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 1.242 2002/05/15 15:47:49 mouring 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"
95 int allow_severity = LOG_INFO;
96 int deny_severity = LOG_WARNING;
103 #ifdef HAVE___PROGNAME
104 extern char *__progname;
109 /* Server configuration options. */
110 ServerOptions options;
112 /* Name of the server configuration file. */
113 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
116 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
117 * Default value is AF_UNSPEC means both IPv4 and IPv6.
120 int IPv4or6 = AF_INET;
122 int IPv4or6 = AF_UNSPEC;
126 * Debug mode flag. This can be set on the command line. If debug
127 * mode is enabled, extra debugging output will be sent to the system
128 * log, the daemon will not go to background, and will exit after processing
129 * the first connection.
133 /* Flag indicating that the daemon should only test the configuration and keys. */
136 /* Flag indicating that the daemon is being started from inetd. */
139 /* Flag indicating that sshd should not detach and become a daemon. */
140 int no_daemon_flag = 0;
142 /* debug goes to stderr unless inetd_flag is set */
145 /* Saved arguments to main(). */
150 * The sockets that the server is listening; this is used in the SIGHUP
153 #define MAX_LISTEN_SOCKS 16
154 int listen_socks[MAX_LISTEN_SOCKS];
155 int num_listen_socks = 0;
158 * the client's version string, passed by sshd2 in compat mode. if != NULL,
159 * sshd will skip the version-number exchange
161 char *client_version_string = NULL;
162 char *server_version_string = NULL;
164 /* for rekeying XXX fixme */
168 * Any really sensitive data in the application is contained in this
169 * structure. The idea is that this structure could be locked into memory so
170 * that the pages do not get written into swap. However, there are some
171 * problems. The private key contains BIGNUMs, and we do not (in principle)
172 * have access to the internals of them, and locking just the structure is
173 * not very useful. Currently, memory locking is not implemented.
176 Key *server_key; /* ephemeral server key */
177 Key *ssh1_host_key; /* ssh1 host key */
178 Key **host_keys; /* all private host keys */
181 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
185 * Flag indicating whether the RSA server key needs to be regenerated.
186 * Is set in the SIGALRM handler and cleared when the key is regenerated.
188 static volatile sig_atomic_t key_do_regen = 0;
190 /* This is set to true when a signal is received. */
191 static volatile sig_atomic_t received_sighup = 0;
192 static volatile sig_atomic_t received_sigterm = 0;
194 /* session identifier, used by RSA-auth */
195 u_char session_id[16];
198 u_char *session_id2 = NULL;
199 int session_id2_len = 0;
201 /* record remote hostname or ip */
202 u_int utmp_len = MAXHOSTNAMELEN;
204 /* options.max_startup sized array of fd ints */
205 int *startup_pipes = NULL;
206 int startup_pipe; /* in child */
208 /* variables used for privilege separation */
209 extern struct monitor *pmonitor;
210 extern int use_privsep;
212 /* Prototypes for various functions defined later in this file. */
213 void destroy_sensitive_data(void);
214 void demote_sensitive_data(void);
216 static void do_ssh1_kex(void);
217 static void do_ssh2_kex(void);
220 * Close all listening sockets
223 close_listen_socks(void)
226 for (i = 0; i < num_listen_socks; i++)
227 close(listen_socks[i]);
228 num_listen_socks = -1;
232 close_startup_pipes(void)
236 for (i = 0; i < options.max_startups; i++)
237 if (startup_pipes[i] != -1)
238 close(startup_pipes[i]);
242 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
243 * the effect is to reread the configuration file (and to regenerate
247 sighup_handler(int sig)
249 int save_errno = errno;
252 signal(SIGHUP, sighup_handler);
257 * Called from the main program after receiving SIGHUP.
258 * Restarts the server.
263 log("Received SIGHUP; restarting.");
264 close_listen_socks();
265 close_startup_pipes();
266 execv(saved_argv[0], saved_argv);
267 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
272 * Generic signal handler for terminating signals in the master daemon.
275 sigterm_handler(int sig)
277 received_sigterm = sig;
281 * SIGCHLD handler. This is called whenever a child dies. This will then
282 * reap any zombies left by exited children.
285 main_sigchld_handler(int sig)
288 int save_errno = errno;
291 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
292 (pid < 0 && errno == EINTR))
295 signal(SIGCHLD, main_sigchld_handler);
300 * Signal handler for the alarm after the login grace period has expired.
303 grace_alarm_handler(int sig)
305 /* XXX no idea how fix this signal handler */
307 /* Close the connection. */
310 /* Log error and exit. */
311 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
315 * Signal handler for the key regeneration alarm. Note that this
316 * alarm only occurs in the daemon waiting for connections, and it does not
317 * do anything with the private key or random state before forking.
318 * Thus there should be no concurrency control/asynchronous execution
322 generate_ephemeral_server_key(void)
327 verbose("Generating %s%d bit RSA key.",
328 sensitive_data.server_key ? "new " : "", options.server_key_bits);
329 if (sensitive_data.server_key != NULL)
330 key_free(sensitive_data.server_key);
331 sensitive_data.server_key = key_generate(KEY_RSA1,
332 options.server_key_bits);
333 verbose("RSA key generation complete.");
335 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
338 sensitive_data.ssh1_cookie[i] = rand & 0xff;
345 key_regeneration_alarm(int sig)
347 int save_errno = errno;
348 signal(SIGALRM, SIG_DFL);
354 sshd_exchange_identification(int sock_in, int sock_out)
357 int remote_major, remote_minor;
360 char buf[256]; /* Must not be larger than remote_version. */
361 char remote_version[256]; /* Must be at least as big as buf. */
363 if ((options.protocol & SSH_PROTO_1) &&
364 (options.protocol & SSH_PROTO_2)) {
365 major = PROTOCOL_MAJOR_1;
367 } else if (options.protocol & SSH_PROTO_2) {
368 major = PROTOCOL_MAJOR_2;
369 minor = PROTOCOL_MINOR_2;
371 major = PROTOCOL_MAJOR_1;
372 minor = PROTOCOL_MINOR_1;
374 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
375 server_version_string = xstrdup(buf);
377 if (client_version_string == NULL) {
378 /* Send our protocol version identification. */
379 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
380 != strlen(server_version_string)) {
381 log("Could not write ident string to %s", get_remote_ipaddr());
385 /* Read other side's version identification. */
386 memset(buf, 0, sizeof(buf));
387 for (i = 0; i < sizeof(buf) - 1; i++) {
388 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
389 log("Did not receive identification string from %s",
390 get_remote_ipaddr());
393 if (buf[i] == '\r') {
395 /* Kludge for F-Secure Macintosh < 1.0.2 */
397 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
401 if (buf[i] == '\n') {
406 buf[sizeof(buf) - 1] = 0;
407 client_version_string = xstrdup(buf);
411 * Check that the versions match. In future this might accept
412 * several versions and set appropriate flags to handle them.
414 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
415 &remote_major, &remote_minor, remote_version) != 3) {
416 s = "Protocol mismatch.\n";
417 (void) atomicio(write, sock_out, s, strlen(s));
420 log("Bad protocol version identification '%.100s' from %s",
421 client_version_string, get_remote_ipaddr());
424 debug("Client protocol version %d.%d; client software version %.100s",
425 remote_major, remote_minor, remote_version);
427 compat_datafellows(remote_version);
429 if (datafellows & SSH_BUG_SCANNER) {
430 log("scanned from %s with %s. Don't panic.",
431 get_remote_ipaddr(), client_version_string);
436 switch (remote_major) {
438 if (remote_minor == 99) {
439 if (options.protocol & SSH_PROTO_2)
445 if (!(options.protocol & SSH_PROTO_1)) {
449 if (remote_minor < 3) {
450 packet_disconnect("Your ssh version is too old and "
451 "is no longer supported. Please install a newer version.");
452 } else if (remote_minor == 3) {
453 /* note that this disables agent-forwarding */
458 if (options.protocol & SSH_PROTO_2) {
467 chop(server_version_string);
468 debug("Local version string %.200s", server_version_string);
471 s = "Protocol major versions differ.\n";
472 (void) atomicio(write, sock_out, s, strlen(s));
475 log("Protocol major versions differ for %s: %.200s vs. %.200s",
477 server_version_string, client_version_string);
483 /* Destroy the host and server keys. They will no longer be needed. */
485 destroy_sensitive_data(void)
489 if (sensitive_data.server_key) {
490 key_free(sensitive_data.server_key);
491 sensitive_data.server_key = NULL;
493 for (i = 0; i < options.num_host_key_files; i++) {
494 if (sensitive_data.host_keys[i]) {
495 key_free(sensitive_data.host_keys[i]);
496 sensitive_data.host_keys[i] = NULL;
499 sensitive_data.ssh1_host_key = NULL;
500 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
503 /* Demote private to public keys for network child */
505 demote_sensitive_data(void)
510 if (sensitive_data.server_key) {
511 tmp = key_demote(sensitive_data.server_key);
512 key_free(sensitive_data.server_key);
513 sensitive_data.server_key = tmp;
516 for (i = 0; i < options.num_host_key_files; i++) {
517 if (sensitive_data.host_keys[i]) {
518 tmp = key_demote(sensitive_data.host_keys[i]);
519 key_free(sensitive_data.host_keys[i]);
520 sensitive_data.host_keys[i] = tmp;
521 if (tmp->type == KEY_RSA1)
522 sensitive_data.ssh1_host_key = tmp;
526 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
530 privsep_preauth_child(void)
536 /* Enable challenge-response authentication for privilege separation */
537 privsep_challenge_enable();
539 for (i = 0; i < 256; i++)
540 rand[i] = arc4random();
541 RAND_seed(rand, sizeof(rand));
543 /* Demote the private keys to public keys. */
544 demote_sensitive_data();
546 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
547 fatal("Privilege separation user %s does not exist",
549 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
552 /* Change our root directory*/
553 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
554 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
556 if (chdir("/") == -1)
557 fatal("chdir(\"/\"): %s", strerror(errno));
559 /* Drop our privileges */
560 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
562 do_setusercontext(pw);
566 privsep_preauth(void)
568 Authctxt *authctxt = NULL;
572 /* Set up unprivileged child process to deal with network data */
573 pmonitor = monitor_init();
574 /* Store a pointer to the kex for later rekeying */
575 pmonitor->m_pkex = &xxx_kex;
579 fatal("fork of unprivileged child failed");
580 } else if (pid != 0) {
581 debug2("Network child is on pid %d", pid);
583 close(pmonitor->m_recvfd);
584 authctxt = monitor_child_preauth(pmonitor);
585 close(pmonitor->m_sendfd);
588 monitor_sync(pmonitor);
590 /* Wait for the child's exit status */
591 while (waitpid(pid, &status, 0) < 0)
598 close(pmonitor->m_sendfd);
600 /* Demote the child */
601 if (getuid() == 0 || geteuid() == 0)
602 privsep_preauth_child();
603 setproctitle("%s", "[net]");
609 privsep_postauth(Authctxt *authctxt)
611 extern Authctxt *x_authctxt;
613 /* XXX - Remote port forwarding */
614 x_authctxt = authctxt;
616 if (authctxt->pw->pw_uid == 0 || options.use_login) {
617 /* File descriptor passing is broken or root login */
618 monitor_apply_keystate(pmonitor);
623 /* Authentication complete */
625 if (startup_pipe != -1) {
630 /* New socket pair */
631 monitor_reinit(pmonitor);
633 pmonitor->m_pid = fork();
634 if (pmonitor->m_pid == -1)
635 fatal("fork of unprivileged child failed");
636 else if (pmonitor->m_pid != 0) {
637 debug2("User child is on pid %d", pmonitor->m_pid);
638 close(pmonitor->m_recvfd);
639 monitor_child_postauth(pmonitor);
645 close(pmonitor->m_sendfd);
647 /* Demote the private keys to public keys. */
648 demote_sensitive_data();
650 /* Drop privileges */
651 do_setusercontext(authctxt->pw);
653 /* It is safe now to apply the key state */
654 monitor_apply_keystate(pmonitor);
658 list_hostkey_types(void)
665 for (i = 0; i < options.num_host_key_files; i++) {
666 Key *key = sensitive_data.host_keys[i];
672 if (buffer_len(&b) > 0)
673 buffer_append(&b, ",", 1);
674 p = key_ssh_name(key);
675 buffer_append(&b, p, strlen(p));
679 buffer_append(&b, "\0", 1);
680 p = xstrdup(buffer_ptr(&b));
682 debug("list_hostkey_types: %s", p);
687 get_hostkey_by_type(int type)
690 for (i = 0; i < options.num_host_key_files; i++) {
691 Key *key = sensitive_data.host_keys[i];
692 if (key != NULL && key->type == type)
699 get_hostkey_by_index(int ind)
701 if (ind < 0 || ind >= options.num_host_key_files)
703 return (sensitive_data.host_keys[ind]);
707 get_hostkey_index(Key *key)
710 for (i = 0; i < options.num_host_key_files; i++) {
711 if (key == sensitive_data.host_keys[i])
718 * returns 1 if connection should be dropped, 0 otherwise.
719 * dropping starts at connection #max_startups_begin with a probability
720 * of (max_startups_rate/100). the probability increases linearly until
721 * all connections are dropped for startups > max_startups
724 drop_connection(int startups)
728 if (startups < options.max_startups_begin)
730 if (startups >= options.max_startups)
732 if (options.max_startups_rate == 100)
735 p = 100 - options.max_startups_rate;
736 p *= startups - options.max_startups_begin;
737 p /= (double) (options.max_startups - options.max_startups_begin);
738 p += options.max_startups_rate;
740 r = arc4random() / (double) UINT_MAX;
742 debug("drop_connection: p %g, r %g", p, r);
743 return (r < p) ? 1 : 0;
749 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
750 fprintf(stderr, "Usage: %s [options]\n", __progname);
751 fprintf(stderr, "Options:\n");
752 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
753 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
754 fprintf(stderr, " -i Started from inetd\n");
755 fprintf(stderr, " -D Do not fork into daemon mode\n");
756 fprintf(stderr, " -t Only test configuration file and keys\n");
757 fprintf(stderr, " -q Quiet (no logging)\n");
758 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
759 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
760 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
761 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
762 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
763 _PATH_HOST_KEY_FILE);
764 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
765 fprintf(stderr, " -4 Use IPv4 only\n");
766 fprintf(stderr, " -6 Use IPv6 only\n");
767 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
772 * Main program for the daemon.
775 main(int ac, char **av)
779 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
783 struct sockaddr_storage from;
784 const char *remote_ip;
787 struct linger linger;
789 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
790 int listen_sock, maxfd;
795 int ret, key_used = 0;
797 #ifdef HAVE_SECUREWARE
798 (void)set_auth_parameters(ac, av);
800 __progname = get_progname(av[0]);
807 /* Initialize configuration options to their default values. */
808 initialize_server_options(&options);
810 /* Parse command-line arguments. */
811 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
820 config_file_name = optarg;
823 if (0 == debug_flag) {
825 options.log_level = SYSLOG_LEVEL_DEBUG1;
826 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
829 fprintf(stderr, "Too high debugging level.\n");
846 options.log_level = SYSLOG_LEVEL_QUIET;
849 options.server_key_bits = atoi(optarg);
852 options.ports_from_cmdline = 1;
853 if (options.num_ports >= MAX_PORTS) {
854 fprintf(stderr, "too many ports.\n");
857 options.ports[options.num_ports++] = a2port(optarg);
858 if (options.ports[options.num_ports-1] == 0) {
859 fprintf(stderr, "Bad port number.\n");
864 if ((options.login_grace_time = convtime(optarg)) == -1) {
865 fprintf(stderr, "Invalid login grace time.\n");
870 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
871 fprintf(stderr, "Invalid key regeneration interval.\n");
876 if (options.num_host_key_files >= MAX_HOSTKEYS) {
877 fprintf(stderr, "too many host keys.\n");
880 options.host_key_files[options.num_host_key_files++] = optarg;
883 client_version_string = optarg;
884 /* only makes sense with inetd_flag, i.e. no listen() */
891 utmp_len = atoi(optarg);
894 if (process_server_config_line(&options, optarg,
895 "command-line", 0) != 0)
904 SSLeay_add_all_algorithms();
905 channel_set_af(IPv4or6);
908 * Force logging to stderr until we have loaded the private host
909 * key (unless started from inetd)
912 options.log_level == SYSLOG_LEVEL_NOT_SET ?
913 SYSLOG_LEVEL_INFO : options.log_level,
914 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
915 SYSLOG_FACILITY_AUTH : options.log_facility,
919 /* Cray can define user privs drop all prives now!
920 * Not needed on PRIV_SU systems!
927 /* Read server configuration options from the configuration file. */
928 read_server_config(&options, config_file_name);
930 /* Fill in default values for those options not explicitly set. */
931 fill_default_server_options(&options);
933 /* Check that there are no remaining arguments. */
935 fprintf(stderr, "Extra argument %s.\n", av[optind]);
939 debug("sshd version %.100s", SSH_VERSION);
941 /* load private host keys */
942 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
943 for (i = 0; i < options.num_host_key_files; i++)
944 sensitive_data.host_keys[i] = NULL;
945 sensitive_data.server_key = NULL;
946 sensitive_data.ssh1_host_key = NULL;
947 sensitive_data.have_ssh1_key = 0;
948 sensitive_data.have_ssh2_key = 0;
950 for (i = 0; i < options.num_host_key_files; i++) {
951 key = key_load_private(options.host_key_files[i], "", NULL);
952 sensitive_data.host_keys[i] = key;
954 error("Could not load host key: %s",
955 options.host_key_files[i]);
956 sensitive_data.host_keys[i] = NULL;
961 sensitive_data.ssh1_host_key = key;
962 sensitive_data.have_ssh1_key = 1;
966 sensitive_data.have_ssh2_key = 1;
969 debug("private host key: #%d type %d %s", i, key->type,
972 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
973 log("Disabling protocol version 1. Could not load host key");
974 options.protocol &= ~SSH_PROTO_1;
977 /* The GSSAPI key exchange can run without a host key */
978 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
979 log("Disabling protocol version 2. Could not load host key");
980 options.protocol &= ~SSH_PROTO_2;
983 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
984 log("sshd: no hostkeys available -- exiting.");
988 /* Check certain values for sanity. */
989 if (options.protocol & SSH_PROTO_1) {
990 if (options.server_key_bits < 512 ||
991 options.server_key_bits > 32768) {
992 fprintf(stderr, "Bad server key size.\n");
996 * Check that server and host key lengths differ sufficiently. This
997 * is necessary to make double encryption work with rsaref. Oh, I
998 * hate software patents. I dont know if this can go? Niels
1000 if (options.server_key_bits >
1001 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
1002 options.server_key_bits <
1003 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1004 options.server_key_bits =
1005 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
1006 debug("Forcing server key to %d bits to make it differ from host key.",
1007 options.server_key_bits);
1011 /* Configuration looks good, so exit if in test mode. */
1017 * Clear out any supplemental groups we may have inherited. This
1018 * prevents inadvertent creation of files with bad modes (in the
1019 * portable version at least, it's certainly possible for PAM
1020 * to create a file, and we can't control the code in every
1021 * module which might be used).
1023 if (setgroups(0, NULL) < 0)
1024 debug("setgroups() failed: %.200s", strerror(errno));
1025 #endif /* !HAVE_CYGWIN */
1027 /* Initialize the log (it is reinitialized below in case we forked). */
1028 if (debug_flag && !inetd_flag)
1030 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1033 * If not in debugging mode, and not started from inetd, disconnect
1034 * from the controlling terminal, and fork. The original process
1037 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1040 #endif /* TIOCNOTTY */
1041 if (daemon(0, 0) < 0)
1042 fatal("daemon() failed: %.200s", strerror(errno));
1044 /* Disconnect from the controlling tty. */
1046 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1048 (void) ioctl(fd, TIOCNOTTY, NULL);
1051 #endif /* TIOCNOTTY */
1053 /* Reinitialize the log (because of the fork above). */
1054 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1056 /* Initialize the random number generator. */
1059 /* Chdir to the root directory so that the current disk can be
1060 unmounted if desired. */
1063 /* ignore SIGPIPE */
1064 signal(SIGPIPE, SIG_IGN);
1066 /* Start listening for a socket, unless started from inetd. */
1069 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1075 * We intentionally do not close the descriptors 0, 1, and 2
1076 * as our code for setting the descriptors won\'t work if
1077 * ttyfd happens to be one of those.
1079 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1080 if (options.protocol & SSH_PROTO_1)
1081 generate_ephemeral_server_key();
1083 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1084 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1086 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1087 fatal("Too many listen sockets. "
1088 "Enlarge MAX_LISTEN_SOCKS");
1089 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1090 ntop, sizeof(ntop), strport, sizeof(strport),
1091 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1092 error("getnameinfo failed");
1095 /* Create socket for listening. */
1096 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
1097 if (listen_sock < 0) {
1098 /* kernel may not support ipv6 */
1099 verbose("socket: %.100s", strerror(errno));
1102 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1103 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1108 * Set socket options. We try to make the port
1109 * reusable and have it close as fast as possible
1110 * without waiting in unnecessary wait states on
1113 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1116 linger.l_linger = 5;
1117 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
1118 &linger, sizeof(linger));
1120 debug("Bind to port %s on %s.", strport, ntop);
1122 /* Bind the socket to the desired port. */
1123 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1125 error("Bind to port %s on %s failed: %.200s.",
1126 strport, ntop, strerror(errno));
1130 listen_socks[num_listen_socks] = listen_sock;
1133 /* Start listening on the port. */
1134 log("Server listening on %s port %s.", ntop, strport);
1135 if (listen(listen_sock, 5) < 0)
1136 fatal("listen: %.100s", strerror(errno));
1139 freeaddrinfo(options.listen_addrs);
1141 if (!num_listen_socks)
1142 fatal("Cannot bind any address.");
1144 if (options.protocol & SSH_PROTO_1)
1145 generate_ephemeral_server_key();
1148 * Arrange to restart on SIGHUP. The handler needs
1151 signal(SIGHUP, sighup_handler);
1153 signal(SIGTERM, sigterm_handler);
1154 signal(SIGQUIT, sigterm_handler);
1156 /* Arrange SIGCHLD to be caught. */
1157 signal(SIGCHLD, main_sigchld_handler);
1159 /* Write out the pid file after the sigterm handler is setup */
1162 * Record our pid in /var/run/sshd.pid to make it
1163 * easier to kill the correct sshd. We don't want to
1164 * do this before the bind above because the bind will
1165 * fail if there already is a daemon, and this will
1166 * overwrite any old pid in the file.
1168 f = fopen(options.pid_file, "wb");
1170 fprintf(f, "%u\n", (u_int) getpid());
1175 /* setup fd set for listen */
1178 for (i = 0; i < num_listen_socks; i++)
1179 if (listen_socks[i] > maxfd)
1180 maxfd = listen_socks[i];
1181 /* pipes connected to unauthenticated childs */
1182 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1183 for (i = 0; i < options.max_startups; i++)
1184 startup_pipes[i] = -1;
1187 * Stay listening for connections until the system crashes or
1188 * the daemon is killed with a signal.
1191 if (received_sighup)
1195 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1196 fdset = (fd_set *)xmalloc(fdsetsz);
1197 memset(fdset, 0, fdsetsz);
1199 for (i = 0; i < num_listen_socks; i++)
1200 FD_SET(listen_socks[i], fdset);
1201 for (i = 0; i < options.max_startups; i++)
1202 if (startup_pipes[i] != -1)
1203 FD_SET(startup_pipes[i], fdset);
1205 /* Wait in select until there is a connection. */
1206 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1207 if (ret < 0 && errno != EINTR)
1208 error("select: %.100s", strerror(errno));
1209 if (received_sigterm) {
1210 log("Received signal %d; terminating.",
1211 (int) received_sigterm);
1212 close_listen_socks();
1213 unlink(options.pid_file);
1216 if (key_used && key_do_regen) {
1217 generate_ephemeral_server_key();
1224 for (i = 0; i < options.max_startups; i++)
1225 if (startup_pipes[i] != -1 &&
1226 FD_ISSET(startup_pipes[i], fdset)) {
1228 * the read end of the pipe is ready
1229 * if the child has closed the pipe
1230 * after successful authentication
1231 * or if the child has died
1233 close(startup_pipes[i]);
1234 startup_pipes[i] = -1;
1237 for (i = 0; i < num_listen_socks; i++) {
1238 if (!FD_ISSET(listen_socks[i], fdset))
1240 fromlen = sizeof(from);
1241 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1244 if (errno != EINTR && errno != EWOULDBLOCK)
1245 error("accept: %.100s", strerror(errno));
1248 if (fcntl(newsock, F_SETFL, 0) < 0) {
1249 error("newsock del O_NONBLOCK: %s", strerror(errno));
1253 if (drop_connection(startups) == 1) {
1254 debug("drop connection #%d", startups);
1258 if (pipe(startup_p) == -1) {
1263 for (j = 0; j < options.max_startups; j++)
1264 if (startup_pipes[j] == -1) {
1265 startup_pipes[j] = startup_p[0];
1266 if (maxfd < startup_p[0])
1267 maxfd = startup_p[0];
1273 * Got connection. Fork a child to handle it, unless
1274 * we are in debugging mode.
1278 * In debugging mode. Close the listening
1279 * socket, and start processing the
1280 * connection without forking.
1282 debug("Server will not fork when running in debugging mode.");
1283 close_listen_socks();
1291 * Normal production daemon. Fork, and have
1292 * the child process the connection. The
1293 * parent continues listening.
1295 if ((pid = fork()) == 0) {
1297 * Child. Close the listening and max_startup
1298 * sockets. Start using the accepted socket.
1299 * Reinitialize logging (since our pid has
1300 * changed). We break out of the loop to handle
1303 startup_pipe = startup_p[1];
1304 close_startup_pipes();
1305 close_listen_socks();
1308 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1313 /* Parent. Stay in the loop. */
1315 error("fork: %.100s", strerror(errno));
1317 debug("Forked child %d.", pid);
1319 close(startup_p[1]);
1321 /* Mark that the key has been used (it was "given" to the child). */
1322 if ((options.protocol & SSH_PROTO_1) &&
1324 /* Schedule server key regeneration alarm. */
1325 signal(SIGALRM, key_regeneration_alarm);
1326 alarm(options.key_regeneration_time);
1332 /* Close the new socket (the child is now taking care of it). */
1335 /* child process check (or debug mode) */
1336 if (num_listen_socks < 0)
1341 /* This is the child processing a new connection. */
1344 * Create a new session and process group since the 4.4BSD
1345 * setlogin() affects the entire process group. We don't
1346 * want the child to be able to affect the parent.
1349 /* XXX: this breaks Solaris */
1351 error("setsid: %.100s", strerror(errno));
1355 * Disable the key regeneration alarm. We will not regenerate the
1356 * key since we are no longer in a position to give it to anyone. We
1357 * will not restart on SIGHUP since it no longer makes sense.
1360 signal(SIGALRM, SIG_DFL);
1361 signal(SIGHUP, SIG_DFL);
1362 signal(SIGTERM, SIG_DFL);
1363 signal(SIGQUIT, SIG_DFL);
1364 signal(SIGCHLD, SIG_DFL);
1365 signal(SIGINT, SIG_DFL);
1368 * Set socket options for the connection. We want the socket to
1369 * close as fast as possible without waiting for anything. If the
1370 * connection is not a socket, these will do nothing.
1372 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1374 linger.l_linger = 5;
1375 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
1377 /* Set keepalives if requested. */
1378 if (options.keepalives &&
1379 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1381 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1384 * Register our connection. This turns encryption off because we do
1387 packet_set_connection(sock_in, sock_out);
1389 remote_port = get_remote_port();
1390 remote_ip = get_remote_ipaddr();
1393 /* Check whether logins are denied from this host. */
1395 struct request_info req;
1397 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1400 if (!hosts_access(&req)) {
1401 debug("Connection refused by tcp wrapper");
1404 fatal("libwrap refuse returns");
1407 #endif /* LIBWRAP */
1409 /* Log the connection. */
1410 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1413 * We don\'t want to listen forever unless the other side
1414 * successfully authenticates itself. So we set up an alarm which is
1415 * cleared after successful authentication. A limit of zero
1416 * indicates no limit. Note that we don\'t set the alarm in debugging
1417 * mode; it is just annoying to have the server exit just when you
1418 * are about to discover the bug.
1420 signal(SIGALRM, grace_alarm_handler);
1422 alarm(options.login_grace_time);
1424 sshd_exchange_identification(sock_in, sock_out);
1426 * Check that the connection comes from a privileged port.
1427 * Rhosts-Authentication only makes sense from priviledged
1428 * programs. Of course, if the intruder has root access on his local
1429 * machine, he can connect from any port. So do not use these
1430 * authentication methods from machines that you do not trust.
1432 if (options.rhosts_authentication &&
1433 (remote_port >= IPPORT_RESERVED ||
1434 remote_port < IPPORT_RESERVED / 2)) {
1435 debug("Rhosts Authentication disabled, "
1436 "originating port %d not trusted.", remote_port);
1437 options.rhosts_authentication = 0;
1439 #if defined(KRB4) && !defined(KRB5)
1440 if (!packet_connection_is_ipv4() &&
1441 options.kerberos_authentication) {
1442 debug("Kerberos Authentication disabled, only available for IPv4.");
1443 options.kerberos_authentication = 0;
1445 #endif /* KRB4 && !KRB5 */
1447 /* If machine has AFS, set process authentication group. */
1454 packet_set_nonblocking();
1457 if ((authctxt = privsep_preauth()) != NULL)
1460 /* perform the key exchange */
1461 /* authenticate user and start session */
1464 authctxt = do_authentication2();
1467 authctxt = do_authentication();
1470 * If we use privilege separation, the unprivileged child transfers
1471 * the current keystate and exits
1474 mm_send_keystate(pmonitor);
1480 * In privilege separation, we fork another child and prepare
1481 * file descriptor passing.
1484 privsep_postauth(authctxt);
1485 /* the monitor process [priv] will not return */
1487 destroy_sensitive_data();
1490 /* Perform session preparation. */
1491 do_authenticated(authctxt);
1493 /* The connection has been terminated. */
1494 verbose("Closing connection to %.100s", remote_ip);
1498 #endif /* USE_PAM */
1509 * Decrypt session_key_int using our private server key and private host key
1510 * (key with larger modulus first).
1513 ssh1_session_key(BIGNUM *session_key_int)
1517 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1518 /* Server key has bigger modulus. */
1519 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1520 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1521 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1522 get_remote_ipaddr(),
1523 BN_num_bits(sensitive_data.server_key->rsa->n),
1524 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1525 SSH_KEY_BITS_RESERVED);
1527 if (rsa_private_decrypt(session_key_int, session_key_int,
1528 sensitive_data.server_key->rsa) <= 0)
1530 if (rsa_private_decrypt(session_key_int, session_key_int,
1531 sensitive_data.ssh1_host_key->rsa) <= 0)
1534 /* Host key has bigger modulus (or they are equal). */
1535 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1536 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1537 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1538 get_remote_ipaddr(),
1539 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1540 BN_num_bits(sensitive_data.server_key->rsa->n),
1541 SSH_KEY_BITS_RESERVED);
1543 if (rsa_private_decrypt(session_key_int, session_key_int,
1544 sensitive_data.ssh1_host_key->rsa) < 0)
1546 if (rsa_private_decrypt(session_key_int, session_key_int,
1547 sensitive_data.server_key->rsa) < 0)
1560 BIGNUM *session_key_int;
1561 u_char session_key[SSH_SESSION_KEY_LENGTH];
1563 u_int cipher_type, auth_mask, protocol_flags;
1567 * Generate check bytes that the client must send back in the user
1568 * packet in order for it to be accepted; this is used to defy ip
1569 * spoofing attacks. Note that this only works against somebody
1570 * doing IP spoofing from a remote machine; any machine on the local
1571 * network can still see outgoing packets and catch the random
1572 * cookie. This only affects rhosts authentication, and this is one
1573 * of the reasons why it is inherently insecure.
1575 for (i = 0; i < 8; i++) {
1577 rand = arc4random();
1578 cookie[i] = rand & 0xff;
1583 * Send our public key. We include in the packet 64 bits of random
1584 * data that must be matched in the reply in order to prevent IP
1587 packet_start(SSH_SMSG_PUBLIC_KEY);
1588 for (i = 0; i < 8; i++)
1589 packet_put_char(cookie[i]);
1591 /* Store our public server RSA key. */
1592 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1593 packet_put_bignum(sensitive_data.server_key->rsa->e);
1594 packet_put_bignum(sensitive_data.server_key->rsa->n);
1596 /* Store our public host RSA key. */
1597 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1598 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1599 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1601 /* Put protocol flags. */
1602 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1604 /* Declare which ciphers we support. */
1605 packet_put_int(cipher_mask_ssh1(0));
1607 /* Declare supported authentication types. */
1609 if (options.rhosts_authentication)
1610 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1611 if (options.rhosts_rsa_authentication)
1612 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1613 if (options.rsa_authentication)
1614 auth_mask |= 1 << SSH_AUTH_RSA;
1615 #if defined(KRB4) || defined(KRB5)
1616 if (options.kerberos_authentication)
1617 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1619 #if defined(AFS) || defined(KRB5)
1620 if (options.kerberos_tgt_passing)
1621 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1624 if (options.afs_token_passing)
1625 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1627 if (options.challenge_response_authentication == 1)
1628 auth_mask |= 1 << SSH_AUTH_TIS;
1629 if (options.password_authentication)
1630 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1631 packet_put_int(auth_mask);
1633 /* Send the packet and wait for it to be sent. */
1635 packet_write_wait();
1637 debug("Sent %d bit server key and %d bit host key.",
1638 BN_num_bits(sensitive_data.server_key->rsa->n),
1639 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1641 /* Read clients reply (cipher type and session key). */
1642 packet_read_expect(SSH_CMSG_SESSION_KEY);
1644 /* Get cipher type and check whether we accept this. */
1645 cipher_type = packet_get_char();
1647 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1648 packet_disconnect("Warning: client selects unsupported cipher.");
1650 /* Get check bytes from the packet. These must match those we
1651 sent earlier with the public key packet. */
1652 for (i = 0; i < 8; i++)
1653 if (cookie[i] != packet_get_char())
1654 packet_disconnect("IP Spoofing check bytes do not match.");
1656 debug("Encryption type: %.200s", cipher_name(cipher_type));
1658 /* Get the encrypted integer. */
1659 if ((session_key_int = BN_new()) == NULL)
1660 fatal("do_ssh1_kex: BN_new failed");
1661 packet_get_bignum(session_key_int);
1663 protocol_flags = packet_get_int();
1664 packet_set_protocol_flags(protocol_flags);
1667 /* Decrypt session_key_int using host/server keys */
1668 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1671 * Extract session key from the decrypted integer. The key is in the
1672 * least significant 256 bits of the integer; the first byte of the
1673 * key is in the highest bits.
1676 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1677 len = BN_num_bytes(session_key_int);
1678 if (len < 0 || len > sizeof(session_key)) {
1679 error("do_connection: bad session key len from %s: "
1680 "session_key_int %d > sizeof(session_key) %lu",
1681 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1684 memset(session_key, 0, sizeof(session_key));
1685 BN_bn2bin(session_key_int,
1686 session_key + sizeof(session_key) - len);
1688 compute_session_id(session_id, cookie,
1689 sensitive_data.ssh1_host_key->rsa->n,
1690 sensitive_data.server_key->rsa->n);
1692 * Xor the first 16 bytes of the session key with the
1695 for (i = 0; i < 16; i++)
1696 session_key[i] ^= session_id[i];
1700 int bytes = BN_num_bytes(session_key_int);
1701 u_char *buf = xmalloc(bytes);
1704 log("do_connection: generating a fake encryption key");
1705 BN_bn2bin(session_key_int, buf);
1707 MD5_Update(&md, buf, bytes);
1708 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1709 MD5_Final(session_key, &md);
1711 MD5_Update(&md, session_key, 16);
1712 MD5_Update(&md, buf, bytes);
1713 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1714 MD5_Final(session_key + 16, &md);
1715 memset(buf, 0, bytes);
1717 for (i = 0; i < 16; i++)
1718 session_id[i] = session_key[i] ^ session_key[i + 16];
1720 /* Destroy the private and public keys. No longer. */
1721 destroy_sensitive_data();
1724 mm_ssh1_session_id(session_id);
1726 /* Destroy the decrypted integer. It is no longer needed. */
1727 BN_clear_free(session_key_int);
1729 /* Set the session key. From this on all communications will be encrypted. */
1730 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1732 /* Destroy our copy of the session key. It is no longer needed. */
1733 memset(session_key, 0, sizeof(session_key));
1735 debug("Received session key; encryption turned on.");
1737 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1738 packet_start(SSH_SMSG_SUCCESS);
1740 packet_write_wait();
1744 * SSH2 key exchange: diffie-hellman-group1-sha1
1751 if (options.ciphers != NULL) {
1752 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1753 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1755 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1756 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1757 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1758 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1760 if (options.macs != NULL) {
1761 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1762 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1764 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1770 char *newstr = NULL;
1771 orig = myproposal[PROPOSAL_KEX_ALGS];
1773 /* If we don't have a host key, then all of the algorithms
1774 * currently in myproposal are useless */
1775 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
1778 if (options.gss_keyex)
1779 gss = ssh_gssapi_mechanisms(1,NULL);
1784 int len = strlen(orig) + strlen(gss) +2;
1785 newstr=xmalloc(len);
1786 snprintf(newstr,len,"%s,%s",gss,orig);
1792 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
1793 host key algorithm, but we're not allowed to advertise it, unless
1794 its the only host key algorithm we're supporting */
1795 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
1796 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
1799 myproposal[PROPOSAL_KEX_ALGS]=newstr;
1801 fatal("No supported key exchange algorithms");
1805 /* start key exchange */
1806 kex = kex_setup(myproposal);
1808 kex->client_version_string=client_version_string;
1809 kex->server_version_string=server_version_string;
1810 kex->load_host_key=&get_hostkey_by_type;
1811 kex->host_key_index=&get_hostkey_index;
1815 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1817 session_id2 = kex->session_id;
1818 session_id2_len = kex->session_id_len;
1821 /* send 1st encrypted/maced/compressed message */
1822 packet_start(SSH2_MSG_IGNORE);
1823 packet_put_cstring("markus");
1825 packet_write_wait();