2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
7 * information to/from the application to the user client over an encrypted
8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
17 * SSH2 implementation:
18 * Privilege Separation:
20 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
33 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
35 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
36 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
41 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 RCSID("$OpenBSD: sshd.c,v 1.276 2003/08/28 12:54:34 markus Exp $");
47 #include <openssl/dh.h>
48 #include <openssl/bn.h>
49 #include <openssl/md5.h>
50 #include <openssl/rand.h>
51 #ifdef HAVE_SECUREWARE
52 #include <sys/security.h>
73 #include "myproposal.h"
75 #include "pathnames.h"
83 #include "monitor_mm.h"
85 #include "monitor_wrap.h"
86 #include "monitor_fdpass.h"
93 #include <openssl/md5.h>
100 int allow_severity = LOG_INFO;
101 int deny_severity = LOG_WARNING;
108 #ifdef HAVE___PROGNAME
109 extern char *__progname;
114 /* Server configuration options. */
115 ServerOptions options;
117 /* Name of the server configuration file. */
118 char *config_file_name;
121 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
122 * Default value is AF_UNSPEC means both IPv4 and IPv6.
124 int IPv4or6 = AF_UNSPEC;
127 * Debug mode flag. This can be set on the command line. If debug
128 * mode is enabled, extra debugging output will be sent to the system
129 * log, the daemon will not go to background, and will exit after processing
130 * the first connection.
134 /* Flag indicating that the daemon should only test the configuration and keys. */
137 /* Flag indicating that the daemon is being started from inetd. */
140 /* Flag indicating that sshd should not detach and become a daemon. */
141 int no_daemon_flag = 0;
143 /* debug goes to stderr unless inetd_flag is set */
146 /* Saved arguments to main(). */
151 * The sockets that the server is listening; this is used in the SIGHUP
154 #define MAX_LISTEN_SOCKS 16
155 int listen_socks[MAX_LISTEN_SOCKS];
156 int num_listen_socks = 0;
159 * the client's version string, passed by sshd2 in compat mode. if != NULL,
160 * sshd will skip the version-number exchange
162 char *client_version_string = NULL;
163 char *server_version_string = NULL;
165 /* for rekeying XXX fixme */
169 * Any really sensitive data in the application is contained in this
170 * structure. The idea is that this structure could be locked into memory so
171 * that the pages do not get written into swap. However, there are some
172 * problems. The private key contains BIGNUMs, and we do not (in principle)
173 * have access to the internals of them, and locking just the structure is
174 * not very useful. Currently, memory locking is not implemented.
177 Key *server_key; /* ephemeral server key */
178 Key *ssh1_host_key; /* ssh1 host key */
179 Key **host_keys; /* all private host keys */
182 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
186 * Flag indicating whether the RSA server key needs to be regenerated.
187 * Is set in the SIGALRM handler and cleared when the key is regenerated.
189 static volatile sig_atomic_t key_do_regen = 0;
191 /* This is set to true when a signal is received. */
192 static volatile sig_atomic_t received_sighup = 0;
193 static volatile sig_atomic_t received_sigterm = 0;
195 /* session identifier, used by RSA-auth */
196 u_char session_id[16];
199 u_char *session_id2 = NULL;
200 u_int session_id2_len = 0;
202 /* record remote hostname or ip */
203 u_int utmp_len = MAXHOSTNAMELEN;
205 /* options.max_startup sized array of fd ints */
206 int *startup_pipes = NULL;
207 int startup_pipe; /* in child */
209 /* variables used for privilege separation */
211 struct monitor *pmonitor;
213 /* message to be displayed after login */
216 /* Prototypes for various functions defined later in this file. */
217 void destroy_sensitive_data(void);
218 void demote_sensitive_data(void);
220 static void do_ssh1_kex(void);
221 static void do_ssh2_kex(void);
224 * Close all listening sockets
227 close_listen_socks(void)
231 for (i = 0; i < num_listen_socks; i++)
232 close(listen_socks[i]);
233 num_listen_socks = -1;
237 close_startup_pipes(void)
242 for (i = 0; i < options.max_startups; i++)
243 if (startup_pipes[i] != -1)
244 close(startup_pipes[i]);
248 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
249 * the effect is to reread the configuration file (and to regenerate
253 sighup_handler(int sig)
255 int save_errno = errno;
258 signal(SIGHUP, sighup_handler);
263 * Called from the main program after receiving SIGHUP.
264 * Restarts the server.
269 logit("Received SIGHUP; restarting.");
270 close_listen_socks();
271 close_startup_pipes();
272 execv(saved_argv[0], saved_argv);
273 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
279 * Generic signal handler for terminating signals in the master daemon.
282 sigterm_handler(int sig)
284 received_sigterm = sig;
288 * SIGCHLD handler. This is called whenever a child dies. This will then
289 * reap any zombies left by exited children.
292 main_sigchld_handler(int sig)
294 int save_errno = errno;
298 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
299 (pid < 0 && errno == EINTR))
302 signal(SIGCHLD, main_sigchld_handler);
307 * Signal handler for the alarm after the login grace period has expired.
310 grace_alarm_handler(int sig)
312 /* XXX no idea how fix this signal handler */
314 /* Log error and exit. */
315 fatal("Timeout before authentication for %s", get_remote_ipaddr());
319 * Signal handler for the key regeneration alarm. Note that this
320 * alarm only occurs in the daemon waiting for connections, and it does not
321 * do anything with the private key or random state before forking.
322 * Thus there should be no concurrency control/asynchronous execution
326 generate_ephemeral_server_key(void)
331 verbose("Generating %s%d bit RSA key.",
332 sensitive_data.server_key ? "new " : "", options.server_key_bits);
333 if (sensitive_data.server_key != NULL)
334 key_free(sensitive_data.server_key);
335 sensitive_data.server_key = key_generate(KEY_RSA1,
336 options.server_key_bits);
337 verbose("RSA key generation complete.");
339 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
342 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
349 key_regeneration_alarm(int sig)
351 int save_errno = errno;
353 signal(SIGALRM, SIG_DFL);
359 sshd_exchange_identification(int sock_in, int sock_out)
362 int remote_major, remote_minor;
365 char buf[256]; /* Must not be larger than remote_version. */
366 char remote_version[256]; /* Must be at least as big as buf. */
368 if ((options.protocol & SSH_PROTO_1) &&
369 (options.protocol & SSH_PROTO_2)) {
370 major = PROTOCOL_MAJOR_1;
372 } else if (options.protocol & SSH_PROTO_2) {
373 major = PROTOCOL_MAJOR_2;
374 minor = PROTOCOL_MINOR_2;
376 major = PROTOCOL_MAJOR_1;
377 minor = PROTOCOL_MINOR_1;
379 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
380 server_version_string = xstrdup(buf);
382 /* Send our protocol version identification. */
383 if (atomicio(vwrite, sock_out, server_version_string,
384 strlen(server_version_string))
385 != strlen(server_version_string)) {
386 logit("Could not write ident string to %s", get_remote_ipaddr());
390 /* Read other sides version identification. */
391 memset(buf, 0, sizeof(buf));
392 for (i = 0; i < sizeof(buf) - 1; i++) {
393 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
394 logit("Did not receive identification string from %s",
395 get_remote_ipaddr());
398 if (buf[i] == '\r') {
400 /* Kludge for F-Secure Macintosh < 1.0.2 */
402 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
406 if (buf[i] == '\n') {
411 buf[sizeof(buf) - 1] = 0;
412 client_version_string = xstrdup(buf);
415 * Check that the versions match. In future this might accept
416 * several versions and set appropriate flags to handle them.
418 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
419 &remote_major, &remote_minor, remote_version) != 3) {
420 s = "Protocol mismatch.\n";
421 (void) atomicio(vwrite, sock_out, s, strlen(s));
424 logit("Bad protocol version identification '%.100s' from %s",
425 client_version_string, get_remote_ipaddr());
428 debug("Client protocol version %d.%d; client software version %.100s",
429 remote_major, remote_minor, remote_version);
431 compat_datafellows(remote_version);
433 if (datafellows & SSH_BUG_PROBE) {
434 logit("probed from %s with %s. Don't panic.",
435 get_remote_ipaddr(), client_version_string);
439 if (datafellows & SSH_BUG_SCANNER) {
440 logit("scanned from %s with %s. Don't panic.",
441 get_remote_ipaddr(), client_version_string);
446 switch (remote_major) {
448 if (remote_minor == 99) {
449 if (options.protocol & SSH_PROTO_2)
455 if (!(options.protocol & SSH_PROTO_1)) {
459 if (remote_minor < 3) {
460 packet_disconnect("Your ssh version is too old and "
461 "is no longer supported. Please install a newer version.");
462 } else if (remote_minor == 3) {
463 /* note that this disables agent-forwarding */
468 if (options.protocol & SSH_PROTO_2) {
477 chop(server_version_string);
478 debug("Local version string %.200s", server_version_string);
481 s = "Protocol major versions differ.\n";
482 (void) atomicio(vwrite, sock_out, s, strlen(s));
485 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
487 server_version_string, client_version_string);
492 /* Destroy the host and server keys. They will no longer be needed. */
494 destroy_sensitive_data(void)
498 if (sensitive_data.server_key) {
499 key_free(sensitive_data.server_key);
500 sensitive_data.server_key = NULL;
502 for (i = 0; i < options.num_host_key_files; i++) {
503 if (sensitive_data.host_keys[i]) {
504 key_free(sensitive_data.host_keys[i]);
505 sensitive_data.host_keys[i] = NULL;
508 sensitive_data.ssh1_host_key = NULL;
509 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
512 /* Demote private to public keys for network child */
514 demote_sensitive_data(void)
519 if (sensitive_data.server_key) {
520 tmp = key_demote(sensitive_data.server_key);
521 key_free(sensitive_data.server_key);
522 sensitive_data.server_key = tmp;
525 for (i = 0; i < options.num_host_key_files; i++) {
526 if (sensitive_data.host_keys[i]) {
527 tmp = key_demote(sensitive_data.host_keys[i]);
528 key_free(sensitive_data.host_keys[i]);
529 sensitive_data.host_keys[i] = tmp;
530 if (tmp->type == KEY_RSA1)
531 sensitive_data.ssh1_host_key = tmp;
535 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
539 privsep_preauth_child(void)
546 /* Enable challenge-response authentication for privilege separation */
547 privsep_challenge_enable();
549 for (i = 0; i < 256; i++)
550 rnd[i] = arc4random();
551 RAND_seed(rnd, sizeof(rnd));
553 /* Demote the private keys to public keys. */
554 demote_sensitive_data();
556 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
557 fatal("Privilege separation user %s does not exist",
559 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
562 /* Change our root directory */
563 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
564 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
566 if (chdir("/") == -1)
567 fatal("chdir(\"/\"): %s", strerror(errno));
569 /* Drop our privileges */
570 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
573 /* XXX not ready, to heavy after chroot */
574 do_setusercontext(pw);
576 gidset[0] = pw->pw_gid;
577 if (setgroups(1, gidset) < 0)
578 fatal("setgroups: %.100s", strerror(errno));
579 permanently_set_uid(pw);
584 privsep_preauth(void)
586 Authctxt *authctxt = NULL;
590 /* Set up unprivileged child process to deal with network data */
591 pmonitor = monitor_init();
592 /* Store a pointer to the kex for later rekeying */
593 pmonitor->m_pkex = &xxx_kex;
597 fatal("fork of unprivileged child failed");
598 } else if (pid != 0) {
599 fatal_remove_cleanup((void (*) (void *)) packet_close, NULL);
601 debug2("Network child is on pid %ld", (long)pid);
603 close(pmonitor->m_recvfd);
604 authctxt = monitor_child_preauth(pmonitor);
605 close(pmonitor->m_sendfd);
608 monitor_sync(pmonitor);
610 /* Wait for the child's exit status */
611 while (waitpid(pid, &status, 0) < 0)
615 /* Reinstall, since the child has finished */
616 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
622 close(pmonitor->m_sendfd);
624 /* Demote the child */
625 if (getuid() == 0 || geteuid() == 0)
626 privsep_preauth_child();
627 setproctitle("%s", "[net]");
633 privsep_postauth(Authctxt *authctxt)
635 extern Authctxt *x_authctxt;
637 /* XXX - Remote port forwarding */
638 x_authctxt = authctxt;
640 #ifdef DISABLE_FD_PASSING
643 if (authctxt->pw->pw_uid == 0 || options.use_login) {
645 /* File descriptor passing is broken or root login */
646 monitor_apply_keystate(pmonitor);
651 /* Authentication complete */
653 if (startup_pipe != -1) {
658 /* New socket pair */
659 monitor_reinit(pmonitor);
661 pmonitor->m_pid = fork();
662 if (pmonitor->m_pid == -1)
663 fatal("fork of unprivileged child failed");
664 else if (pmonitor->m_pid != 0) {
665 fatal_remove_cleanup((void (*) (void *)) packet_close, NULL);
667 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
668 close(pmonitor->m_recvfd);
669 monitor_child_postauth(pmonitor);
675 close(pmonitor->m_sendfd);
677 /* Demote the private keys to public keys. */
678 demote_sensitive_data();
680 /* Drop privileges */
681 do_setusercontext(authctxt->pw);
683 /* It is safe now to apply the key state */
684 monitor_apply_keystate(pmonitor);
688 list_hostkey_types(void)
695 for (i = 0; i < options.num_host_key_files; i++) {
696 Key *key = sensitive_data.host_keys[i];
702 if (buffer_len(&b) > 0)
703 buffer_append(&b, ",", 1);
704 p = key_ssh_name(key);
705 buffer_append(&b, p, strlen(p));
709 buffer_append(&b, "\0", 1);
710 p = xstrdup(buffer_ptr(&b));
712 debug("list_hostkey_types: %s", p);
717 get_hostkey_by_type(int type)
721 for (i = 0; i < options.num_host_key_files; i++) {
722 Key *key = sensitive_data.host_keys[i];
723 if (key != NULL && key->type == type)
730 get_hostkey_by_index(int ind)
732 if (ind < 0 || ind >= options.num_host_key_files)
734 return (sensitive_data.host_keys[ind]);
738 get_hostkey_index(Key *key)
742 for (i = 0; i < options.num_host_key_files; i++) {
743 if (key == sensitive_data.host_keys[i])
750 * returns 1 if connection should be dropped, 0 otherwise.
751 * dropping starts at connection #max_startups_begin with a probability
752 * of (max_startups_rate/100). the probability increases linearly until
753 * all connections are dropped for startups > max_startups
756 drop_connection(int startups)
760 if (startups < options.max_startups_begin)
762 if (startups >= options.max_startups)
764 if (options.max_startups_rate == 100)
767 p = 100 - options.max_startups_rate;
768 p *= startups - options.max_startups_begin;
769 p /= (double) (options.max_startups - options.max_startups_begin);
770 p += options.max_startups_rate;
772 r = arc4random() / (double) UINT_MAX;
774 debug("drop_connection: p %g, r %g", p, r);
775 return (r < p) ? 1 : 0;
781 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
782 fprintf(stderr, "Usage: %s [options]\n", __progname);
783 fprintf(stderr, "Options:\n");
784 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
785 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
786 fprintf(stderr, " -i Started from inetd\n");
787 fprintf(stderr, " -D Do not fork into daemon mode\n");
788 fprintf(stderr, " -t Only test configuration file and keys\n");
789 fprintf(stderr, " -q Quiet (no logging)\n");
790 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
791 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
792 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
793 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
794 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
795 _PATH_HOST_KEY_FILE);
796 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
797 fprintf(stderr, " -4 Use IPv4 only\n");
798 fprintf(stderr, " -6 Use IPv6 only\n");
799 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
804 * Main program for the daemon.
807 main(int ac, char **av)
811 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
815 struct sockaddr_storage from;
816 const char *remote_ip;
820 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
821 int listen_sock, maxfd;
826 int ret, key_used = 0;
828 #ifdef HAVE_SECUREWARE
829 (void)set_auth_parameters(ac, av);
831 __progname = ssh_get_progname(av[0]);
833 config_file_name = _PATH_SERVER_CONFIG_FILE;
836 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
838 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
839 for (i = 0; i < ac; i++)
840 saved_argv[i] = xstrdup(av[i]);
841 saved_argv[i] = NULL;
843 #ifndef HAVE_SETPROCTITLE
844 /* Prepare for later setproctitle emulation */
845 compat_init_setproctitle(ac, av);
849 /* Initialize configuration options to their default values. */
850 initialize_server_options(&options);
852 /* Parse command-line arguments. */
853 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) {
862 config_file_name = optarg;
865 if (debug_flag == 0) {
867 options.log_level = SYSLOG_LEVEL_DEBUG1;
868 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
884 options.log_level = SYSLOG_LEVEL_QUIET;
887 options.server_key_bits = atoi(optarg);
890 options.ports_from_cmdline = 1;
891 if (options.num_ports >= MAX_PORTS) {
892 fprintf(stderr, "too many ports.\n");
895 options.ports[options.num_ports++] = a2port(optarg);
896 if (options.ports[options.num_ports-1] == 0) {
897 fprintf(stderr, "Bad port number.\n");
902 if ((options.login_grace_time = convtime(optarg)) == -1) {
903 fprintf(stderr, "Invalid login grace time.\n");
908 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
909 fprintf(stderr, "Invalid key regeneration interval.\n");
914 if (options.num_host_key_files >= MAX_HOSTKEYS) {
915 fprintf(stderr, "too many host keys.\n");
918 options.host_key_files[options.num_host_key_files++] = optarg;
924 utmp_len = atoi(optarg);
925 if (utmp_len > MAXHOSTNAMELEN) {
926 fprintf(stderr, "Invalid utmp length.\n");
931 if (process_server_config_line(&options, optarg,
932 "command-line", 0) != 0)
941 SSLeay_add_all_algorithms();
942 channel_set_af(IPv4or6);
945 * Force logging to stderr until we have loaded the private host
946 * key (unless started from inetd)
949 options.log_level == SYSLOG_LEVEL_NOT_SET ?
950 SYSLOG_LEVEL_INFO : options.log_level,
951 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
952 SYSLOG_FACILITY_AUTH : options.log_facility,
953 log_stderr || !inetd_flag);
956 /* Cray can define user privs drop all prives now!
957 * Not needed on PRIV_SU systems!
964 /* Read server configuration options from the configuration file. */
965 read_server_config(&options, config_file_name);
967 /* Fill in default values for those options not explicitly set. */
968 fill_default_server_options(&options);
970 /* Check that there are no remaining arguments. */
972 fprintf(stderr, "Extra argument %s.\n", av[optind]);
976 debug("sshd version %.100s", SSH_VERSION);
978 /* load private host keys */
979 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
981 for (i = 0; i < options.num_host_key_files; i++)
982 sensitive_data.host_keys[i] = NULL;
983 sensitive_data.server_key = NULL;
984 sensitive_data.ssh1_host_key = NULL;
985 sensitive_data.have_ssh1_key = 0;
986 sensitive_data.have_ssh2_key = 0;
988 for (i = 0; i < options.num_host_key_files; i++) {
989 key = key_load_private(options.host_key_files[i], "", NULL);
990 sensitive_data.host_keys[i] = key;
992 error("Could not load host key: %s",
993 options.host_key_files[i]);
994 sensitive_data.host_keys[i] = NULL;
999 sensitive_data.ssh1_host_key = key;
1000 sensitive_data.have_ssh1_key = 1;
1004 sensitive_data.have_ssh2_key = 1;
1007 debug("private host key: #%d type %d %s", i, key->type,
1010 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1011 logit("Disabling protocol version 1. Could not load host key");
1012 options.protocol &= ~SSH_PROTO_1;
1015 /* The GSSAPI key exchange can run without a host key */
1016 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1017 logit("Disabling protocol version 2. Could not load host key");
1018 options.protocol &= ~SSH_PROTO_2;
1021 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1022 logit("sshd: no hostkeys available -- exiting.");
1026 /* Check certain values for sanity. */
1027 if (options.protocol & SSH_PROTO_1) {
1028 if (options.server_key_bits < 512 ||
1029 options.server_key_bits > 32768) {
1030 fprintf(stderr, "Bad server key size.\n");
1034 * Check that server and host key lengths differ sufficiently. This
1035 * is necessary to make double encryption work with rsaref. Oh, I
1036 * hate software patents. I dont know if this can go? Niels
1038 if (options.server_key_bits >
1039 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1040 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1041 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1042 SSH_KEY_BITS_RESERVED) {
1043 options.server_key_bits =
1044 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1045 SSH_KEY_BITS_RESERVED;
1046 debug("Forcing server key to %d bits to make it differ from host key.",
1047 options.server_key_bits);
1055 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1056 fatal("Privilege separation user %s does not exist",
1058 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1059 (S_ISDIR(st.st_mode) == 0))
1060 fatal("Missing privilege separation directory: %s",
1061 _PATH_PRIVSEP_CHROOT_DIR);
1064 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1065 (st.st_uid != getuid () ||
1066 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1068 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1070 fatal("%s must be owned by root and not group or "
1071 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1074 /* Configuration looks good, so exit if in test mode. */
1079 * Clear out any supplemental groups we may have inherited. This
1080 * prevents inadvertent creation of files with bad modes (in the
1081 * portable version at least, it's certainly possible for PAM
1082 * to create a file, and we can't control the code in every
1083 * module which might be used).
1085 if (setgroups(0, NULL) < 0)
1086 debug("setgroups() failed: %.200s", strerror(errno));
1088 /* Initialize the log (it is reinitialized below in case we forked). */
1089 if (debug_flag && !inetd_flag)
1091 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1094 * If not in debugging mode, and not started from inetd, disconnect
1095 * from the controlling terminal, and fork. The original process
1098 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1101 #endif /* TIOCNOTTY */
1102 if (daemon(0, 0) < 0)
1103 fatal("daemon() failed: %.200s", strerror(errno));
1105 /* Disconnect from the controlling tty. */
1107 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1109 (void) ioctl(fd, TIOCNOTTY, NULL);
1112 #endif /* TIOCNOTTY */
1114 /* Reinitialize the log (because of the fork above). */
1115 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1117 /* Initialize the random number generator. */
1120 /* Chdir to the root directory so that the current disk can be
1121 unmounted if desired. */
1124 /* ignore SIGPIPE */
1125 signal(SIGPIPE, SIG_IGN);
1127 /* Start listening for a socket, unless started from inetd. */
1130 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1136 * We intentionally do not close the descriptors 0, 1, and 2
1137 * as our code for setting the descriptors won\'t work if
1138 * ttyfd happens to be one of those.
1140 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1141 if (options.protocol & SSH_PROTO_1)
1142 generate_ephemeral_server_key();
1144 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1145 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1147 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1148 fatal("Too many listen sockets. "
1149 "Enlarge MAX_LISTEN_SOCKS");
1150 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1151 ntop, sizeof(ntop), strport, sizeof(strport),
1152 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1153 error("getnameinfo failed");
1156 /* Create socket for listening. */
1157 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1159 if (listen_sock < 0) {
1160 /* kernel may not support ipv6 */
1161 verbose("socket: %.100s", strerror(errno));
1164 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1165 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1170 * Set socket options.
1171 * Allow local port reuse in TIME_WAIT.
1173 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1174 &on, sizeof(on)) == -1)
1175 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1177 debug("Bind to port %s on %s.", strport, ntop);
1179 /* Bind the socket to the desired port. */
1180 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1182 error("Bind to port %s on %s failed: %.200s.",
1183 strport, ntop, strerror(errno));
1187 listen_socks[num_listen_socks] = listen_sock;
1190 /* Start listening on the port. */
1191 logit("Server listening on %s port %s.", ntop, strport);
1192 if (listen(listen_sock, 5) < 0)
1193 fatal("listen: %.100s", strerror(errno));
1196 freeaddrinfo(options.listen_addrs);
1198 if (!num_listen_socks)
1199 fatal("Cannot bind any address.");
1201 if (options.protocol & SSH_PROTO_1)
1202 generate_ephemeral_server_key();
1205 * Arrange to restart on SIGHUP. The handler needs
1208 signal(SIGHUP, sighup_handler);
1210 signal(SIGTERM, sigterm_handler);
1211 signal(SIGQUIT, sigterm_handler);
1213 /* Arrange SIGCHLD to be caught. */
1214 signal(SIGCHLD, main_sigchld_handler);
1216 /* Write out the pid file after the sigterm handler is setup */
1219 * Record our pid in /var/run/sshd.pid to make it
1220 * easier to kill the correct sshd. We don't want to
1221 * do this before the bind above because the bind will
1222 * fail if there already is a daemon, and this will
1223 * overwrite any old pid in the file.
1225 f = fopen(options.pid_file, "wb");
1227 error("Couldn't create pid file \"%s\": %s",
1228 options.pid_file, strerror(errno));
1230 fprintf(f, "%ld\n", (long) getpid());
1235 /* setup fd set for listen */
1238 for (i = 0; i < num_listen_socks; i++)
1239 if (listen_socks[i] > maxfd)
1240 maxfd = listen_socks[i];
1241 /* pipes connected to unauthenticated childs */
1242 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1243 for (i = 0; i < options.max_startups; i++)
1244 startup_pipes[i] = -1;
1247 * Stay listening for connections until the system crashes or
1248 * the daemon is killed with a signal.
1251 if (received_sighup)
1255 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1256 fdset = (fd_set *)xmalloc(fdsetsz);
1257 memset(fdset, 0, fdsetsz);
1259 for (i = 0; i < num_listen_socks; i++)
1260 FD_SET(listen_socks[i], fdset);
1261 for (i = 0; i < options.max_startups; i++)
1262 if (startup_pipes[i] != -1)
1263 FD_SET(startup_pipes[i], fdset);
1265 /* Wait in select until there is a connection. */
1266 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1267 if (ret < 0 && errno != EINTR)
1268 error("select: %.100s", strerror(errno));
1269 if (received_sigterm) {
1270 logit("Received signal %d; terminating.",
1271 (int) received_sigterm);
1272 close_listen_socks();
1273 unlink(options.pid_file);
1276 if (key_used && key_do_regen) {
1277 generate_ephemeral_server_key();
1284 for (i = 0; i < options.max_startups; i++)
1285 if (startup_pipes[i] != -1 &&
1286 FD_ISSET(startup_pipes[i], fdset)) {
1288 * the read end of the pipe is ready
1289 * if the child has closed the pipe
1290 * after successful authentication
1291 * or if the child has died
1293 close(startup_pipes[i]);
1294 startup_pipes[i] = -1;
1297 for (i = 0; i < num_listen_socks; i++) {
1298 if (!FD_ISSET(listen_socks[i], fdset))
1300 fromlen = sizeof(from);
1301 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1304 if (errno != EINTR && errno != EWOULDBLOCK)
1305 error("accept: %.100s", strerror(errno));
1308 if (fcntl(newsock, F_SETFL, 0) < 0) {
1309 error("newsock del O_NONBLOCK: %s", strerror(errno));
1313 if (drop_connection(startups) == 1) {
1314 debug("drop connection #%d", startups);
1318 if (pipe(startup_p) == -1) {
1323 for (j = 0; j < options.max_startups; j++)
1324 if (startup_pipes[j] == -1) {
1325 startup_pipes[j] = startup_p[0];
1326 if (maxfd < startup_p[0])
1327 maxfd = startup_p[0];
1333 * Got connection. Fork a child to handle it, unless
1334 * we are in debugging mode.
1338 * In debugging mode. Close the listening
1339 * socket, and start processing the
1340 * connection without forking.
1342 debug("Server will not fork when running in debugging mode.");
1343 close_listen_socks();
1351 * Normal production daemon. Fork, and have
1352 * the child process the connection. The
1353 * parent continues listening.
1355 if ((pid = fork()) == 0) {
1357 * Child. Close the listening and max_startup
1358 * sockets. Start using the accepted socket.
1359 * Reinitialize logging (since our pid has
1360 * changed). We break out of the loop to handle
1363 startup_pipe = startup_p[1];
1364 close_startup_pipes();
1365 close_listen_socks();
1368 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1373 /* Parent. Stay in the loop. */
1375 error("fork: %.100s", strerror(errno));
1377 debug("Forked child %ld.", (long)pid);
1379 close(startup_p[1]);
1381 /* Mark that the key has been used (it was "given" to the child). */
1382 if ((options.protocol & SSH_PROTO_1) &&
1384 /* Schedule server key regeneration alarm. */
1385 signal(SIGALRM, key_regeneration_alarm);
1386 alarm(options.key_regeneration_time);
1392 /* Close the new socket (the child is now taking care of it). */
1395 /* child process check (or debug mode) */
1396 if (num_listen_socks < 0)
1401 /* This is the child processing a new connection. */
1404 * Create a new session and process group since the 4.4BSD
1405 * setlogin() affects the entire process group. We don't
1406 * want the child to be able to affect the parent.
1408 #if !defined(SSHD_ACQUIRES_CTTY)
1410 * If setsid is called, on some platforms sshd will later acquire a
1411 * controlling terminal which will result in "could not set
1412 * controlling tty" errors.
1414 if (!debug_flag && !inetd_flag && setsid() < 0)
1415 error("setsid: %.100s", strerror(errno));
1419 * Disable the key regeneration alarm. We will not regenerate the
1420 * key since we are no longer in a position to give it to anyone. We
1421 * will not restart on SIGHUP since it no longer makes sense.
1424 signal(SIGALRM, SIG_DFL);
1425 signal(SIGHUP, SIG_DFL);
1426 signal(SIGTERM, SIG_DFL);
1427 signal(SIGQUIT, SIG_DFL);
1428 signal(SIGCHLD, SIG_DFL);
1429 signal(SIGINT, SIG_DFL);
1431 /* Set keepalives if requested. */
1432 if (options.keepalives &&
1433 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1435 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1438 * Register our connection. This turns encryption off because we do
1441 packet_set_connection(sock_in, sock_out);
1443 remote_port = get_remote_port();
1444 remote_ip = get_remote_ipaddr();
1447 /* Check whether logins are denied from this host. */
1449 struct request_info req;
1451 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1454 if (!hosts_access(&req)) {
1455 debug("Connection refused by tcp wrapper");
1458 fatal("libwrap refuse returns");
1461 #endif /* LIBWRAP */
1463 /* Log the connection. */
1464 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1467 * We don\'t want to listen forever unless the other side
1468 * successfully authenticates itself. So we set up an alarm which is
1469 * cleared after successful authentication. A limit of zero
1470 * indicates no limit. Note that we don\'t set the alarm in debugging
1471 * mode; it is just annoying to have the server exit just when you
1472 * are about to discover the bug.
1474 signal(SIGALRM, grace_alarm_handler);
1476 alarm(options.login_grace_time);
1478 sshd_exchange_identification(sock_in, sock_out);
1479 #if defined(AFS_KRB5)
1480 /* If machine has AFS, set process authentication group. */
1485 #endif /* AFS || AFS_KRB5 */
1487 packet_set_nonblocking();
1489 /* prepare buffers to collect authentication messages */
1490 buffer_init(&loginmsg);
1493 if ((authctxt = privsep_preauth()) != NULL)
1496 /* perform the key exchange */
1497 /* authenticate user and start session */
1500 authctxt = do_authentication2();
1503 authctxt = do_authentication();
1506 * If we use privilege separation, the unprivileged child transfers
1507 * the current keystate and exits
1510 mm_send_keystate(pmonitor);
1516 * In privilege separation, we fork another child and prepare
1517 * file descriptor passing.
1520 privsep_postauth(authctxt);
1521 /* the monitor process [priv] will not return */
1523 destroy_sensitive_data();
1526 /* Perform session preparation. */
1527 do_authenticated(authctxt);
1529 /* The connection has been terminated. */
1530 verbose("Closing connection to %.100s", remote_ip);
1533 if (options.use_pam)
1535 #endif /* USE_PAM */
1546 * Decrypt session_key_int using our private server key and private host key
1547 * (key with larger modulus first).
1550 ssh1_session_key(BIGNUM *session_key_int)
1554 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1555 /* Server key has bigger modulus. */
1556 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1557 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1558 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1559 get_remote_ipaddr(),
1560 BN_num_bits(sensitive_data.server_key->rsa->n),
1561 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1562 SSH_KEY_BITS_RESERVED);
1564 if (rsa_private_decrypt(session_key_int, session_key_int,
1565 sensitive_data.server_key->rsa) <= 0)
1567 if (rsa_private_decrypt(session_key_int, session_key_int,
1568 sensitive_data.ssh1_host_key->rsa) <= 0)
1571 /* Host key has bigger modulus (or they are equal). */
1572 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1573 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1574 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1575 get_remote_ipaddr(),
1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1577 BN_num_bits(sensitive_data.server_key->rsa->n),
1578 SSH_KEY_BITS_RESERVED);
1580 if (rsa_private_decrypt(session_key_int, session_key_int,
1581 sensitive_data.ssh1_host_key->rsa) < 0)
1583 if (rsa_private_decrypt(session_key_int, session_key_int,
1584 sensitive_data.server_key->rsa) < 0)
1597 BIGNUM *session_key_int;
1598 u_char session_key[SSH_SESSION_KEY_LENGTH];
1600 u_int cipher_type, auth_mask, protocol_flags;
1604 * Generate check bytes that the client must send back in the user
1605 * packet in order for it to be accepted; this is used to defy ip
1606 * spoofing attacks. Note that this only works against somebody
1607 * doing IP spoofing from a remote machine; any machine on the local
1608 * network can still see outgoing packets and catch the random
1609 * cookie. This only affects rhosts authentication, and this is one
1610 * of the reasons why it is inherently insecure.
1612 for (i = 0; i < 8; i++) {
1615 cookie[i] = rnd & 0xff;
1620 * Send our public key. We include in the packet 64 bits of random
1621 * data that must be matched in the reply in order to prevent IP
1624 packet_start(SSH_SMSG_PUBLIC_KEY);
1625 for (i = 0; i < 8; i++)
1626 packet_put_char(cookie[i]);
1628 /* Store our public server RSA key. */
1629 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1630 packet_put_bignum(sensitive_data.server_key->rsa->e);
1631 packet_put_bignum(sensitive_data.server_key->rsa->n);
1633 /* Store our public host RSA key. */
1634 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1635 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1636 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1638 /* Put protocol flags. */
1639 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1641 /* Declare which ciphers we support. */
1642 packet_put_int(cipher_mask_ssh1(0));
1644 /* Declare supported authentication types. */
1646 if (options.rhosts_rsa_authentication)
1647 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1648 if (options.rsa_authentication)
1649 auth_mask |= 1 << SSH_AUTH_RSA;
1650 if (options.challenge_response_authentication == 1)
1651 auth_mask |= 1 << SSH_AUTH_TIS;
1652 if (options.password_authentication)
1653 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1654 packet_put_int(auth_mask);
1656 /* Send the packet and wait for it to be sent. */
1658 packet_write_wait();
1660 debug("Sent %d bit server key and %d bit host key.",
1661 BN_num_bits(sensitive_data.server_key->rsa->n),
1662 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1664 /* Read clients reply (cipher type and session key). */
1665 packet_read_expect(SSH_CMSG_SESSION_KEY);
1667 /* Get cipher type and check whether we accept this. */
1668 cipher_type = packet_get_char();
1670 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1671 packet_disconnect("Warning: client selects unsupported cipher.");
1673 /* Get check bytes from the packet. These must match those we
1674 sent earlier with the public key packet. */
1675 for (i = 0; i < 8; i++)
1676 if (cookie[i] != packet_get_char())
1677 packet_disconnect("IP Spoofing check bytes do not match.");
1679 debug("Encryption type: %.200s", cipher_name(cipher_type));
1681 /* Get the encrypted integer. */
1682 if ((session_key_int = BN_new()) == NULL)
1683 fatal("do_ssh1_kex: BN_new failed");
1684 packet_get_bignum(session_key_int);
1686 protocol_flags = packet_get_int();
1687 packet_set_protocol_flags(protocol_flags);
1690 /* Decrypt session_key_int using host/server keys */
1691 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1694 * Extract session key from the decrypted integer. The key is in the
1695 * least significant 256 bits of the integer; the first byte of the
1696 * key is in the highest bits.
1699 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1700 len = BN_num_bytes(session_key_int);
1701 if (len < 0 || len > sizeof(session_key)) {
1702 error("do_connection: bad session key len from %s: "
1703 "session_key_int %d > sizeof(session_key) %lu",
1704 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1707 memset(session_key, 0, sizeof(session_key));
1708 BN_bn2bin(session_key_int,
1709 session_key + sizeof(session_key) - len);
1711 compute_session_id(session_id, cookie,
1712 sensitive_data.ssh1_host_key->rsa->n,
1713 sensitive_data.server_key->rsa->n);
1715 * Xor the first 16 bytes of the session key with the
1718 for (i = 0; i < 16; i++)
1719 session_key[i] ^= session_id[i];
1723 int bytes = BN_num_bytes(session_key_int);
1724 u_char *buf = xmalloc(bytes);
1727 logit("do_connection: generating a fake encryption key");
1728 BN_bn2bin(session_key_int, buf);
1730 MD5_Update(&md, buf, bytes);
1731 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1732 MD5_Final(session_key, &md);
1734 MD5_Update(&md, session_key, 16);
1735 MD5_Update(&md, buf, bytes);
1736 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1737 MD5_Final(session_key + 16, &md);
1738 memset(buf, 0, bytes);
1740 for (i = 0; i < 16; i++)
1741 session_id[i] = session_key[i] ^ session_key[i + 16];
1743 /* Destroy the private and public keys. No longer. */
1744 destroy_sensitive_data();
1747 mm_ssh1_session_id(session_id);
1749 /* Destroy the decrypted integer. It is no longer needed. */
1750 BN_clear_free(session_key_int);
1752 /* Set the session key. From this on all communications will be encrypted. */
1753 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1755 /* Destroy our copy of the session key. It is no longer needed. */
1756 memset(session_key, 0, sizeof(session_key));
1758 debug("Received session key; encryption turned on.");
1760 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1761 packet_start(SSH_SMSG_SUCCESS);
1763 packet_write_wait();
1767 * SSH2 key exchange: diffie-hellman-group1-sha1
1774 if (options.ciphers != NULL) {
1775 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1776 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1778 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1779 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1780 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1781 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1783 if (options.macs != NULL) {
1784 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1785 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1787 if (!options.compression) {
1788 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1789 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1791 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1797 char *newstr = NULL;
1798 orig = myproposal[PROPOSAL_KEX_ALGS];
1800 /* If we don't have a host key, then all of the algorithms
1801 * currently in myproposal are useless */
1802 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
1805 if (options.gss_keyex)
1806 gss = ssh_gssapi_server_mechanisms();
1811 int len = strlen(orig) + strlen(gss) +2;
1812 newstr=xmalloc(len);
1813 snprintf(newstr,len,"%s,%s",gss,orig);
1819 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
1820 host key algorithm, but we're not allowed to advertise it, unless
1821 its the only host key algorithm we're supporting */
1822 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
1823 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
1826 myproposal[PROPOSAL_KEX_ALGS]=newstr;
1828 fatal("No supported key exchange algorithms");
1832 /* start key exchange */
1833 kex = kex_setup(myproposal);
1834 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1835 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1837 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
1840 kex->client_version_string=client_version_string;
1841 kex->server_version_string=server_version_string;
1842 kex->load_host_key=&get_hostkey_by_type;
1843 kex->host_key_index=&get_hostkey_index;
1847 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1849 session_id2 = kex->session_id;
1850 session_id2_len = kex->session_id_len;
1853 /* send 1st encrypted/maced/compressed message */
1854 packet_start(SSH2_MSG_IGNORE);
1855 packet_put_cstring("markus");
1857 packet_write_wait();