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"
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 = _PATH_SERVER_CONFIG_FILE;
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.
125 int IPv4or6 = AF_INET;
127 int IPv4or6 = AF_UNSPEC;
131 * Debug mode flag. This can be set on the command line. If debug
132 * mode is enabled, extra debugging output will be sent to the system
133 * log, the daemon will not go to background, and will exit after processing
134 * the first connection.
138 /* Flag indicating that the daemon should only test the configuration and keys. */
141 /* Flag indicating that the daemon is being started from inetd. */
144 /* Flag indicating that sshd should not detach and become a daemon. */
145 int no_daemon_flag = 0;
147 /* debug goes to stderr unless inetd_flag is set */
150 /* Saved arguments to main(). */
155 * The sockets that the server is listening; this is used in the SIGHUP
158 #define MAX_LISTEN_SOCKS 16
159 int listen_socks[MAX_LISTEN_SOCKS];
160 int num_listen_socks = 0;
163 * the client's version string, passed by sshd2 in compat mode. if != NULL,
164 * sshd will skip the version-number exchange
166 char *client_version_string = NULL;
167 char *server_version_string = NULL;
169 /* for rekeying XXX fixme */
173 * Any really sensitive data in the application is contained in this
174 * structure. The idea is that this structure could be locked into memory so
175 * that the pages do not get written into swap. However, there are some
176 * problems. The private key contains BIGNUMs, and we do not (in principle)
177 * have access to the internals of them, and locking just the structure is
178 * not very useful. Currently, memory locking is not implemented.
181 Key *server_key; /* ephemeral server key */
182 Key *ssh1_host_key; /* ssh1 host key */
183 Key **host_keys; /* all private host keys */
186 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
190 * Flag indicating whether the RSA server key needs to be regenerated.
191 * Is set in the SIGALRM handler and cleared when the key is regenerated.
193 static volatile sig_atomic_t key_do_regen = 0;
195 /* This is set to true when a signal is received. */
196 static volatile sig_atomic_t received_sighup = 0;
197 static volatile sig_atomic_t received_sigterm = 0;
199 /* session identifier, used by RSA-auth */
200 u_char session_id[16];
203 u_char *session_id2 = NULL;
204 int session_id2_len = 0;
206 /* record remote hostname or ip */
207 u_int utmp_len = MAXHOSTNAMELEN;
209 /* options.max_startup sized array of fd ints */
210 int *startup_pipes = NULL;
211 int startup_pipe; /* in child */
213 /* variables used for privilege separation */
214 extern struct monitor *pmonitor;
215 extern int use_privsep;
217 /* Prototypes for various functions defined later in this file. */
218 void destroy_sensitive_data(void);
219 void demote_sensitive_data(void);
221 static void do_ssh1_kex(void);
222 static void do_ssh2_kex(void);
225 * Close all listening sockets
228 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)
241 for (i = 0; i < options.max_startups; i++)
242 if (startup_pipes[i] != -1)
243 close(startup_pipes[i]);
247 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
248 * the effect is to reread the configuration file (and to regenerate
252 sighup_handler(int sig)
254 int save_errno = errno;
257 signal(SIGHUP, sighup_handler);
262 * Called from the main program after receiving SIGHUP.
263 * Restarts the server.
268 log("Received SIGHUP; restarting.");
269 close_listen_socks();
270 close_startup_pipes();
271 execv(saved_argv[0], saved_argv);
272 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
277 * Generic signal handler for terminating signals in the master daemon.
280 sigterm_handler(int sig)
282 received_sigterm = sig;
286 * SIGCHLD handler. This is called whenever a child dies. This will then
287 * reap any zombies left by exited children.
290 main_sigchld_handler(int sig)
293 int save_errno = errno;
296 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
297 (pid < 0 && errno == EINTR))
300 signal(SIGCHLD, main_sigchld_handler);
305 * Signal handler for the alarm after the login grace period has expired.
308 grace_alarm_handler(int sig)
310 /* XXX no idea how fix this signal handler */
312 /* Close the connection. */
315 /* Log error and exit. */
316 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
320 * Signal handler for the key regeneration alarm. Note that this
321 * alarm only occurs in the daemon waiting for connections, and it does not
322 * do anything with the private key or random state before forking.
323 * Thus there should be no concurrency control/asynchronous execution
327 generate_ephemeral_server_key(void)
332 verbose("Generating %s%d bit RSA key.",
333 sensitive_data.server_key ? "new " : "", options.server_key_bits);
334 if (sensitive_data.server_key != NULL)
335 key_free(sensitive_data.server_key);
336 sensitive_data.server_key = key_generate(KEY_RSA1,
337 options.server_key_bits);
338 verbose("RSA key generation complete.");
340 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
343 sensitive_data.ssh1_cookie[i] = rand & 0xff;
350 key_regeneration_alarm(int sig)
352 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 if (client_version_string == NULL) {
383 /* Send our protocol version identification. */
384 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
385 != strlen(server_version_string)) {
386 log("Could not write ident string to %s", get_remote_ipaddr());
390 /* Read other side's 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 log("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);
416 * Check that the versions match. In future this might accept
417 * several versions and set appropriate flags to handle them.
419 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
420 &remote_major, &remote_minor, remote_version) != 3) {
421 s = "Protocol mismatch.\n";
422 (void) atomicio(write, sock_out, s, strlen(s));
425 log("Bad protocol version identification '%.100s' from %s",
426 client_version_string, get_remote_ipaddr());
429 debug("Client protocol version %d.%d; client software version %.100s",
430 remote_major, remote_minor, remote_version);
432 compat_datafellows(remote_version);
434 if (datafellows & SSH_BUG_SCANNER) {
435 log("scanned from %s with %s. Don't panic.",
436 get_remote_ipaddr(), client_version_string);
441 switch (remote_major) {
443 if (remote_minor == 99) {
444 if (options.protocol & SSH_PROTO_2)
450 if (!(options.protocol & SSH_PROTO_1)) {
454 if (remote_minor < 3) {
455 packet_disconnect("Your ssh version is too old and "
456 "is no longer supported. Please install a newer version.");
457 } else if (remote_minor == 3) {
458 /* note that this disables agent-forwarding */
463 if (options.protocol & SSH_PROTO_2) {
472 chop(server_version_string);
473 debug("Local version string %.200s", server_version_string);
476 s = "Protocol major versions differ.\n";
477 (void) atomicio(write, sock_out, s, strlen(s));
480 log("Protocol major versions differ for %s: %.200s vs. %.200s",
482 server_version_string, client_version_string);
488 /* Destroy the host and server keys. They will no longer be needed. */
490 destroy_sensitive_data(void)
494 if (sensitive_data.server_key) {
495 key_free(sensitive_data.server_key);
496 sensitive_data.server_key = NULL;
498 for (i = 0; i < options.num_host_key_files; i++) {
499 if (sensitive_data.host_keys[i]) {
500 key_free(sensitive_data.host_keys[i]);
501 sensitive_data.host_keys[i] = NULL;
504 sensitive_data.ssh1_host_key = NULL;
505 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
508 /* Demote private to public keys for network child */
510 demote_sensitive_data(void)
515 if (sensitive_data.server_key) {
516 tmp = key_demote(sensitive_data.server_key);
517 key_free(sensitive_data.server_key);
518 sensitive_data.server_key = tmp;
521 for (i = 0; i < options.num_host_key_files; i++) {
522 if (sensitive_data.host_keys[i]) {
523 tmp = key_demote(sensitive_data.host_keys[i]);
524 key_free(sensitive_data.host_keys[i]);
525 sensitive_data.host_keys[i] = tmp;
526 if (tmp->type == KEY_RSA1)
527 sensitive_data.ssh1_host_key = tmp;
531 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
535 privsep_preauth_child(void)
541 /* Enable challenge-response authentication for privilege separation */
542 privsep_challenge_enable();
544 for (i = 0; i < 256; i++)
545 rand[i] = arc4random();
546 RAND_seed(rand, sizeof(rand));
548 /* Demote the private keys to public keys. */
549 demote_sensitive_data();
551 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
552 fatal("Privilege separation user %s does not exist",
554 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
557 /* Change our root directory*/
558 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
559 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
561 if (chdir("/") == -1)
562 fatal("chdir(\"/\"): %s", strerror(errno));
564 /* Drop our privileges */
565 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
567 do_setusercontext(pw);
571 privsep_preauth(void)
573 Authctxt *authctxt = NULL;
577 /* Set up unprivileged child process to deal with network data */
578 pmonitor = monitor_init();
579 /* Store a pointer to the kex for later rekeying */
580 pmonitor->m_pkex = &xxx_kex;
584 fatal("fork of unprivileged child failed");
585 } else if (pid != 0) {
586 debug2("Network child is on pid %d", pid);
588 close(pmonitor->m_recvfd);
589 authctxt = monitor_child_preauth(pmonitor);
590 close(pmonitor->m_sendfd);
593 monitor_sync(pmonitor);
595 /* Wait for the child's exit status */
596 while (waitpid(pid, &status, 0) < 0)
603 close(pmonitor->m_sendfd);
605 /* Demote the child */
606 if (getuid() == 0 || geteuid() == 0)
607 privsep_preauth_child();
608 setproctitle("%s", "[net]");
614 privsep_postauth(Authctxt *authctxt)
616 extern Authctxt *x_authctxt;
618 /* XXX - Remote port forwarding */
619 x_authctxt = authctxt;
621 if (authctxt->pw->pw_uid == 0 || options.use_login) {
622 /* File descriptor passing is broken or root login */
623 monitor_apply_keystate(pmonitor);
628 /* Authentication complete */
630 if (startup_pipe != -1) {
635 /* New socket pair */
636 monitor_reinit(pmonitor);
638 pmonitor->m_pid = fork();
639 if (pmonitor->m_pid == -1)
640 fatal("fork of unprivileged child failed");
641 else if (pmonitor->m_pid != 0) {
642 debug2("User child is on pid %d", pmonitor->m_pid);
643 close(pmonitor->m_recvfd);
644 monitor_child_postauth(pmonitor);
650 close(pmonitor->m_sendfd);
652 /* Demote the private keys to public keys. */
653 demote_sensitive_data();
655 /* Drop privileges */
656 do_setusercontext(authctxt->pw);
658 /* It is safe now to apply the key state */
659 monitor_apply_keystate(pmonitor);
663 list_hostkey_types(void)
670 for (i = 0; i < options.num_host_key_files; i++) {
671 Key *key = sensitive_data.host_keys[i];
677 if (buffer_len(&b) > 0)
678 buffer_append(&b, ",", 1);
679 p = key_ssh_name(key);
680 buffer_append(&b, p, strlen(p));
684 buffer_append(&b, "\0", 1);
685 p = xstrdup(buffer_ptr(&b));
687 debug("list_hostkey_types: %s", p);
692 get_hostkey_by_type(int type)
695 for (i = 0; i < options.num_host_key_files; i++) {
696 Key *key = sensitive_data.host_keys[i];
697 if (key != NULL && key->type == type)
704 get_hostkey_by_index(int ind)
706 if (ind < 0 || ind >= options.num_host_key_files)
708 return (sensitive_data.host_keys[ind]);
712 get_hostkey_index(Key *key)
715 for (i = 0; i < options.num_host_key_files; i++) {
716 if (key == sensitive_data.host_keys[i])
723 * returns 1 if connection should be dropped, 0 otherwise.
724 * dropping starts at connection #max_startups_begin with a probability
725 * of (max_startups_rate/100). the probability increases linearly until
726 * all connections are dropped for startups > max_startups
729 drop_connection(int startups)
733 if (startups < options.max_startups_begin)
735 if (startups >= options.max_startups)
737 if (options.max_startups_rate == 100)
740 p = 100 - options.max_startups_rate;
741 p *= startups - options.max_startups_begin;
742 p /= (double) (options.max_startups - options.max_startups_begin);
743 p += options.max_startups_rate;
745 r = arc4random() / (double) UINT_MAX;
747 debug("drop_connection: p %g, r %g", p, r);
748 return (r < p) ? 1 : 0;
754 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
755 fprintf(stderr, "Usage: %s [options]\n", __progname);
756 fprintf(stderr, "Options:\n");
757 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
758 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
759 fprintf(stderr, " -i Started from inetd\n");
760 fprintf(stderr, " -D Do not fork into daemon mode\n");
761 fprintf(stderr, " -t Only test configuration file and keys\n");
762 fprintf(stderr, " -q Quiet (no logging)\n");
763 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
764 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
765 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
766 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
767 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
768 _PATH_HOST_KEY_FILE);
769 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
770 fprintf(stderr, " -4 Use IPv4 only\n");
771 fprintf(stderr, " -6 Use IPv6 only\n");
772 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
777 * Main program for the daemon.
780 main(int ac, char **av)
784 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
788 struct sockaddr_storage from;
789 const char *remote_ip;
792 struct linger linger;
794 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
795 int listen_sock, maxfd;
800 int ret, key_used = 0;
802 #ifdef HAVE_SECUREWARE
803 (void)set_auth_parameters(ac, av);
805 __progname = get_progname(av[0]);
812 /* Initialize configuration options to their default values. */
813 initialize_server_options(&options);
815 /* Parse command-line arguments. */
816 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
825 config_file_name = optarg;
828 if (0 == debug_flag) {
830 options.log_level = SYSLOG_LEVEL_DEBUG1;
831 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
834 fprintf(stderr, "Too high debugging level.\n");
851 options.log_level = SYSLOG_LEVEL_QUIET;
854 options.server_key_bits = atoi(optarg);
857 options.ports_from_cmdline = 1;
858 if (options.num_ports >= MAX_PORTS) {
859 fprintf(stderr, "too many ports.\n");
862 options.ports[options.num_ports++] = a2port(optarg);
863 if (options.ports[options.num_ports-1] == 0) {
864 fprintf(stderr, "Bad port number.\n");
869 if ((options.login_grace_time = convtime(optarg)) == -1) {
870 fprintf(stderr, "Invalid login grace time.\n");
875 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
876 fprintf(stderr, "Invalid key regeneration interval.\n");
881 if (options.num_host_key_files >= MAX_HOSTKEYS) {
882 fprintf(stderr, "too many host keys.\n");
885 options.host_key_files[options.num_host_key_files++] = optarg;
888 client_version_string = optarg;
889 /* only makes sense with inetd_flag, i.e. no listen() */
896 utmp_len = atoi(optarg);
899 if (process_server_config_line(&options, optarg,
900 "command-line", 0) != 0)
909 SSLeay_add_all_algorithms();
910 channel_set_af(IPv4or6);
913 * Force logging to stderr until we have loaded the private host
914 * key (unless started from inetd)
917 options.log_level == SYSLOG_LEVEL_NOT_SET ?
918 SYSLOG_LEVEL_INFO : options.log_level,
919 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
920 SYSLOG_FACILITY_AUTH : options.log_facility,
924 /* Cray can define user privs drop all prives now!
925 * Not needed on PRIV_SU systems!
932 /* Read server configuration options from the configuration file. */
933 read_server_config(&options, config_file_name);
935 /* Fill in default values for those options not explicitly set. */
936 fill_default_server_options(&options);
938 /* Check that there are no remaining arguments. */
940 fprintf(stderr, "Extra argument %s.\n", av[optind]);
944 debug("sshd version %.100s", SSH_VERSION);
946 /* load private host keys */
947 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
948 for (i = 0; i < options.num_host_key_files; i++)
949 sensitive_data.host_keys[i] = NULL;
950 sensitive_data.server_key = NULL;
951 sensitive_data.ssh1_host_key = NULL;
952 sensitive_data.have_ssh1_key = 0;
953 sensitive_data.have_ssh2_key = 0;
955 for (i = 0; i < options.num_host_key_files; i++) {
956 key = key_load_private(options.host_key_files[i], "", NULL);
957 sensitive_data.host_keys[i] = key;
959 error("Could not load host key: %s",
960 options.host_key_files[i]);
961 sensitive_data.host_keys[i] = NULL;
966 sensitive_data.ssh1_host_key = key;
967 sensitive_data.have_ssh1_key = 1;
971 sensitive_data.have_ssh2_key = 1;
974 debug("private host key: #%d type %d %s", i, key->type,
977 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
978 log("Disabling protocol version 1. Could not load host key");
979 options.protocol &= ~SSH_PROTO_1;
982 /* The GSSAPI key exchange can run without a host key */
983 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
984 log("Disabling protocol version 2. Could not load host key");
985 options.protocol &= ~SSH_PROTO_2;
988 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
989 log("sshd: no hostkeys available -- exiting.");
993 /* Check certain values for sanity. */
994 if (options.protocol & SSH_PROTO_1) {
995 if (options.server_key_bits < 512 ||
996 options.server_key_bits > 32768) {
997 fprintf(stderr, "Bad server key size.\n");
1001 * Check that server and host key lengths differ sufficiently. This
1002 * is necessary to make double encryption work with rsaref. Oh, I
1003 * hate software patents. I dont know if this can go? Niels
1005 if (options.server_key_bits >
1006 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
1007 options.server_key_bits <
1008 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1009 options.server_key_bits =
1010 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
1011 debug("Forcing server key to %d bits to make it differ from host key.",
1012 options.server_key_bits);
1016 /* Configuration looks good, so exit if in test mode. */
1021 ssh_gssapi_clean_env();
1026 * Clear out any supplemental groups we may have inherited. This
1027 * prevents inadvertent creation of files with bad modes (in the
1028 * portable version at least, it's certainly possible for PAM
1029 * to create a file, and we can't control the code in every
1030 * module which might be used).
1032 if (setgroups(0, NULL) < 0)
1033 debug("setgroups() failed: %.200s", strerror(errno));
1034 #endif /* !HAVE_CYGWIN */
1036 /* Initialize the log (it is reinitialized below in case we forked). */
1037 if (debug_flag && !inetd_flag)
1039 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1042 * If not in debugging mode, and not started from inetd, disconnect
1043 * from the controlling terminal, and fork. The original process
1046 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1049 #endif /* TIOCNOTTY */
1050 if (daemon(0, 0) < 0)
1051 fatal("daemon() failed: %.200s", strerror(errno));
1053 /* Disconnect from the controlling tty. */
1055 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1057 (void) ioctl(fd, TIOCNOTTY, NULL);
1060 #endif /* TIOCNOTTY */
1062 /* Reinitialize the log (because of the fork above). */
1063 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1065 /* Initialize the random number generator. */
1068 /* Chdir to the root directory so that the current disk can be
1069 unmounted if desired. */
1072 /* ignore SIGPIPE */
1073 signal(SIGPIPE, SIG_IGN);
1075 /* Start listening for a socket, unless started from inetd. */
1078 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1084 * We intentionally do not close the descriptors 0, 1, and 2
1085 * as our code for setting the descriptors won\'t work if
1086 * ttyfd happens to be one of those.
1088 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1089 if (options.protocol & SSH_PROTO_1)
1090 generate_ephemeral_server_key();
1092 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1093 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1095 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1096 fatal("Too many listen sockets. "
1097 "Enlarge MAX_LISTEN_SOCKS");
1098 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1099 ntop, sizeof(ntop), strport, sizeof(strport),
1100 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1101 error("getnameinfo failed");
1104 /* Create socket for listening. */
1105 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
1106 if (listen_sock < 0) {
1107 /* kernel may not support ipv6 */
1108 verbose("socket: %.100s", strerror(errno));
1111 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1112 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1117 * Set socket options. We try to make the port
1118 * reusable and have it close as fast as possible
1119 * without waiting in unnecessary wait states on
1122 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1125 linger.l_linger = 5;
1126 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
1127 &linger, sizeof(linger));
1129 debug("Bind to port %s on %s.", strport, ntop);
1131 /* Bind the socket to the desired port. */
1132 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1134 error("Bind to port %s on %s failed: %.200s.",
1135 strport, ntop, strerror(errno));
1139 listen_socks[num_listen_socks] = listen_sock;
1142 /* Start listening on the port. */
1143 log("Server listening on %s port %s.", ntop, strport);
1144 if (listen(listen_sock, 5) < 0)
1145 fatal("listen: %.100s", strerror(errno));
1148 freeaddrinfo(options.listen_addrs);
1150 if (!num_listen_socks)
1151 fatal("Cannot bind any address.");
1153 if (options.protocol & SSH_PROTO_1)
1154 generate_ephemeral_server_key();
1157 * Arrange to restart on SIGHUP. The handler needs
1160 signal(SIGHUP, sighup_handler);
1162 signal(SIGTERM, sigterm_handler);
1163 signal(SIGQUIT, sigterm_handler);
1165 /* Arrange SIGCHLD to be caught. */
1166 signal(SIGCHLD, main_sigchld_handler);
1168 /* Write out the pid file after the sigterm handler is setup */
1171 * Record our pid in /var/run/sshd.pid to make it
1172 * easier to kill the correct sshd. We don't want to
1173 * do this before the bind above because the bind will
1174 * fail if there already is a daemon, and this will
1175 * overwrite any old pid in the file.
1177 f = fopen(options.pid_file, "wb");
1179 fprintf(f, "%u\n", (u_int) getpid());
1184 /* setup fd set for listen */
1187 for (i = 0; i < num_listen_socks; i++)
1188 if (listen_socks[i] > maxfd)
1189 maxfd = listen_socks[i];
1190 /* pipes connected to unauthenticated childs */
1191 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1192 for (i = 0; i < options.max_startups; i++)
1193 startup_pipes[i] = -1;
1196 * Stay listening for connections until the system crashes or
1197 * the daemon is killed with a signal.
1200 if (received_sighup)
1204 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1205 fdset = (fd_set *)xmalloc(fdsetsz);
1206 memset(fdset, 0, fdsetsz);
1208 for (i = 0; i < num_listen_socks; i++)
1209 FD_SET(listen_socks[i], fdset);
1210 for (i = 0; i < options.max_startups; i++)
1211 if (startup_pipes[i] != -1)
1212 FD_SET(startup_pipes[i], fdset);
1214 /* Wait in select until there is a connection. */
1215 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1216 if (ret < 0 && errno != EINTR)
1217 error("select: %.100s", strerror(errno));
1218 if (received_sigterm) {
1219 log("Received signal %d; terminating.",
1220 (int) received_sigterm);
1221 close_listen_socks();
1222 unlink(options.pid_file);
1225 if (key_used && key_do_regen) {
1226 generate_ephemeral_server_key();
1233 for (i = 0; i < options.max_startups; i++)
1234 if (startup_pipes[i] != -1 &&
1235 FD_ISSET(startup_pipes[i], fdset)) {
1237 * the read end of the pipe is ready
1238 * if the child has closed the pipe
1239 * after successful authentication
1240 * or if the child has died
1242 close(startup_pipes[i]);
1243 startup_pipes[i] = -1;
1246 for (i = 0; i < num_listen_socks; i++) {
1247 if (!FD_ISSET(listen_socks[i], fdset))
1249 fromlen = sizeof(from);
1250 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1253 if (errno != EINTR && errno != EWOULDBLOCK)
1254 error("accept: %.100s", strerror(errno));
1257 if (fcntl(newsock, F_SETFL, 0) < 0) {
1258 error("newsock del O_NONBLOCK: %s", strerror(errno));
1262 if (drop_connection(startups) == 1) {
1263 debug("drop connection #%d", startups);
1267 if (pipe(startup_p) == -1) {
1272 for (j = 0; j < options.max_startups; j++)
1273 if (startup_pipes[j] == -1) {
1274 startup_pipes[j] = startup_p[0];
1275 if (maxfd < startup_p[0])
1276 maxfd = startup_p[0];
1282 * Got connection. Fork a child to handle it, unless
1283 * we are in debugging mode.
1287 * In debugging mode. Close the listening
1288 * socket, and start processing the
1289 * connection without forking.
1291 debug("Server will not fork when running in debugging mode.");
1292 close_listen_socks();
1300 * Normal production daemon. Fork, and have
1301 * the child process the connection. The
1302 * parent continues listening.
1304 if ((pid = fork()) == 0) {
1306 * Child. Close the listening and max_startup
1307 * sockets. Start using the accepted socket.
1308 * Reinitialize logging (since our pid has
1309 * changed). We break out of the loop to handle
1312 startup_pipe = startup_p[1];
1313 close_startup_pipes();
1314 close_listen_socks();
1317 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1322 /* Parent. Stay in the loop. */
1324 error("fork: %.100s", strerror(errno));
1326 debug("Forked child %d.", pid);
1328 close(startup_p[1]);
1330 /* Mark that the key has been used (it was "given" to the child). */
1331 if ((options.protocol & SSH_PROTO_1) &&
1333 /* Schedule server key regeneration alarm. */
1334 signal(SIGALRM, key_regeneration_alarm);
1335 alarm(options.key_regeneration_time);
1341 /* Close the new socket (the child is now taking care of it). */
1344 /* child process check (or debug mode) */
1345 if (num_listen_socks < 0)
1350 /* This is the child processing a new connection. */
1353 * Create a new session and process group since the 4.4BSD
1354 * setlogin() affects the entire process group. We don't
1355 * want the child to be able to affect the parent.
1358 /* XXX: this breaks Solaris */
1360 error("setsid: %.100s", strerror(errno));
1364 * Disable the key regeneration alarm. We will not regenerate the
1365 * key since we are no longer in a position to give it to anyone. We
1366 * will not restart on SIGHUP since it no longer makes sense.
1369 signal(SIGALRM, SIG_DFL);
1370 signal(SIGHUP, SIG_DFL);
1371 signal(SIGTERM, SIG_DFL);
1372 signal(SIGQUIT, SIG_DFL);
1373 signal(SIGCHLD, SIG_DFL);
1374 signal(SIGINT, SIG_DFL);
1377 * Set socket options for the connection. We want the socket to
1378 * close as fast as possible without waiting for anything. If the
1379 * connection is not a socket, these will do nothing.
1381 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1383 linger.l_linger = 5;
1384 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
1386 /* Set keepalives if requested. */
1387 if (options.keepalives &&
1388 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1390 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1393 * Register our connection. This turns encryption off because we do
1396 packet_set_connection(sock_in, sock_out);
1398 remote_port = get_remote_port();
1399 remote_ip = get_remote_ipaddr();
1402 /* Check whether logins are denied from this host. */
1404 struct request_info req;
1406 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1409 if (!hosts_access(&req)) {
1410 debug("Connection refused by tcp wrapper");
1413 fatal("libwrap refuse returns");
1416 #endif /* LIBWRAP */
1418 /* Log the connection. */
1419 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1422 * We don\'t want to listen forever unless the other side
1423 * successfully authenticates itself. So we set up an alarm which is
1424 * cleared after successful authentication. A limit of zero
1425 * indicates no limit. Note that we don\'t set the alarm in debugging
1426 * mode; it is just annoying to have the server exit just when you
1427 * are about to discover the bug.
1429 signal(SIGALRM, grace_alarm_handler);
1431 alarm(options.login_grace_time);
1433 sshd_exchange_identification(sock_in, sock_out);
1435 * Check that the connection comes from a privileged port.
1436 * Rhosts-Authentication only makes sense from priviledged
1437 * programs. Of course, if the intruder has root access on his local
1438 * machine, he can connect from any port. So do not use these
1439 * authentication methods from machines that you do not trust.
1441 if (options.rhosts_authentication &&
1442 (remote_port >= IPPORT_RESERVED ||
1443 remote_port < IPPORT_RESERVED / 2)) {
1444 debug("Rhosts Authentication disabled, "
1445 "originating port %d not trusted.", remote_port);
1446 options.rhosts_authentication = 0;
1448 #if defined(KRB4) && !defined(KRB5)
1449 if (!packet_connection_is_ipv4() &&
1450 options.kerberos_authentication) {
1451 debug("Kerberos Authentication disabled, only available for IPv4.");
1452 options.kerberos_authentication = 0;
1454 #endif /* KRB4 && !KRB5 */
1456 /* If machine has AFS, set process authentication group. */
1463 packet_set_nonblocking();
1466 if ((authctxt = privsep_preauth()) != NULL)
1469 /* perform the key exchange */
1470 /* authenticate user and start session */
1473 authctxt = do_authentication2();
1476 authctxt = do_authentication();
1479 * If we use privilege separation, the unprivileged child transfers
1480 * the current keystate and exits
1483 mm_send_keystate(pmonitor);
1489 * In privilege separation, we fork another child and prepare
1490 * file descriptor passing.
1493 privsep_postauth(authctxt);
1494 /* the monitor process [priv] will not return */
1496 destroy_sensitive_data();
1499 /* Perform session preparation. */
1500 do_authenticated(authctxt);
1502 /* The connection has been terminated. */
1503 verbose("Closing connection to %.100s", remote_ip);
1507 #endif /* USE_PAM */
1518 * Decrypt session_key_int using our private server key and private host key
1519 * (key with larger modulus first).
1522 ssh1_session_key(BIGNUM *session_key_int)
1526 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1527 /* Server key has bigger modulus. */
1528 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1529 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1530 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1531 get_remote_ipaddr(),
1532 BN_num_bits(sensitive_data.server_key->rsa->n),
1533 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1534 SSH_KEY_BITS_RESERVED);
1536 if (rsa_private_decrypt(session_key_int, session_key_int,
1537 sensitive_data.server_key->rsa) <= 0)
1539 if (rsa_private_decrypt(session_key_int, session_key_int,
1540 sensitive_data.ssh1_host_key->rsa) <= 0)
1543 /* Host key has bigger modulus (or they are equal). */
1544 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1545 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1546 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1547 get_remote_ipaddr(),
1548 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1549 BN_num_bits(sensitive_data.server_key->rsa->n),
1550 SSH_KEY_BITS_RESERVED);
1552 if (rsa_private_decrypt(session_key_int, session_key_int,
1553 sensitive_data.ssh1_host_key->rsa) < 0)
1555 if (rsa_private_decrypt(session_key_int, session_key_int,
1556 sensitive_data.server_key->rsa) < 0)
1569 BIGNUM *session_key_int;
1570 u_char session_key[SSH_SESSION_KEY_LENGTH];
1572 u_int cipher_type, auth_mask, protocol_flags;
1576 * Generate check bytes that the client must send back in the user
1577 * packet in order for it to be accepted; this is used to defy ip
1578 * spoofing attacks. Note that this only works against somebody
1579 * doing IP spoofing from a remote machine; any machine on the local
1580 * network can still see outgoing packets and catch the random
1581 * cookie. This only affects rhosts authentication, and this is one
1582 * of the reasons why it is inherently insecure.
1584 for (i = 0; i < 8; i++) {
1586 rand = arc4random();
1587 cookie[i] = rand & 0xff;
1592 * Send our public key. We include in the packet 64 bits of random
1593 * data that must be matched in the reply in order to prevent IP
1596 packet_start(SSH_SMSG_PUBLIC_KEY);
1597 for (i = 0; i < 8; i++)
1598 packet_put_char(cookie[i]);
1600 /* Store our public server RSA key. */
1601 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1602 packet_put_bignum(sensitive_data.server_key->rsa->e);
1603 packet_put_bignum(sensitive_data.server_key->rsa->n);
1605 /* Store our public host RSA key. */
1606 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1607 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1608 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1610 /* Put protocol flags. */
1611 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1613 /* Declare which ciphers we support. */
1614 packet_put_int(cipher_mask_ssh1(0));
1616 /* Declare supported authentication types. */
1618 if (options.rhosts_authentication)
1619 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1620 if (options.rhosts_rsa_authentication)
1621 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1622 if (options.rsa_authentication)
1623 auth_mask |= 1 << SSH_AUTH_RSA;
1624 #if defined(KRB4) || defined(KRB5)
1625 if (options.kerberos_authentication)
1626 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1628 #if defined(AFS) || defined(KRB5)
1629 if (options.kerberos_tgt_passing)
1630 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1633 if (options.afs_token_passing)
1634 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1636 if (options.challenge_response_authentication == 1)
1637 auth_mask |= 1 << SSH_AUTH_TIS;
1640 if (options.gss_authentication)
1641 auth_mask |= 1 << SSH_AUTH_GSSAPI;
1644 if (options.password_authentication)
1645 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1646 packet_put_int(auth_mask);
1648 /* Send the packet and wait for it to be sent. */
1650 packet_write_wait();
1652 debug("Sent %d bit server key and %d bit host key.",
1653 BN_num_bits(sensitive_data.server_key->rsa->n),
1654 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1656 /* Read clients reply (cipher type and session key). */
1657 packet_read_expect(SSH_CMSG_SESSION_KEY);
1659 /* Get cipher type and check whether we accept this. */
1660 cipher_type = packet_get_char();
1662 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1663 packet_disconnect("Warning: client selects unsupported cipher.");
1665 /* Get check bytes from the packet. These must match those we
1666 sent earlier with the public key packet. */
1667 for (i = 0; i < 8; i++)
1668 if (cookie[i] != packet_get_char())
1669 packet_disconnect("IP Spoofing check bytes do not match.");
1671 debug("Encryption type: %.200s", cipher_name(cipher_type));
1673 /* Get the encrypted integer. */
1674 if ((session_key_int = BN_new()) == NULL)
1675 fatal("do_ssh1_kex: BN_new failed");
1676 packet_get_bignum(session_key_int);
1678 protocol_flags = packet_get_int();
1679 packet_set_protocol_flags(protocol_flags);
1682 /* Decrypt session_key_int using host/server keys */
1683 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1686 * Extract session key from the decrypted integer. The key is in the
1687 * least significant 256 bits of the integer; the first byte of the
1688 * key is in the highest bits.
1691 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1692 len = BN_num_bytes(session_key_int);
1693 if (len < 0 || len > sizeof(session_key)) {
1694 error("do_connection: bad session key len from %s: "
1695 "session_key_int %d > sizeof(session_key) %lu",
1696 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1699 memset(session_key, 0, sizeof(session_key));
1700 BN_bn2bin(session_key_int,
1701 session_key + sizeof(session_key) - len);
1703 compute_session_id(session_id, cookie,
1704 sensitive_data.ssh1_host_key->rsa->n,
1705 sensitive_data.server_key->rsa->n);
1707 * Xor the first 16 bytes of the session key with the
1710 for (i = 0; i < 16; i++)
1711 session_key[i] ^= session_id[i];
1715 int bytes = BN_num_bytes(session_key_int);
1716 u_char *buf = xmalloc(bytes);
1719 log("do_connection: generating a fake encryption key");
1720 BN_bn2bin(session_key_int, buf);
1722 MD5_Update(&md, buf, bytes);
1723 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1724 MD5_Final(session_key, &md);
1726 MD5_Update(&md, session_key, 16);
1727 MD5_Update(&md, buf, bytes);
1728 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1729 MD5_Final(session_key + 16, &md);
1730 memset(buf, 0, bytes);
1732 for (i = 0; i < 16; i++)
1733 session_id[i] = session_key[i] ^ session_key[i + 16];
1738 * Before we destroy the host and server keys, hash them so we can
1739 * send the hash over to the client via a secure channel so that it
1745 unsigned char *data;
1746 unsigned int data_len;
1747 extern unsigned char ssh1_key_digest[]; /* in gss-serv.c */
1750 debug("Calculating MD5 hash of server and host keys...");
1752 /* Write all the keys to a temporary buffer */
1756 buffer_put_bignum(&buf, sensitive_data.server_key->rsa->e);
1757 buffer_put_bignum(&buf, sensitive_data.server_key->rsa->n);
1760 buffer_put_bignum(&buf, sensitive_data.ssh1_host_key->rsa->e);
1761 buffer_put_bignum(&buf, sensitive_data.ssh1_host_key->rsa->n);
1763 /* Get the resulting data */
1764 data = (unsigned char *) buffer_ptr(&buf);
1765 data_len = buffer_len(&buf);
1768 MD5_Init(&md5context);
1769 MD5_Update(&md5context, data, data_len);
1770 MD5_Final(ssh1_key_digest, &md5context);
1778 /* Destroy the private and public keys. No longer. */
1779 destroy_sensitive_data();
1782 mm_ssh1_session_id(session_id);
1784 /* Destroy the decrypted integer. It is no longer needed. */
1785 BN_clear_free(session_key_int);
1787 /* Set the session key. From this on all communications will be encrypted. */
1788 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1790 /* Destroy our copy of the session key. It is no longer needed. */
1791 memset(session_key, 0, sizeof(session_key));
1793 debug("Received session key; encryption turned on.");
1795 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1796 packet_start(SSH_SMSG_SUCCESS);
1798 packet_write_wait();
1802 * SSH2 key exchange: diffie-hellman-group1-sha1
1809 if (options.ciphers != NULL) {
1810 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1811 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1813 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1814 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1815 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1816 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1818 if (options.macs != NULL) {
1819 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1820 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1822 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1828 char *newstr = NULL;
1829 orig = myproposal[PROPOSAL_KEX_ALGS];
1831 /* If we don't have a host key, then all of the algorithms
1832 * currently in myproposal are useless */
1833 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
1836 if (options.gss_keyex)
1837 gss = ssh_gssapi_mechanisms(1,NULL);
1842 int len = strlen(orig) + strlen(gss) +2;
1843 newstr=xmalloc(len);
1844 snprintf(newstr,len,"%s,%s",gss,orig);
1850 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
1851 host key algorithm, but we're not allowed to advertise it, unless
1852 its the only host key algorithm we're supporting */
1853 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
1854 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
1857 myproposal[PROPOSAL_KEX_ALGS]=newstr;
1859 fatal("No supported key exchange algorithms");
1863 /* start key exchange */
1864 kex = kex_setup(myproposal);
1866 kex->client_version_string=client_version_string;
1867 kex->server_version_string=server_version_string;
1868 kex->load_host_key=&get_hostkey_by_type;
1869 kex->host_key_index=&get_hostkey_index;
1873 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1875 session_id2 = kex->session_id;
1876 session_id2_len = kex->session_id_len;
1879 /* send 1st encrypted/maced/compressed message */
1880 packet_start(SSH2_MSG_IGNORE);
1881 packet_put_cstring("markus");
1883 packet_write_wait();