr
, struct passwd
*pw
, int timeout_ms
)
1015 char *server_user
, *local_user
;
1017 local_user
= xstrdup(pw
->pw_name
);
1018 server_user
= options
.user
? options
.user
: local_user
;
1020 /* Convert the user-supplied hostname into all lowercase. */
1021 host
= xstrdup(orighost
);
1022 for (cp
= host
; *cp
; cp
++)
1024 *cp
= (char)tolower(*cp
);
1026 /* Exchange protocol version identification strings with the server. */
1027 ssh_exchange_identification(timeout_ms
);
1029 /* Put the connection into non-blocking mode. */
1030 packet_set_nonblocking();
1033 /* authenticate user */
1035 ssh_kex2(host
, hostaddr
);
1036 ssh_userauth2(local_user
, server_user
, host
, sensitive
);
1038 ssh_kex(host
, hostaddr
);
1039 ssh_userauth1(local_user
, server_user
, host
, sensitive
);
1045 ssh_put_password(char *password
)
1050 if (datafellows
& SSH_BUG_PASSWORDPAD
) {
1051 packet_put_cstring(password
);
1054 size
= roundup(strlen(password
) + 1, 32);
1055 padded
= xcalloc(1, size
);
1056 strlcpy(padded
, password
, size
);
1057 packet_put_string(padded
, size
);
1058 memset(padded
, 0, size
);
1063 show_key_from_file(const char *file
, const char *host
, int keytype
)
1069 found
= key_new(keytype
);
1070 if ((ret
= lookup_key_in_hostfile_by_type(file
, host
,
1071 keytype
, found
, &line
))) {
1072 fp
= key_fingerprint(found
, SSH_FP_MD5
, SSH_FP_HEX
);
1073 logit("WARNING: %s key found for host %s\n"
1075 "%s key fingerprint %s.",
1076 key_type(found
), host
, file
, line
,
1077 key_type(found
), fp
);
1084 /* print all known host keys for a given host, but skip keys of given type */
1086 show_other_keys(const char *host
, Key
*key
)
1088 int type
[] = { KEY_RSA1
, KEY_RSA
, KEY_DSA
, -1};
1091 for (i
= 0; type
[i
] != -1; i
++) {
1092 if (type
[i
] == key
->type
)
1094 if (type
[i
] != KEY_RSA1
&&
1095 show_key_from_file(options
.user_hostfile2
, host
, type
[i
])) {
1099 if (type
[i
] != KEY_RSA1
&&
1100 show_key_from_file(options
.system_hostfile2
, host
, type
[i
])) {
1104 if (show_key_from_file(options
.user_hostfile
, host
, type
[i
])) {
1108 if (show_key_from_file(options
.system_hostfile
, host
, type
[i
])) {
1112 debug2("no key of type %d for host %s", type
[i
], host
);
1118 warn_changed_key(Key
*host_key
)
1121 const char *type
= key_type(host_key
);
1123 fp
= key_fingerprint(host_key
, SSH_FP_MD5
, SSH_FP_HEX
);
1125 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1126 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1127 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1128 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1129 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1130 error("It is also possible that the %s host key has just been changed.", type
);
1131 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1133 error("Please contact your system administrator.");
1139 * Execute a local command
1142 ssh_local_cmd(const char *args
)
1148 if (!options
.permit_local_command
||
1149 args
== NULL
|| !*args
)
1152 if ((shell
= getenv("SHELL")) == NULL
)
1153 shell
= _PATH_BSHELL
;
1157 debug3("Executing %s -c \"%s\"", shell
, args
);
1158 execl(shell
, shell
, "-c", args
, (char *)NULL
);
1159 error("Couldn't execute %s -c \"%s\": %s",
1160 shell
, args
, strerror(errno
));
1162 } else if (pid
== -1)
1163 fatal("fork failed: %.100s", strerror(errno
));
1164 while (waitpid(pid
, &status
, 0) == -1)
1166 fatal("Couldn't wait for child: %s", strerror(errno
));
1168 if (!WIFEXITED(status
))
1171 return (WEXITSTATUS(status
));