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 1.290 2004/03/11 10:21:17 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 = NULL;
213 /* message to be displayed after login */
216 /* global authentication context */
217 Authctxt *the_authctxt = NULL;
219 /* Prototypes for various functions defined later in this file. */
220 void destroy_sensitive_data(void);
221 void demote_sensitive_data(void);
223 static void do_ssh1_kex(void);
224 static void do_ssh2_kex(void);
227 * Close all listening sockets
230 close_listen_socks(void)
234 for (i = 0; i < num_listen_socks; i++)
235 close(listen_socks[i]);
236 num_listen_socks = -1;
240 close_startup_pipes(void)
245 for (i = 0; i < options.max_startups; i++)
246 if (startup_pipes[i] != -1)
247 close(startup_pipes[i]);
251 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
252 * the effect is to reread the configuration file (and to regenerate
256 sighup_handler(int sig)
258 int save_errno = errno;
261 signal(SIGHUP, sighup_handler);
266 * Called from the main program after receiving SIGHUP.
267 * Restarts the server.
272 logit("Received SIGHUP; restarting.");
273 close_listen_socks();
274 close_startup_pipes();
275 execv(saved_argv[0], saved_argv);
276 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
282 * Generic signal handler for terminating signals in the master daemon.
285 sigterm_handler(int sig)
287 received_sigterm = sig;
291 * SIGCHLD handler. This is called whenever a child dies. This will then
292 * reap any zombies left by exited children.
295 main_sigchld_handler(int sig)
297 int save_errno = errno;
301 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
302 (pid < 0 && errno == EINTR))
305 signal(SIGCHLD, main_sigchld_handler);
310 * Signal handler for the alarm after the login grace period has expired.
313 grace_alarm_handler(int sig)
315 /* XXX no idea how fix this signal handler */
317 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
318 kill(pmonitor->m_pid, SIGALRM);
320 /* Log error and exit. */
321 fatal("Timeout before authentication for %s", get_remote_ipaddr());
325 * Signal handler for the key regeneration alarm. Note that this
326 * alarm only occurs in the daemon waiting for connections, and it does not
327 * do anything with the private key or random state before forking.
328 * Thus there should be no concurrency control/asynchronous execution
332 generate_ephemeral_server_key(void)
337 verbose("Generating %s%d bit RSA key.",
338 sensitive_data.server_key ? "new " : "", options.server_key_bits);
339 if (sensitive_data.server_key != NULL)
340 key_free(sensitive_data.server_key);
341 sensitive_data.server_key = key_generate(KEY_RSA1,
342 options.server_key_bits);
343 verbose("RSA key generation complete.");
345 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
348 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
355 key_regeneration_alarm(int sig)
357 int save_errno = errno;
359 signal(SIGALRM, SIG_DFL);
365 sshd_exchange_identification(int sock_in, int sock_out)
368 int remote_major, remote_minor;
371 char buf[256]; /* Must not be larger than remote_version. */
372 char remote_version[256]; /* Must be at least as big as buf. */
374 if ((options.protocol & SSH_PROTO_1) &&
375 (options.protocol & SSH_PROTO_2)) {
376 major = PROTOCOL_MAJOR_1;
378 } else if (options.protocol & SSH_PROTO_2) {
379 major = PROTOCOL_MAJOR_2;
380 minor = PROTOCOL_MINOR_2;
382 major = PROTOCOL_MAJOR_1;
383 minor = PROTOCOL_MINOR_1;
385 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
386 server_version_string = xstrdup(buf);
388 /* Send our protocol version identification. */
389 if (atomicio(vwrite, sock_out, server_version_string,
390 strlen(server_version_string))
391 != strlen(server_version_string)) {
392 logit("Could not write ident string to %s", get_remote_ipaddr());
396 /* Read other sides version identification. */
397 memset(buf, 0, sizeof(buf));
398 for (i = 0; i < sizeof(buf) - 1; i++) {
399 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
400 logit("Did not receive identification string from %s",
401 get_remote_ipaddr());
404 if (buf[i] == '\r') {
406 /* Kludge for F-Secure Macintosh < 1.0.2 */
408 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
412 if (buf[i] == '\n') {
417 buf[sizeof(buf) - 1] = 0;
418 client_version_string = xstrdup(buf);
421 * Check that the versions match. In future this might accept
422 * several versions and set appropriate flags to handle them.
424 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
425 &remote_major, &remote_minor, remote_version) != 3) {
426 s = "Protocol mismatch.\n";
427 (void) atomicio(vwrite, sock_out, s, strlen(s));
430 logit("Bad protocol version identification '%.100s' from %s",
431 client_version_string, get_remote_ipaddr());
434 debug("Client protocol version %d.%d; client software version %.100s",
435 remote_major, remote_minor, remote_version);
437 compat_datafellows(remote_version);
439 if (datafellows & SSH_BUG_PROBE) {
440 logit("probed from %s with %s. Don't panic.",
441 get_remote_ipaddr(), client_version_string);
445 if (datafellows & SSH_BUG_SCANNER) {
446 logit("scanned from %s with %s. Don't panic.",
447 get_remote_ipaddr(), client_version_string);
452 switch (remote_major) {
454 if (remote_minor == 99) {
455 if (options.protocol & SSH_PROTO_2)
461 if (!(options.protocol & SSH_PROTO_1)) {
465 if (remote_minor < 3) {
466 packet_disconnect("Your ssh version is too old and "
467 "is no longer supported. Please install a newer version.");
468 } else if (remote_minor == 3) {
469 /* note that this disables agent-forwarding */
474 if (options.protocol & SSH_PROTO_2) {
483 chop(server_version_string);
484 debug("Local version string %.200s", server_version_string);
487 s = "Protocol major versions differ.\n";
488 (void) atomicio(vwrite, sock_out, s, strlen(s));
491 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
493 server_version_string, client_version_string);
498 /* Destroy the host and server keys. They will no longer be needed. */
500 destroy_sensitive_data(void)
504 if (sensitive_data.server_key) {
505 key_free(sensitive_data.server_key);
506 sensitive_data.server_key = NULL;
508 for (i = 0; i < options.num_host_key_files; i++) {
509 if (sensitive_data.host_keys[i]) {
510 key_free(sensitive_data.host_keys[i]);
511 sensitive_data.host_keys[i] = NULL;
514 sensitive_data.ssh1_host_key = NULL;
515 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
518 /* Demote private to public keys for network child */
520 demote_sensitive_data(void)
525 if (sensitive_data.server_key) {
526 tmp = key_demote(sensitive_data.server_key);
527 key_free(sensitive_data.server_key);
528 sensitive_data.server_key = tmp;
531 for (i = 0; i < options.num_host_key_files; i++) {
532 if (sensitive_data.host_keys[i]) {
533 tmp = key_demote(sensitive_data.host_keys[i]);
534 key_free(sensitive_data.host_keys[i]);
535 sensitive_data.host_keys[i] = tmp;
536 if (tmp->type == KEY_RSA1)
537 sensitive_data.ssh1_host_key = tmp;
541 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
545 privsep_preauth_child(void)
552 /* Enable challenge-response authentication for privilege separation */
553 privsep_challenge_enable();
555 for (i = 0; i < 256; i++)
556 rnd[i] = arc4random();
557 RAND_seed(rnd, sizeof(rnd));
559 /* Demote the private keys to public keys. */
560 demote_sensitive_data();
562 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
563 fatal("Privilege separation user %s does not exist",
565 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
568 /* Change our root directory */
569 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
570 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
572 if (chdir("/") == -1)
573 fatal("chdir(\"/\"): %s", strerror(errno));
575 /* Drop our privileges */
576 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
579 /* XXX not ready, too heavy after chroot */
580 do_setusercontext(pw);
582 gidset[0] = pw->pw_gid;
583 if (setgroups(1, gidset) < 0)
584 fatal("setgroups: %.100s", strerror(errno));
585 permanently_set_uid(pw);
590 privsep_preauth(Authctxt *authctxt)
595 /* Set up unprivileged child process to deal with network data */
596 pmonitor = monitor_init();
597 /* Store a pointer to the kex for later rekeying */
598 pmonitor->m_pkex = &xxx_kex;
602 fatal("fork of unprivileged child failed");
603 } else if (pid != 0) {
604 debug2("Network child is on pid %ld", (long)pid);
606 close(pmonitor->m_recvfd);
607 pmonitor->m_pid = pid;
608 monitor_child_preauth(authctxt, pmonitor);
609 close(pmonitor->m_sendfd);
612 monitor_sync(pmonitor);
614 /* Wait for the child's exit status */
615 while (waitpid(pid, &status, 0) < 0)
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 #ifdef DISABLE_FD_PASSING
638 if (authctxt->pw->pw_uid == 0 || options.use_login) {
640 /* File descriptor passing is broken or root login */
641 monitor_apply_keystate(pmonitor);
646 /* Authentication complete */
648 if (startup_pipe != -1) {
653 /* New socket pair */
654 monitor_reinit(pmonitor);
656 pmonitor->m_pid = fork();
657 if (pmonitor->m_pid == -1)
658 fatal("fork of unprivileged child failed");
659 else if (pmonitor->m_pid != 0) {
660 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
661 close(pmonitor->m_recvfd);
662 monitor_child_postauth(pmonitor);
668 close(pmonitor->m_sendfd);
670 /* Demote the private keys to public keys. */
671 demote_sensitive_data();
673 /* Drop privileges */
674 do_setusercontext(authctxt->pw);
676 /* It is safe now to apply the key state */
677 monitor_apply_keystate(pmonitor);
681 list_hostkey_types(void)
689 for (i = 0; i < options.num_host_key_files; i++) {
690 Key *key = sensitive_data.host_keys[i];
696 if (buffer_len(&b) > 0)
697 buffer_append(&b, ",", 1);
698 p = key_ssh_name(key);
699 buffer_append(&b, p, strlen(p));
703 buffer_append(&b, "\0", 1);
704 ret = xstrdup(buffer_ptr(&b));
706 debug("list_hostkey_types: %s", ret);
711 get_hostkey_by_type(int type)
715 for (i = 0; i < options.num_host_key_files; i++) {
716 Key *key = sensitive_data.host_keys[i];
717 if (key != NULL && key->type == type)
724 get_hostkey_by_index(int ind)
726 if (ind < 0 || ind >= options.num_host_key_files)
728 return (sensitive_data.host_keys[ind]);
732 get_hostkey_index(Key *key)
736 for (i = 0; i < options.num_host_key_files; i++) {
737 if (key == sensitive_data.host_keys[i])
744 * returns 1 if connection should be dropped, 0 otherwise.
745 * dropping starts at connection #max_startups_begin with a probability
746 * of (max_startups_rate/100). the probability increases linearly until
747 * all connections are dropped for startups > max_startups
750 drop_connection(int startups)
754 if (startups < options.max_startups_begin)
756 if (startups >= options.max_startups)
758 if (options.max_startups_rate == 100)
761 p = 100 - options.max_startups_rate;
762 p *= startups - options.max_startups_begin;
763 p /= (double) (options.max_startups - options.max_startups_begin);
764 p += options.max_startups_rate;
766 r = arc4random() / (double) UINT_MAX;
768 debug("drop_connection: p %g, r %g", p, r);
769 return (r < p) ? 1 : 0;
775 fprintf(stderr, "%s, %s\n",
776 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
778 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
779 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
785 * Main program for the daemon.
788 main(int ac, char **av)
792 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
796 struct sockaddr_storage from;
797 const char *remote_ip;
801 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
803 int listen_sock, maxfd;
808 int ret, key_used = 0;
810 #ifdef HAVE_SECUREWARE
811 (void)set_auth_parameters(ac, av);
813 __progname = ssh_get_progname(av[0]);
815 config_file_name = _PATH_SERVER_CONFIG_FILE;
818 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
820 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
821 for (i = 0; i < ac; i++)
822 saved_argv[i] = xstrdup(av[i]);
823 saved_argv[i] = NULL;
825 #ifndef HAVE_SETPROCTITLE
826 /* Prepare for later setproctitle emulation */
827 compat_init_setproctitle(ac, av);
831 if (geteuid() == 0 && setgroups(0, NULL) == -1)
832 debug("setgroups(): %.200s", strerror(errno));
834 /* Initialize configuration options to their default values. */
835 initialize_server_options(&options);
837 /* Parse command-line arguments. */
838 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) {
847 config_file_name = optarg;
850 if (debug_flag == 0) {
852 options.log_level = SYSLOG_LEVEL_DEBUG1;
853 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
869 options.log_level = SYSLOG_LEVEL_QUIET;
872 options.server_key_bits = atoi(optarg);
875 options.ports_from_cmdline = 1;
876 if (options.num_ports >= MAX_PORTS) {
877 fprintf(stderr, "too many ports.\n");
880 options.ports[options.num_ports++] = a2port(optarg);
881 if (options.ports[options.num_ports-1] == 0) {
882 fprintf(stderr, "Bad port number.\n");
887 if ((options.login_grace_time = convtime(optarg)) == -1) {
888 fprintf(stderr, "Invalid login grace time.\n");
893 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
894 fprintf(stderr, "Invalid key regeneration interval.\n");
899 if (options.num_host_key_files >= MAX_HOSTKEYS) {
900 fprintf(stderr, "too many host keys.\n");
903 options.host_key_files[options.num_host_key_files++] = optarg;
909 utmp_len = atoi(optarg);
910 if (utmp_len > MAXHOSTNAMELEN) {
911 fprintf(stderr, "Invalid utmp length.\n");
916 line = xstrdup(optarg);
917 if (process_server_config_line(&options, line,
918 "command-line", 0) != 0)
928 SSLeay_add_all_algorithms();
929 channel_set_af(IPv4or6);
932 * Force logging to stderr until we have loaded the private host
933 * key (unless started from inetd)
936 options.log_level == SYSLOG_LEVEL_NOT_SET ?
937 SYSLOG_LEVEL_INFO : options.log_level,
938 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
939 SYSLOG_FACILITY_AUTH : options.log_facility,
940 log_stderr || !inetd_flag);
944 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
947 unsetenv("KRB5CCNAME");
950 /* Cray can define user privs drop all prives now!
951 * Not needed on PRIV_SU systems!
958 /* Read server configuration options from the configuration file. */
959 read_server_config(&options, config_file_name);
961 /* Fill in default values for those options not explicitly set. */
962 fill_default_server_options(&options);
964 /* Check that there are no remaining arguments. */
966 fprintf(stderr, "Extra argument %s.\n", av[optind]);
970 debug("sshd version %.100s", SSH_VERSION);
972 /* load private host keys */
973 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
975 for (i = 0; i < options.num_host_key_files; i++)
976 sensitive_data.host_keys[i] = NULL;
977 sensitive_data.server_key = NULL;
978 sensitive_data.ssh1_host_key = NULL;
979 sensitive_data.have_ssh1_key = 0;
980 sensitive_data.have_ssh2_key = 0;
982 for (i = 0; i < options.num_host_key_files; i++) {
983 key = key_load_private(options.host_key_files[i], "", NULL);
984 sensitive_data.host_keys[i] = key;
986 error("Could not load host key: %s",
987 options.host_key_files[i]);
988 sensitive_data.host_keys[i] = NULL;
993 sensitive_data.ssh1_host_key = key;
994 sensitive_data.have_ssh1_key = 1;
998 sensitive_data.have_ssh2_key = 1;
1001 debug("private host key: #%d type %d %s", i, key->type,
1004 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1005 logit("Disabling protocol version 1. Could not load host key");
1006 options.protocol &= ~SSH_PROTO_1;
1009 /* The GSSAPI key exchange can run without a host key */
1010 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1011 logit("Disabling protocol version 2. Could not load host key");
1012 options.protocol &= ~SSH_PROTO_2;
1015 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1016 logit("sshd: no hostkeys available -- exiting.");
1020 /* Check certain values for sanity. */
1021 if (options.protocol & SSH_PROTO_1) {
1022 if (options.server_key_bits < 512 ||
1023 options.server_key_bits > 32768) {
1024 fprintf(stderr, "Bad server key size.\n");
1028 * Check that server and host key lengths differ sufficiently. This
1029 * is necessary to make double encryption work with rsaref. Oh, I
1030 * hate software patents. I dont know if this can go? Niels
1032 if (options.server_key_bits >
1033 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1034 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1035 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1036 SSH_KEY_BITS_RESERVED) {
1037 options.server_key_bits =
1038 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1039 SSH_KEY_BITS_RESERVED;
1040 debug("Forcing server key to %d bits to make it differ from host key.",
1041 options.server_key_bits);
1049 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1050 fatal("Privilege separation user %s does not exist",
1052 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1053 (S_ISDIR(st.st_mode) == 0))
1054 fatal("Missing privilege separation directory: %s",
1055 _PATH_PRIVSEP_CHROOT_DIR);
1058 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1059 (st.st_uid != getuid () ||
1060 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1062 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1064 fatal("%s must be owned by root and not group or "
1065 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1068 /* Configuration looks good, so exit if in test mode. */
1073 * Clear out any supplemental groups we may have inherited. This
1074 * prevents inadvertent creation of files with bad modes (in the
1075 * portable version at least, it's certainly possible for PAM
1076 * to create a file, and we can't control the code in every
1077 * module which might be used).
1079 if (setgroups(0, NULL) < 0)
1080 debug("setgroups() failed: %.200s", strerror(errno));
1082 /* Initialize the log (it is reinitialized below in case we forked). */
1083 if (debug_flag && !inetd_flag)
1085 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1088 * If not in debugging mode, and not started from inetd, disconnect
1089 * from the controlling terminal, and fork. The original process
1092 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1095 #endif /* TIOCNOTTY */
1096 if (daemon(0, 0) < 0)
1097 fatal("daemon() failed: %.200s", strerror(errno));
1099 /* Disconnect from the controlling tty. */
1101 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1103 (void) ioctl(fd, TIOCNOTTY, NULL);
1106 #endif /* TIOCNOTTY */
1108 /* Reinitialize the log (because of the fork above). */
1109 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1111 /* Initialize the random number generator. */
1114 /* Chdir to the root directory so that the current disk can be
1115 unmounted if desired. */
1118 /* ignore SIGPIPE */
1119 signal(SIGPIPE, SIG_IGN);
1121 /* Start listening for a socket, unless started from inetd. */
1124 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1130 * We intentionally do not close the descriptors 0, 1, and 2
1131 * as our code for setting the descriptors won\'t work if
1132 * ttyfd happens to be one of those.
1134 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1135 if (options.protocol & SSH_PROTO_1)
1136 generate_ephemeral_server_key();
1138 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1139 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1141 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1142 fatal("Too many listen sockets. "
1143 "Enlarge MAX_LISTEN_SOCKS");
1144 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1145 ntop, sizeof(ntop), strport, sizeof(strport),
1146 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1147 error("getnameinfo failed");
1150 /* Create socket for listening. */
1151 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1153 if (listen_sock < 0) {
1154 /* kernel may not support ipv6 */
1155 verbose("socket: %.100s", strerror(errno));
1158 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1159 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1164 * Set socket options.
1165 * Allow local port reuse in TIME_WAIT.
1167 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1168 &on, sizeof(on)) == -1)
1169 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1171 debug("Bind to port %s on %s.", strport, ntop);
1173 /* Bind the socket to the desired port. */
1174 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1176 error("Bind to port %s on %s failed: %.200s.",
1177 strport, ntop, strerror(errno));
1181 listen_socks[num_listen_socks] = listen_sock;
1184 /* Start listening on the port. */
1185 logit("Server listening on %s port %s.", ntop, strport);
1186 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1187 fatal("listen: %.100s", strerror(errno));
1190 freeaddrinfo(options.listen_addrs);
1192 if (!num_listen_socks)
1193 fatal("Cannot bind any address.");
1195 if (options.protocol & SSH_PROTO_1)
1196 generate_ephemeral_server_key();
1199 * Arrange to restart on SIGHUP. The handler needs
1202 signal(SIGHUP, sighup_handler);
1204 signal(SIGTERM, sigterm_handler);
1205 signal(SIGQUIT, sigterm_handler);
1207 /* Arrange SIGCHLD to be caught. */
1208 signal(SIGCHLD, main_sigchld_handler);
1210 /* Write out the pid file after the sigterm handler is setup */
1213 * Record our pid in /var/run/sshd.pid to make it
1214 * easier to kill the correct sshd. We don't want to
1215 * do this before the bind above because the bind will
1216 * fail if there already is a daemon, and this will
1217 * overwrite any old pid in the file.
1219 f = fopen(options.pid_file, "wb");
1221 error("Couldn't create pid file \"%s\": %s",
1222 options.pid_file, strerror(errno));
1224 fprintf(f, "%ld\n", (long) getpid());
1229 /* setup fd set for listen */
1232 for (i = 0; i < num_listen_socks; i++)
1233 if (listen_socks[i] > maxfd)
1234 maxfd = listen_socks[i];
1235 /* pipes connected to unauthenticated childs */
1236 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1237 for (i = 0; i < options.max_startups; i++)
1238 startup_pipes[i] = -1;
1241 * Stay listening for connections until the system crashes or
1242 * the daemon is killed with a signal.
1245 if (received_sighup)
1249 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1250 fdset = (fd_set *)xmalloc(fdsetsz);
1251 memset(fdset, 0, fdsetsz);
1253 for (i = 0; i < num_listen_socks; i++)
1254 FD_SET(listen_socks[i], fdset);
1255 for (i = 0; i < options.max_startups; i++)
1256 if (startup_pipes[i] != -1)
1257 FD_SET(startup_pipes[i], fdset);
1259 /* Wait in select until there is a connection. */
1260 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1261 if (ret < 0 && errno != EINTR)
1262 error("select: %.100s", strerror(errno));
1263 if (received_sigterm) {
1264 logit("Received signal %d; terminating.",
1265 (int) received_sigterm);
1266 close_listen_socks();
1267 unlink(options.pid_file);
1270 if (key_used && key_do_regen) {
1271 generate_ephemeral_server_key();
1278 for (i = 0; i < options.max_startups; i++)
1279 if (startup_pipes[i] != -1 &&
1280 FD_ISSET(startup_pipes[i], fdset)) {
1282 * the read end of the pipe is ready
1283 * if the child has closed the pipe
1284 * after successful authentication
1285 * or if the child has died
1287 close(startup_pipes[i]);
1288 startup_pipes[i] = -1;
1291 for (i = 0; i < num_listen_socks; i++) {
1292 if (!FD_ISSET(listen_socks[i], fdset))
1294 fromlen = sizeof(from);
1295 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1298 if (errno != EINTR && errno != EWOULDBLOCK)
1299 error("accept: %.100s", strerror(errno));
1302 if (fcntl(newsock, F_SETFL, 0) < 0) {
1303 error("newsock del O_NONBLOCK: %s", strerror(errno));
1307 if (drop_connection(startups) == 1) {
1308 debug("drop connection #%d", startups);
1312 if (pipe(startup_p) == -1) {
1317 for (j = 0; j < options.max_startups; j++)
1318 if (startup_pipes[j] == -1) {
1319 startup_pipes[j] = startup_p[0];
1320 if (maxfd < startup_p[0])
1321 maxfd = startup_p[0];
1327 * Got connection. Fork a child to handle it, unless
1328 * we are in debugging mode.
1332 * In debugging mode. Close the listening
1333 * socket, and start processing the
1334 * connection without forking.
1336 debug("Server will not fork when running in debugging mode.");
1337 close_listen_socks();
1345 * Normal production daemon. Fork, and have
1346 * the child process the connection. The
1347 * parent continues listening.
1349 if ((pid = fork()) == 0) {
1351 * Child. Close the listening and max_startup
1352 * sockets. Start using the accepted socket.
1353 * Reinitialize logging (since our pid has
1354 * changed). We break out of the loop to handle
1357 startup_pipe = startup_p[1];
1358 close_startup_pipes();
1359 close_listen_socks();
1362 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1367 /* Parent. Stay in the loop. */
1369 error("fork: %.100s", strerror(errno));
1371 debug("Forked child %ld.", (long)pid);
1373 close(startup_p[1]);
1375 /* Mark that the key has been used (it was "given" to the child). */
1376 if ((options.protocol & SSH_PROTO_1) &&
1378 /* Schedule server key regeneration alarm. */
1379 signal(SIGALRM, key_regeneration_alarm);
1380 alarm(options.key_regeneration_time);
1386 /* Close the new socket (the child is now taking care of it). */
1389 /* child process check (or debug mode) */
1390 if (num_listen_socks < 0)
1395 /* This is the child processing a new connection. */
1396 setproctitle("%s", "[accepted]");
1399 * Create a new session and process group since the 4.4BSD
1400 * setlogin() affects the entire process group. We don't
1401 * want the child to be able to affect the parent.
1403 #if !defined(SSHD_ACQUIRES_CTTY)
1405 * If setsid is called, on some platforms sshd will later acquire a
1406 * controlling terminal which will result in "could not set
1407 * controlling tty" errors.
1409 if (!debug_flag && !inetd_flag && setsid() < 0)
1410 error("setsid: %.100s", strerror(errno));
1414 * Disable the key regeneration alarm. We will not regenerate the
1415 * key since we are no longer in a position to give it to anyone. We
1416 * will not restart on SIGHUP since it no longer makes sense.
1419 signal(SIGALRM, SIG_DFL);
1420 signal(SIGHUP, SIG_DFL);
1421 signal(SIGTERM, SIG_DFL);
1422 signal(SIGQUIT, SIG_DFL);
1423 signal(SIGCHLD, SIG_DFL);
1424 signal(SIGINT, SIG_DFL);
1426 /* Set SO_KEEPALIVE if requested. */
1427 if (options.tcp_keep_alive &&
1428 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1430 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1433 * Register our connection. This turns encryption off because we do
1436 packet_set_connection(sock_in, sock_out);
1438 remote_port = get_remote_port();
1439 remote_ip = get_remote_ipaddr();
1442 /* Check whether logins are denied from this host. */
1444 struct request_info req;
1446 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1449 if (!hosts_access(&req)) {
1450 debug("Connection refused by tcp wrapper");
1453 fatal("libwrap refuse returns");
1456 #endif /* LIBWRAP */
1458 /* Log the connection. */
1459 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1462 * We don\'t want to listen forever unless the other side
1463 * successfully authenticates itself. So we set up an alarm which is
1464 * cleared after successful authentication. A limit of zero
1465 * indicates no limit. Note that we don\'t set the alarm in debugging
1466 * mode; it is just annoying to have the server exit just when you
1467 * are about to discover the bug.
1469 signal(SIGALRM, grace_alarm_handler);
1471 alarm(options.login_grace_time);
1473 sshd_exchange_identification(sock_in, sock_out);
1474 #if defined(AFS_KRB5)
1475 /* If machine has AFS, set process authentication group. */
1480 #endif /* AFS || AFS_KRB5 */
1482 packet_set_nonblocking();
1484 /* prepare buffers to collect authentication messages */
1485 buffer_init(&loginmsg);
1487 /* allocate authentication context */
1488 authctxt = xmalloc(sizeof(*authctxt));
1489 memset(authctxt, 0, sizeof(*authctxt));
1491 /* XXX global for cleanup, access from other modules */
1492 the_authctxt = authctxt;
1495 if (privsep_preauth(authctxt) == 1)
1498 /* perform the key exchange */
1499 /* authenticate user and start session */
1502 do_authentication2(authctxt);
1505 do_authentication(authctxt);
1508 * If we use privilege separation, the unprivileged child transfers
1509 * the current keystate and exits
1512 mm_send_keystate(pmonitor);
1518 * In privilege separation, we fork another child and prepare
1519 * file descriptor passing.
1522 privsep_postauth(authctxt);
1523 /* the monitor process [priv] will not return */
1525 destroy_sensitive_data();
1528 /* Start session. */
1529 do_authenticated(authctxt);
1531 /* The connection has been terminated. */
1532 verbose("Closing connection to %.100s", remote_ip);
1535 if (options.use_pam)
1537 #endif /* USE_PAM */
1548 * Decrypt session_key_int using our private server key and private host key
1549 * (key with larger modulus first).
1552 ssh1_session_key(BIGNUM *session_key_int)
1556 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1557 /* Server key has bigger modulus. */
1558 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1559 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1560 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1561 get_remote_ipaddr(),
1562 BN_num_bits(sensitive_data.server_key->rsa->n),
1563 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1564 SSH_KEY_BITS_RESERVED);
1566 if (rsa_private_decrypt(session_key_int, session_key_int,
1567 sensitive_data.server_key->rsa) <= 0)
1569 if (rsa_private_decrypt(session_key_int, session_key_int,
1570 sensitive_data.ssh1_host_key->rsa) <= 0)
1573 /* Host key has bigger modulus (or they are equal). */
1574 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1575 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1576 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1577 get_remote_ipaddr(),
1578 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1579 BN_num_bits(sensitive_data.server_key->rsa->n),
1580 SSH_KEY_BITS_RESERVED);
1582 if (rsa_private_decrypt(session_key_int, session_key_int,
1583 sensitive_data.ssh1_host_key->rsa) < 0)
1585 if (rsa_private_decrypt(session_key_int, session_key_int,
1586 sensitive_data.server_key->rsa) < 0)
1599 BIGNUM *session_key_int;
1600 u_char session_key[SSH_SESSION_KEY_LENGTH];
1602 u_int cipher_type, auth_mask, protocol_flags;
1606 * Generate check bytes that the client must send back in the user
1607 * packet in order for it to be accepted; this is used to defy ip
1608 * spoofing attacks. Note that this only works against somebody
1609 * doing IP spoofing from a remote machine; any machine on the local
1610 * network can still see outgoing packets and catch the random
1611 * cookie. This only affects rhosts authentication, and this is one
1612 * of the reasons why it is inherently insecure.
1614 for (i = 0; i < 8; i++) {
1617 cookie[i] = rnd & 0xff;
1622 * Send our public key. We include in the packet 64 bits of random
1623 * data that must be matched in the reply in order to prevent IP
1626 packet_start(SSH_SMSG_PUBLIC_KEY);
1627 for (i = 0; i < 8; i++)
1628 packet_put_char(cookie[i]);
1630 /* Store our public server RSA key. */
1631 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1632 packet_put_bignum(sensitive_data.server_key->rsa->e);
1633 packet_put_bignum(sensitive_data.server_key->rsa->n);
1635 /* Store our public host RSA key. */
1636 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1637 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1638 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1640 /* Put protocol flags. */
1641 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1643 /* Declare which ciphers we support. */
1644 packet_put_int(cipher_mask_ssh1(0));
1646 /* Declare supported authentication types. */
1648 if (options.rhosts_rsa_authentication)
1649 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1650 if (options.rsa_authentication)
1651 auth_mask |= 1 << SSH_AUTH_RSA;
1652 if (options.challenge_response_authentication == 1)
1653 auth_mask |= 1 << SSH_AUTH_TIS;
1654 if (options.password_authentication)
1655 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1656 packet_put_int(auth_mask);
1658 /* Send the packet and wait for it to be sent. */
1660 packet_write_wait();
1662 debug("Sent %d bit server key and %d bit host key.",
1663 BN_num_bits(sensitive_data.server_key->rsa->n),
1664 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1666 /* Read clients reply (cipher type and session key). */
1667 packet_read_expect(SSH_CMSG_SESSION_KEY);
1669 /* Get cipher type and check whether we accept this. */
1670 cipher_type = packet_get_char();
1672 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1673 packet_disconnect("Warning: client selects unsupported cipher.");
1675 /* Get check bytes from the packet. These must match those we
1676 sent earlier with the public key packet. */
1677 for (i = 0; i < 8; i++)
1678 if (cookie[i] != packet_get_char())
1679 packet_disconnect("IP Spoofing check bytes do not match.");
1681 debug("Encryption type: %.200s", cipher_name(cipher_type));
1683 /* Get the encrypted integer. */
1684 if ((session_key_int = BN_new()) == NULL)
1685 fatal("do_ssh1_kex: BN_new failed");
1686 packet_get_bignum(session_key_int);
1688 protocol_flags = packet_get_int();
1689 packet_set_protocol_flags(protocol_flags);
1692 /* Decrypt session_key_int using host/server keys */
1693 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1696 * Extract session key from the decrypted integer. The key is in the
1697 * least significant 256 bits of the integer; the first byte of the
1698 * key is in the highest bits.
1701 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1702 len = BN_num_bytes(session_key_int);
1703 if (len < 0 || len > sizeof(session_key)) {
1704 error("do_connection: bad session key len from %s: "
1705 "session_key_int %d > sizeof(session_key) %lu",
1706 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1709 memset(session_key, 0, sizeof(session_key));
1710 BN_bn2bin(session_key_int,
1711 session_key + sizeof(session_key) - len);
1713 compute_session_id(session_id, cookie,
1714 sensitive_data.ssh1_host_key->rsa->n,
1715 sensitive_data.server_key->rsa->n);
1717 * Xor the first 16 bytes of the session key with the
1720 for (i = 0; i < 16; i++)
1721 session_key[i] ^= session_id[i];
1725 int bytes = BN_num_bytes(session_key_int);
1726 u_char *buf = xmalloc(bytes);
1729 logit("do_connection: generating a fake encryption key");
1730 BN_bn2bin(session_key_int, buf);
1732 MD5_Update(&md, buf, bytes);
1733 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1734 MD5_Final(session_key, &md);
1736 MD5_Update(&md, session_key, 16);
1737 MD5_Update(&md, buf, bytes);
1738 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1739 MD5_Final(session_key + 16, &md);
1740 memset(buf, 0, bytes);
1742 for (i = 0; i < 16; i++)
1743 session_id[i] = session_key[i] ^ session_key[i + 16];
1745 /* Destroy the private and public keys. No longer. */
1746 destroy_sensitive_data();
1749 mm_ssh1_session_id(session_id);
1751 /* Destroy the decrypted integer. It is no longer needed. */
1752 BN_clear_free(session_key_int);
1754 /* Set the session key. From this on all communications will be encrypted. */
1755 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1757 /* Destroy our copy of the session key. It is no longer needed. */
1758 memset(session_key, 0, sizeof(session_key));
1760 debug("Received session key; encryption turned on.");
1762 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1763 packet_start(SSH_SMSG_SUCCESS);
1765 packet_write_wait();
1769 * SSH2 key exchange: diffie-hellman-group1-sha1
1776 if (options.ciphers != NULL) {
1777 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1778 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1780 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1781 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1782 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1783 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1785 if (options.macs != NULL) {
1786 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1787 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1789 if (!options.compression) {
1790 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1791 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1793 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1799 char *newstr = NULL;
1800 orig = myproposal[PROPOSAL_KEX_ALGS];
1802 /* If we don't have a host key, then all of the algorithms
1803 * currently in myproposal are useless */
1804 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
1807 if (options.gss_keyex)
1808 gss = ssh_gssapi_server_mechanisms();
1813 int len = strlen(orig) + strlen(gss) +2;
1814 newstr=xmalloc(len);
1815 snprintf(newstr,len,"%s,%s",gss,orig);
1821 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
1822 host key algorithm, but we're not allowed to advertise it, unless
1823 its the only host key algorithm we're supporting */
1824 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
1825 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
1828 myproposal[PROPOSAL_KEX_ALGS]=newstr;
1830 fatal("No supported key exchange algorithms");
1834 /* start key exchange */
1835 kex = kex_setup(myproposal);
1836 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1837 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1839 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
1842 kex->client_version_string=client_version_string;
1843 kex->server_version_string=server_version_string;
1844 kex->load_host_key=&get_hostkey_by_type;
1845 kex->host_key_index=&get_hostkey_index;
1849 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1851 session_id2 = kex->session_id;
1852 session_id2_len = kex->session_id_len;
1855 /* send 1st encrypted/maced/compressed message */
1856 packet_start(SSH2_MSG_IGNORE);
1857 packet_put_cstring("markus");
1859 packet_write_wait();
1864 /* server specific fatal cleanup */
1869 do_cleanup(the_authctxt);