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 1.251 2002/06/25 18:51:04 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"
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)
227 for (i = 0; i < num_listen_socks; i++)
228 close(listen_socks[i]);
229 num_listen_socks = -1;
233 close_startup_pipes(void)
238 for (i = 0; i < options.max_startups; i++)
239 if (startup_pipes[i] != -1)
240 close(startup_pipes[i]);
244 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
245 * the effect is to reread the configuration file (and to regenerate
249 sighup_handler(int sig)
251 int save_errno = errno;
254 signal(SIGHUP, sighup_handler);
259 * Called from the main program after receiving SIGHUP.
260 * Restarts the server.
265 log("Received SIGHUP; restarting.");
266 close_listen_socks();
267 close_startup_pipes();
268 execv(saved_argv[0], saved_argv);
269 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
275 * Generic signal handler for terminating signals in the master daemon.
278 sigterm_handler(int sig)
280 received_sigterm = sig;
284 * SIGCHLD handler. This is called whenever a child dies. This will then
285 * reap any zombies left by exited children.
288 main_sigchld_handler(int sig)
290 int save_errno = errno;
294 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
295 (pid < 0 && errno == EINTR))
298 signal(SIGCHLD, main_sigchld_handler);
303 * Signal handler for the alarm after the login grace period has expired.
306 grace_alarm_handler(int sig)
308 /* XXX no idea how fix this signal handler */
310 /* Close the connection. */
313 /* Log error and exit. */
314 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
318 * Signal handler for the key regeneration alarm. Note that this
319 * alarm only occurs in the daemon waiting for connections, and it does not
320 * do anything with the private key or random state before forking.
321 * Thus there should be no concurrency control/asynchronous execution
325 generate_ephemeral_server_key(void)
330 verbose("Generating %s%d bit RSA key.",
331 sensitive_data.server_key ? "new " : "", options.server_key_bits);
332 if (sensitive_data.server_key != NULL)
333 key_free(sensitive_data.server_key);
334 sensitive_data.server_key = key_generate(KEY_RSA1,
335 options.server_key_bits);
336 verbose("RSA key generation complete.");
338 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
341 sensitive_data.ssh1_cookie[i] = rand & 0xff;
348 key_regeneration_alarm(int sig)
350 int save_errno = errno;
352 signal(SIGALRM, SIG_DFL);
358 sshd_exchange_identification(int sock_in, int sock_out)
361 int remote_major, remote_minor;
364 char buf[256]; /* Must not be larger than remote_version. */
365 char remote_version[256]; /* Must be at least as big as buf. */
367 if ((options.protocol & SSH_PROTO_1) &&
368 (options.protocol & SSH_PROTO_2)) {
369 major = PROTOCOL_MAJOR_1;
371 } else if (options.protocol & SSH_PROTO_2) {
372 major = PROTOCOL_MAJOR_2;
373 minor = PROTOCOL_MINOR_2;
375 major = PROTOCOL_MAJOR_1;
376 minor = PROTOCOL_MINOR_1;
378 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
379 server_version_string = xstrdup(buf);
381 if (client_version_string == NULL) {
382 /* Send our protocol version identification. */
383 if (atomicio(write, sock_out, server_version_string,
384 strlen(server_version_string))
385 != strlen(server_version_string)) {
386 log("Could not write ident string to %s", get_remote_ipaddr());
390 /* Read other sides version identification. */
391 memset(buf, 0, sizeof(buf));
392 for (i = 0; i < sizeof(buf) - 1; i++) {
393 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
394 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);
487 /* Destroy the host and server keys. They will no longer be needed. */
489 destroy_sensitive_data(void)
493 if (sensitive_data.server_key) {
494 key_free(sensitive_data.server_key);
495 sensitive_data.server_key = NULL;
497 for (i = 0; i < options.num_host_key_files; i++) {
498 if (sensitive_data.host_keys[i]) {
499 key_free(sensitive_data.host_keys[i]);
500 sensitive_data.host_keys[i] = NULL;
503 sensitive_data.ssh1_host_key = NULL;
504 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
507 /* Demote private to public keys for network child */
509 demote_sensitive_data(void)
514 if (sensitive_data.server_key) {
515 tmp = key_demote(sensitive_data.server_key);
516 key_free(sensitive_data.server_key);
517 sensitive_data.server_key = tmp;
520 for (i = 0; i < options.num_host_key_files; i++) {
521 if (sensitive_data.host_keys[i]) {
522 tmp = key_demote(sensitive_data.host_keys[i]);
523 key_free(sensitive_data.host_keys[i]);
524 sensitive_data.host_keys[i] = tmp;
525 if (tmp->type == KEY_RSA1)
526 sensitive_data.ssh1_host_key = tmp;
530 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
534 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,
568 /* XXX not ready, to heavy after chroot */
569 do_setusercontext(pw);
571 gidset[0] = pw->pw_gid;
572 if (setgid(pw->pw_gid) < 0)
573 fatal("setgid failed for %u", pw->pw_gid );
574 if (setgroups(1, gidset) < 0)
575 fatal("setgroups: %.100s", strerror(errno));
576 permanently_set_uid(pw);
581 privsep_preauth(void)
583 Authctxt *authctxt = NULL;
587 /* Set up unprivileged child process to deal with network data */
588 pmonitor = monitor_init();
589 /* Store a pointer to the kex for later rekeying */
590 pmonitor->m_pkex = &xxx_kex;
594 fatal("fork of unprivileged child failed");
595 } else if (pid != 0) {
596 debug2("Network child is on pid %ld", (long)pid);
598 close(pmonitor->m_recvfd);
599 authctxt = monitor_child_preauth(pmonitor);
600 close(pmonitor->m_sendfd);
603 monitor_sync(pmonitor);
605 /* Wait for the child's exit status */
606 while (waitpid(pid, &status, 0) < 0)
613 close(pmonitor->m_sendfd);
615 /* Demote the child */
616 if (getuid() == 0 || geteuid() == 0)
617 privsep_preauth_child();
618 setproctitle("%s", "[net]");
624 privsep_postauth(Authctxt *authctxt)
626 extern Authctxt *x_authctxt;
628 /* XXX - Remote port forwarding */
629 x_authctxt = authctxt;
631 #ifdef BROKEN_FD_PASSING
634 if (authctxt->pw->pw_uid == 0 || options.use_login) {
636 /* File descriptor passing is broken or root login */
637 monitor_apply_keystate(pmonitor);
642 /* Authentication complete */
644 if (startup_pipe != -1) {
649 /* New socket pair */
650 monitor_reinit(pmonitor);
652 pmonitor->m_pid = fork();
653 if (pmonitor->m_pid == -1)
654 fatal("fork of unprivileged child failed");
655 else if (pmonitor->m_pid != 0) {
656 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
657 close(pmonitor->m_recvfd);
658 monitor_child_postauth(pmonitor);
664 close(pmonitor->m_sendfd);
666 /* Demote the private keys to public keys. */
667 demote_sensitive_data();
669 /* Drop privileges */
670 do_setusercontext(authctxt->pw);
672 /* It is safe now to apply the key state */
673 monitor_apply_keystate(pmonitor);
677 list_hostkey_types(void)
684 for (i = 0; i < options.num_host_key_files; i++) {
685 Key *key = sensitive_data.host_keys[i];
691 if (buffer_len(&b) > 0)
692 buffer_append(&b, ",", 1);
693 p = key_ssh_name(key);
694 buffer_append(&b, p, strlen(p));
698 buffer_append(&b, "\0", 1);
699 p = xstrdup(buffer_ptr(&b));
701 debug("list_hostkey_types: %s", p);
706 get_hostkey_by_type(int type)
710 for (i = 0; i < options.num_host_key_files; i++) {
711 Key *key = sensitive_data.host_keys[i];
712 if (key != NULL && key->type == type)
719 get_hostkey_by_index(int ind)
721 if (ind < 0 || ind >= options.num_host_key_files)
723 return (sensitive_data.host_keys[ind]);
727 get_hostkey_index(Key *key)
731 for (i = 0; i < options.num_host_key_files; i++) {
732 if (key == sensitive_data.host_keys[i])
739 * returns 1 if connection should be dropped, 0 otherwise.
740 * dropping starts at connection #max_startups_begin with a probability
741 * of (max_startups_rate/100). the probability increases linearly until
742 * all connections are dropped for startups > max_startups
745 drop_connection(int startups)
749 if (startups < options.max_startups_begin)
751 if (startups >= options.max_startups)
753 if (options.max_startups_rate == 100)
756 p = 100 - options.max_startups_rate;
757 p *= startups - options.max_startups_begin;
758 p /= (double) (options.max_startups - options.max_startups_begin);
759 p += options.max_startups_rate;
761 r = arc4random() / (double) UINT_MAX;
763 debug("drop_connection: p %g, r %g", p, r);
764 return (r < p) ? 1 : 0;
770 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
771 fprintf(stderr, "Usage: %s [options]\n", __progname);
772 fprintf(stderr, "Options:\n");
773 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
774 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
775 fprintf(stderr, " -i Started from inetd\n");
776 fprintf(stderr, " -D Do not fork into daemon mode\n");
777 fprintf(stderr, " -t Only test configuration file and keys\n");
778 fprintf(stderr, " -q Quiet (no logging)\n");
779 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
780 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
781 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
782 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
783 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
784 _PATH_HOST_KEY_FILE);
785 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
786 fprintf(stderr, " -4 Use IPv4 only\n");
787 fprintf(stderr, " -6 Use IPv6 only\n");
788 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
793 * Main program for the daemon.
796 main(int ac, char **av)
800 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
804 struct sockaddr_storage from;
805 const char *remote_ip;
808 struct linger linger;
810 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
811 int listen_sock, maxfd;
816 int ret, key_used = 0;
818 #ifdef HAVE_SECUREWARE
819 (void)set_auth_parameters(ac, av);
821 __progname = get_progname(av[0]);
828 /* Initialize configuration options to their default values. */
829 initialize_server_options(&options);
831 /* Parse command-line arguments. */
832 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
841 config_file_name = optarg;
844 if (0 == debug_flag) {
846 options.log_level = SYSLOG_LEVEL_DEBUG1;
847 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
850 fprintf(stderr, "Too high debugging level.\n");
867 options.log_level = SYSLOG_LEVEL_QUIET;
870 options.server_key_bits = atoi(optarg);
873 options.ports_from_cmdline = 1;
874 if (options.num_ports >= MAX_PORTS) {
875 fprintf(stderr, "too many ports.\n");
878 options.ports[options.num_ports++] = a2port(optarg);
879 if (options.ports[options.num_ports-1] == 0) {
880 fprintf(stderr, "Bad port number.\n");
885 if ((options.login_grace_time = convtime(optarg)) == -1) {
886 fprintf(stderr, "Invalid login grace time.\n");
891 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
892 fprintf(stderr, "Invalid key regeneration interval.\n");
897 if (options.num_host_key_files >= MAX_HOSTKEYS) {
898 fprintf(stderr, "too many host keys.\n");
901 options.host_key_files[options.num_host_key_files++] = optarg;
904 client_version_string = optarg;
905 /* only makes sense with inetd_flag, i.e. no listen() */
912 utmp_len = atoi(optarg);
915 if (process_server_config_line(&options, optarg,
916 "command-line", 0) != 0)
925 SSLeay_add_all_algorithms();
926 channel_set_af(IPv4or6);
929 * Force logging to stderr until we have loaded the private host
930 * key (unless started from inetd)
933 options.log_level == SYSLOG_LEVEL_NOT_SET ?
934 SYSLOG_LEVEL_INFO : options.log_level,
935 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
936 SYSLOG_FACILITY_AUTH : options.log_facility,
940 /* Cray can define user privs drop all prives now!
941 * Not needed on PRIV_SU systems!
948 /* Read server configuration options from the configuration file. */
949 read_server_config(&options, config_file_name);
951 /* Fill in default values for those options not explicitly set. */
952 fill_default_server_options(&options);
954 /* Check that there are no remaining arguments. */
956 fprintf(stderr, "Extra argument %s.\n", av[optind]);
960 debug("sshd version %.100s", SSH_VERSION);
962 /* load private host keys */
963 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
964 for (i = 0; i < options.num_host_key_files; i++)
965 sensitive_data.host_keys[i] = NULL;
966 sensitive_data.server_key = NULL;
967 sensitive_data.ssh1_host_key = NULL;
968 sensitive_data.have_ssh1_key = 0;
969 sensitive_data.have_ssh2_key = 0;
971 for (i = 0; i < options.num_host_key_files; i++) {
972 key = key_load_private(options.host_key_files[i], "", NULL);
973 sensitive_data.host_keys[i] = key;
975 error("Could not load host key: %s",
976 options.host_key_files[i]);
977 sensitive_data.host_keys[i] = NULL;
982 sensitive_data.ssh1_host_key = key;
983 sensitive_data.have_ssh1_key = 1;
987 sensitive_data.have_ssh2_key = 1;
990 debug("private host key: #%d type %d %s", i, key->type,
993 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
994 log("Disabling protocol version 1. Could not load host key");
995 options.protocol &= ~SSH_PROTO_1;
998 /* The GSSAPI key exchange can run without a host key */
999 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1000 log("Disabling protocol version 2. Could not load host key");
1001 options.protocol &= ~SSH_PROTO_2;
1004 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1005 log("sshd: no hostkeys available -- exiting.");
1009 /* Check certain values for sanity. */
1010 if (options.protocol & SSH_PROTO_1) {
1011 if (options.server_key_bits < 512 ||
1012 options.server_key_bits > 32768) {
1013 fprintf(stderr, "Bad server key size.\n");
1017 * Check that server and host key lengths differ sufficiently. This
1018 * is necessary to make double encryption work with rsaref. Oh, I
1019 * hate software patents. I dont know if this can go? Niels
1021 if (options.server_key_bits >
1022 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1023 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1024 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1025 SSH_KEY_BITS_RESERVED) {
1026 options.server_key_bits =
1027 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1028 SSH_KEY_BITS_RESERVED;
1029 debug("Forcing server key to %d bits to make it differ from host key.",
1030 options.server_key_bits);
1038 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1039 fatal("Privilege separation user %s does not exist",
1041 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1042 (S_ISDIR(st.st_mode) == 0))
1043 fatal("Missing privilege separation directory: %s",
1044 _PATH_PRIVSEP_CHROOT_DIR);
1045 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1046 fatal("Bad owner or mode for %s",
1047 _PATH_PRIVSEP_CHROOT_DIR);
1050 /* Configuration looks good, so exit if in test mode. */
1055 * Clear out any supplemental groups we may have inherited. This
1056 * prevents inadvertent creation of files with bad modes (in the
1057 * portable version at least, it's certainly possible for PAM
1058 * to create a file, and we can't control the code in every
1059 * module which might be used).
1061 if (setgroups(0, NULL) < 0)
1062 debug("setgroups() failed: %.200s", strerror(errno));
1064 /* Initialize the log (it is reinitialized below in case we forked). */
1065 if (debug_flag && !inetd_flag)
1067 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1070 * If not in debugging mode, and not started from inetd, disconnect
1071 * from the controlling terminal, and fork. The original process
1074 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1077 #endif /* TIOCNOTTY */
1078 if (daemon(0, 0) < 0)
1079 fatal("daemon() failed: %.200s", strerror(errno));
1081 /* Disconnect from the controlling tty. */
1083 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1085 (void) ioctl(fd, TIOCNOTTY, NULL);
1088 #endif /* TIOCNOTTY */
1090 /* Reinitialize the log (because of the fork above). */
1091 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1093 /* Initialize the random number generator. */
1096 /* Chdir to the root directory so that the current disk can be
1097 unmounted if desired. */
1100 /* ignore SIGPIPE */
1101 signal(SIGPIPE, SIG_IGN);
1103 /* Start listening for a socket, unless started from inetd. */
1106 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1112 * We intentionally do not close the descriptors 0, 1, and 2
1113 * as our code for setting the descriptors won\'t work if
1114 * ttyfd happens to be one of those.
1116 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1117 if (options.protocol & SSH_PROTO_1)
1118 generate_ephemeral_server_key();
1120 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1121 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1123 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1124 fatal("Too many listen sockets. "
1125 "Enlarge MAX_LISTEN_SOCKS");
1126 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1127 ntop, sizeof(ntop), strport, sizeof(strport),
1128 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1129 error("getnameinfo failed");
1132 /* Create socket for listening. */
1133 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
1134 if (listen_sock < 0) {
1135 /* kernel may not support ipv6 */
1136 verbose("socket: %.100s", strerror(errno));
1139 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1140 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1145 * Set socket options. We try to make the port
1146 * reusable and have it close as fast as possible
1147 * without waiting in unnecessary wait states on
1150 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1153 linger.l_linger = 5;
1154 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
1155 &linger, sizeof(linger));
1157 debug("Bind to port %s on %s.", strport, ntop);
1159 /* Bind the socket to the desired port. */
1160 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1162 error("Bind to port %s on %s failed: %.200s.",
1163 strport, ntop, strerror(errno));
1167 listen_socks[num_listen_socks] = listen_sock;
1170 /* Start listening on the port. */
1171 log("Server listening on %s port %s.", ntop, strport);
1172 if (listen(listen_sock, 5) < 0)
1173 fatal("listen: %.100s", strerror(errno));
1176 freeaddrinfo(options.listen_addrs);
1178 if (!num_listen_socks)
1179 fatal("Cannot bind any address.");
1181 if (options.protocol & SSH_PROTO_1)
1182 generate_ephemeral_server_key();
1185 * Arrange to restart on SIGHUP. The handler needs
1188 signal(SIGHUP, sighup_handler);
1190 signal(SIGTERM, sigterm_handler);
1191 signal(SIGQUIT, sigterm_handler);
1193 /* Arrange SIGCHLD to be caught. */
1194 signal(SIGCHLD, main_sigchld_handler);
1196 /* Write out the pid file after the sigterm handler is setup */
1199 * Record our pid in /var/run/sshd.pid to make it
1200 * easier to kill the correct sshd. We don't want to
1201 * do this before the bind above because the bind will
1202 * fail if there already is a daemon, and this will
1203 * overwrite any old pid in the file.
1205 f = fopen(options.pid_file, "wb");
1207 fprintf(f, "%ld\n", (long) getpid());
1212 /* setup fd set for listen */
1215 for (i = 0; i < num_listen_socks; i++)
1216 if (listen_socks[i] > maxfd)
1217 maxfd = listen_socks[i];
1218 /* pipes connected to unauthenticated childs */
1219 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1220 for (i = 0; i < options.max_startups; i++)
1221 startup_pipes[i] = -1;
1224 * Stay listening for connections until the system crashes or
1225 * the daemon is killed with a signal.
1228 if (received_sighup)
1232 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1233 fdset = (fd_set *)xmalloc(fdsetsz);
1234 memset(fdset, 0, fdsetsz);
1236 for (i = 0; i < num_listen_socks; i++)
1237 FD_SET(listen_socks[i], fdset);
1238 for (i = 0; i < options.max_startups; i++)
1239 if (startup_pipes[i] != -1)
1240 FD_SET(startup_pipes[i], fdset);
1242 /* Wait in select until there is a connection. */
1243 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1244 if (ret < 0 && errno != EINTR)
1245 error("select: %.100s", strerror(errno));
1246 if (received_sigterm) {
1247 log("Received signal %d; terminating.",
1248 (int) received_sigterm);
1249 close_listen_socks();
1250 unlink(options.pid_file);
1253 if (key_used && key_do_regen) {
1254 generate_ephemeral_server_key();
1261 for (i = 0; i < options.max_startups; i++)
1262 if (startup_pipes[i] != -1 &&
1263 FD_ISSET(startup_pipes[i], fdset)) {
1265 * the read end of the pipe is ready
1266 * if the child has closed the pipe
1267 * after successful authentication
1268 * or if the child has died
1270 close(startup_pipes[i]);
1271 startup_pipes[i] = -1;
1274 for (i = 0; i < num_listen_socks; i++) {
1275 if (!FD_ISSET(listen_socks[i], fdset))
1277 fromlen = sizeof(from);
1278 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1281 if (errno != EINTR && errno != EWOULDBLOCK)
1282 error("accept: %.100s", strerror(errno));
1285 if (fcntl(newsock, F_SETFL, 0) < 0) {
1286 error("newsock del O_NONBLOCK: %s", strerror(errno));
1290 if (drop_connection(startups) == 1) {
1291 debug("drop connection #%d", startups);
1295 if (pipe(startup_p) == -1) {
1300 for (j = 0; j < options.max_startups; j++)
1301 if (startup_pipes[j] == -1) {
1302 startup_pipes[j] = startup_p[0];
1303 if (maxfd < startup_p[0])
1304 maxfd = startup_p[0];
1310 * Got connection. Fork a child to handle it, unless
1311 * we are in debugging mode.
1315 * In debugging mode. Close the listening
1316 * socket, and start processing the
1317 * connection without forking.
1319 debug("Server will not fork when running in debugging mode.");
1320 close_listen_socks();
1328 * Normal production daemon. Fork, and have
1329 * the child process the connection. The
1330 * parent continues listening.
1332 if ((pid = fork()) == 0) {
1334 * Child. Close the listening and max_startup
1335 * sockets. Start using the accepted socket.
1336 * Reinitialize logging (since our pid has
1337 * changed). We break out of the loop to handle
1340 startup_pipe = startup_p[1];
1341 close_startup_pipes();
1342 close_listen_socks();
1345 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1350 /* Parent. Stay in the loop. */
1352 error("fork: %.100s", strerror(errno));
1354 debug("Forked child %ld.", (long)pid);
1356 close(startup_p[1]);
1358 /* Mark that the key has been used (it was "given" to the child). */
1359 if ((options.protocol & SSH_PROTO_1) &&
1361 /* Schedule server key regeneration alarm. */
1362 signal(SIGALRM, key_regeneration_alarm);
1363 alarm(options.key_regeneration_time);
1369 /* Close the new socket (the child is now taking care of it). */
1372 /* child process check (or debug mode) */
1373 if (num_listen_socks < 0)
1378 /* This is the child processing a new connection. */
1381 * Create a new session and process group since the 4.4BSD
1382 * setlogin() affects the entire process group. We don't
1383 * want the child to be able to affect the parent.
1386 /* XXX: this breaks Solaris */
1387 if (!debug_flag && !inetd_flag && setsid() < 0)
1388 error("setsid: %.100s", strerror(errno));
1392 * Disable the key regeneration alarm. We will not regenerate the
1393 * key since we are no longer in a position to give it to anyone. We
1394 * will not restart on SIGHUP since it no longer makes sense.
1397 signal(SIGALRM, SIG_DFL);
1398 signal(SIGHUP, SIG_DFL);
1399 signal(SIGTERM, SIG_DFL);
1400 signal(SIGQUIT, SIG_DFL);
1401 signal(SIGCHLD, SIG_DFL);
1402 signal(SIGINT, SIG_DFL);
1405 * Set socket options for the connection. We want the socket to
1406 * close as fast as possible without waiting for anything. If the
1407 * connection is not a socket, these will do nothing.
1409 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1411 linger.l_linger = 5;
1412 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
1414 /* Set keepalives if requested. */
1415 if (options.keepalives &&
1416 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1418 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1421 * Register our connection. This turns encryption off because we do
1424 packet_set_connection(sock_in, sock_out);
1426 remote_port = get_remote_port();
1427 remote_ip = get_remote_ipaddr();
1430 /* Check whether logins are denied from this host. */
1432 struct request_info req;
1434 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1437 if (!hosts_access(&req)) {
1438 debug("Connection refused by tcp wrapper");
1441 fatal("libwrap refuse returns");
1444 #endif /* LIBWRAP */
1446 /* Log the connection. */
1447 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1450 * We don\'t want to listen forever unless the other side
1451 * successfully authenticates itself. So we set up an alarm which is
1452 * cleared after successful authentication. A limit of zero
1453 * indicates no limit. Note that we don\'t set the alarm in debugging
1454 * mode; it is just annoying to have the server exit just when you
1455 * are about to discover the bug.
1457 signal(SIGALRM, grace_alarm_handler);
1459 alarm(options.login_grace_time);
1461 sshd_exchange_identification(sock_in, sock_out);
1463 * Check that the connection comes from a privileged port.
1464 * Rhosts-Authentication only makes sense from privileged
1465 * programs. Of course, if the intruder has root access on his local
1466 * machine, he can connect from any port. So do not use these
1467 * authentication methods from machines that you do not trust.
1469 if (options.rhosts_authentication &&
1470 (remote_port >= IPPORT_RESERVED ||
1471 remote_port < IPPORT_RESERVED / 2)) {
1472 debug("Rhosts Authentication disabled, "
1473 "originating port %d not trusted.", remote_port);
1474 options.rhosts_authentication = 0;
1476 #if defined(KRB4) && !defined(KRB5)
1477 if (!packet_connection_is_ipv4() &&
1478 options.kerberos_authentication) {
1479 debug("Kerberos Authentication disabled, only available for IPv4.");
1480 options.kerberos_authentication = 0;
1482 #endif /* KRB4 && !KRB5 */
1484 /* If machine has AFS, set process authentication group. */
1491 packet_set_nonblocking();
1494 if ((authctxt = privsep_preauth()) != NULL)
1497 /* perform the key exchange */
1498 /* authenticate user and start session */
1501 authctxt = do_authentication2();
1504 authctxt = do_authentication();
1507 * If we use privilege separation, the unprivileged child transfers
1508 * the current keystate and exits
1511 mm_send_keystate(pmonitor);
1517 * In privilege separation, we fork another child and prepare
1518 * file descriptor passing.
1521 privsep_postauth(authctxt);
1522 /* the monitor process [priv] will not return */
1524 destroy_sensitive_data();
1527 /* Perform session preparation. */
1528 do_authenticated(authctxt);
1530 /* The connection has been terminated. */
1531 verbose("Closing connection to %.100s", remote_ip);
1535 #endif /* USE_PAM */
1546 * Decrypt session_key_int using our private server key and private host key
1547 * (key with larger modulus first).
1550 ssh1_session_key(BIGNUM *session_key_int)
1554 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1555 /* Server key has bigger modulus. */
1556 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1557 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1558 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1559 get_remote_ipaddr(),
1560 BN_num_bits(sensitive_data.server_key->rsa->n),
1561 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1562 SSH_KEY_BITS_RESERVED);
1564 if (rsa_private_decrypt(session_key_int, session_key_int,
1565 sensitive_data.server_key->rsa) <= 0)
1567 if (rsa_private_decrypt(session_key_int, session_key_int,
1568 sensitive_data.ssh1_host_key->rsa) <= 0)
1571 /* Host key has bigger modulus (or they are equal). */
1572 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1573 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1574 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1575 get_remote_ipaddr(),
1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1577 BN_num_bits(sensitive_data.server_key->rsa->n),
1578 SSH_KEY_BITS_RESERVED);
1580 if (rsa_private_decrypt(session_key_int, session_key_int,
1581 sensitive_data.ssh1_host_key->rsa) < 0)
1583 if (rsa_private_decrypt(session_key_int, session_key_int,
1584 sensitive_data.server_key->rsa) < 0)
1597 BIGNUM *session_key_int;
1598 u_char session_key[SSH_SESSION_KEY_LENGTH];
1600 u_int cipher_type, auth_mask, protocol_flags;
1604 * Generate check bytes that the client must send back in the user
1605 * packet in order for it to be accepted; this is used to defy ip
1606 * spoofing attacks. Note that this only works against somebody
1607 * doing IP spoofing from a remote machine; any machine on the local
1608 * network can still see outgoing packets and catch the random
1609 * cookie. This only affects rhosts authentication, and this is one
1610 * of the reasons why it is inherently insecure.
1612 for (i = 0; i < 8; i++) {
1614 rand = arc4random();
1615 cookie[i] = rand & 0xff;
1620 * Send our public key. We include in the packet 64 bits of random
1621 * data that must be matched in the reply in order to prevent IP
1624 packet_start(SSH_SMSG_PUBLIC_KEY);
1625 for (i = 0; i < 8; i++)
1626 packet_put_char(cookie[i]);
1628 /* Store our public server RSA key. */
1629 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1630 packet_put_bignum(sensitive_data.server_key->rsa->e);
1631 packet_put_bignum(sensitive_data.server_key->rsa->n);
1633 /* Store our public host RSA key. */
1634 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1635 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1636 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1638 /* Put protocol flags. */
1639 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1641 /* Declare which ciphers we support. */
1642 packet_put_int(cipher_mask_ssh1(0));
1644 /* Declare supported authentication types. */
1646 if (options.rhosts_authentication)
1647 auth_mask |= 1 << SSH_AUTH_RHOSTS;
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 defined(KRB4) || defined(KRB5)
1653 if (options.kerberos_authentication)
1654 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1656 #if defined(AFS) || defined(KRB5)
1657 if (options.kerberos_tgt_passing)
1658 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1661 if (options.afs_token_passing)
1662 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1664 if (options.challenge_response_authentication == 1)
1665 auth_mask |= 1 << SSH_AUTH_TIS;
1666 if (options.password_authentication)
1667 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1668 packet_put_int(auth_mask);
1670 /* Send the packet and wait for it to be sent. */
1672 packet_write_wait();
1674 debug("Sent %d bit server key and %d bit host key.",
1675 BN_num_bits(sensitive_data.server_key->rsa->n),
1676 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1678 /* Read clients reply (cipher type and session key). */
1679 packet_read_expect(SSH_CMSG_SESSION_KEY);
1681 /* Get cipher type and check whether we accept this. */
1682 cipher_type = packet_get_char();
1684 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1685 packet_disconnect("Warning: client selects unsupported cipher.");
1687 /* Get check bytes from the packet. These must match those we
1688 sent earlier with the public key packet. */
1689 for (i = 0; i < 8; i++)
1690 if (cookie[i] != packet_get_char())
1691 packet_disconnect("IP Spoofing check bytes do not match.");
1693 debug("Encryption type: %.200s", cipher_name(cipher_type));
1695 /* Get the encrypted integer. */
1696 if ((session_key_int = BN_new()) == NULL)
1697 fatal("do_ssh1_kex: BN_new failed");
1698 packet_get_bignum(session_key_int);
1700 protocol_flags = packet_get_int();
1701 packet_set_protocol_flags(protocol_flags);
1704 /* Decrypt session_key_int using host/server keys */
1705 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1708 * Extract session key from the decrypted integer. The key is in the
1709 * least significant 256 bits of the integer; the first byte of the
1710 * key is in the highest bits.
1713 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1714 len = BN_num_bytes(session_key_int);
1715 if (len < 0 || len > sizeof(session_key)) {
1716 error("do_connection: bad session key len from %s: "
1717 "session_key_int %d > sizeof(session_key) %lu",
1718 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1721 memset(session_key, 0, sizeof(session_key));
1722 BN_bn2bin(session_key_int,
1723 session_key + sizeof(session_key) - len);
1725 compute_session_id(session_id, cookie,
1726 sensitive_data.ssh1_host_key->rsa->n,
1727 sensitive_data.server_key->rsa->n);
1729 * Xor the first 16 bytes of the session key with the
1732 for (i = 0; i < 16; i++)
1733 session_key[i] ^= session_id[i];
1737 int bytes = BN_num_bytes(session_key_int);
1738 u_char *buf = xmalloc(bytes);
1741 log("do_connection: generating a fake encryption key");
1742 BN_bn2bin(session_key_int, buf);
1744 MD5_Update(&md, buf, bytes);
1745 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1746 MD5_Final(session_key, &md);
1748 MD5_Update(&md, session_key, 16);
1749 MD5_Update(&md, buf, bytes);
1750 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1751 MD5_Final(session_key + 16, &md);
1752 memset(buf, 0, bytes);
1754 for (i = 0; i < 16; i++)
1755 session_id[i] = session_key[i] ^ session_key[i + 16];
1757 /* Destroy the private and public keys. No longer. */
1758 destroy_sensitive_data();
1761 mm_ssh1_session_id(session_id);
1763 /* Destroy the decrypted integer. It is no longer needed. */
1764 BN_clear_free(session_key_int);
1766 /* Set the session key. From this on all communications will be encrypted. */
1767 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1769 /* Destroy our copy of the session key. It is no longer needed. */
1770 memset(session_key, 0, sizeof(session_key));
1772 debug("Received session key; encryption turned on.");
1774 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1775 packet_start(SSH_SMSG_SUCCESS);
1777 packet_write_wait();
1781 * SSH2 key exchange: diffie-hellman-group1-sha1
1788 if (options.ciphers != NULL) {
1789 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1790 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1792 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1793 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1794 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1795 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1797 if (options.macs != NULL) {
1798 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1799 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1801 if (!options.compression) {
1802 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1803 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1805 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1811 char *newstr = NULL;
1812 orig = myproposal[PROPOSAL_KEX_ALGS];
1814 /* If we don't have a host key, then all of the algorithms
1815 * currently in myproposal are useless */
1816 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
1819 if (options.gss_keyex)
1820 gss = ssh_gssapi_mechanisms(1,NULL);
1825 int len = strlen(orig) + strlen(gss) +2;
1826 newstr=xmalloc(len);
1827 snprintf(newstr,len,"%s,%s",gss,orig);
1833 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
1834 host key algorithm, but we're not allowed to advertise it, unless
1835 its the only host key algorithm we're supporting */
1836 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
1837 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
1840 myproposal[PROPOSAL_KEX_ALGS]=newstr;
1842 fatal("No supported key exchange algorithms");
1846 /* start key exchange */
1847 kex = kex_setup(myproposal);
1849 kex->client_version_string=client_version_string;
1850 kex->server_version_string=server_version_string;
1851 kex->load_host_key=&get_hostkey_by_type;
1852 kex->host_key_index=&get_hostkey_index;
1856 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1858 session_id2 = kex->session_id;
1859 session_id2_len = kex->session_id_len;
1862 /* send 1st encrypted/maced/compressed message */
1863 packet_start(SSH2_MSG_IGNORE);
1864 packet_put_cstring("markus");
1866 packet_write_wait();