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 1.250 2002/06/23 10:29:52 deraadt 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"
91 int allow_severity = LOG_INFO;
92 int deny_severity = LOG_WARNING;
99 #ifdef HAVE___PROGNAME
100 extern char *__progname;
105 /* Server configuration options. */
106 ServerOptions options;
108 /* Name of the server configuration file. */
109 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
112 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
113 * Default value is AF_UNSPEC means both IPv4 and IPv6.
116 int IPv4or6 = AF_INET;
118 int IPv4or6 = AF_UNSPEC;
122 * Debug mode flag. This can be set on the command line. If debug
123 * mode is enabled, extra debugging output will be sent to the system
124 * log, the daemon will not go to background, and will exit after processing
125 * the first connection.
129 /* Flag indicating that the daemon should only test the configuration and keys. */
132 /* Flag indicating that the daemon is being started from inetd. */
135 /* Flag indicating that sshd should not detach and become a daemon. */
136 int no_daemon_flag = 0;
138 /* debug goes to stderr unless inetd_flag is set */
141 /* Saved arguments to main(). */
146 * The sockets that the server is listening; this is used in the SIGHUP
149 #define MAX_LISTEN_SOCKS 16
150 int listen_socks[MAX_LISTEN_SOCKS];
151 int num_listen_socks = 0;
154 * the client's version string, passed by sshd2 in compat mode. if != NULL,
155 * sshd will skip the version-number exchange
157 char *client_version_string = NULL;
158 char *server_version_string = NULL;
160 /* for rekeying XXX fixme */
164 * Any really sensitive data in the application is contained in this
165 * structure. The idea is that this structure could be locked into memory so
166 * that the pages do not get written into swap. However, there are some
167 * problems. The private key contains BIGNUMs, and we do not (in principle)
168 * have access to the internals of them, and locking just the structure is
169 * not very useful. Currently, memory locking is not implemented.
172 Key *server_key; /* ephemeral server key */
173 Key *ssh1_host_key; /* ssh1 host key */
174 Key **host_keys; /* all private host keys */
177 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
181 * Flag indicating whether the RSA server key needs to be regenerated.
182 * Is set in the SIGALRM handler and cleared when the key is regenerated.
184 static volatile sig_atomic_t key_do_regen = 0;
186 /* This is set to true when a signal is received. */
187 static volatile sig_atomic_t received_sighup = 0;
188 static volatile sig_atomic_t received_sigterm = 0;
190 /* session identifier, used by RSA-auth */
191 u_char session_id[16];
194 u_char *session_id2 = NULL;
195 int session_id2_len = 0;
197 /* record remote hostname or ip */
198 u_int utmp_len = MAXHOSTNAMELEN;
200 /* options.max_startup sized array of fd ints */
201 int *startup_pipes = NULL;
202 int startup_pipe; /* in child */
204 /* variables used for privilege separation */
205 extern struct monitor *pmonitor;
206 extern int use_privsep;
208 /* Prototypes for various functions defined later in this file. */
209 void destroy_sensitive_data(void);
210 void demote_sensitive_data(void);
212 static void do_ssh1_kex(void);
213 static void do_ssh2_kex(void);
216 * Close all listening sockets
219 close_listen_socks(void)
223 for (i = 0; i < num_listen_socks; i++)
224 close(listen_socks[i]);
225 num_listen_socks = -1;
229 close_startup_pipes(void)
234 for (i = 0; i < options.max_startups; i++)
235 if (startup_pipes[i] != -1)
236 close(startup_pipes[i]);
240 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
241 * the effect is to reread the configuration file (and to regenerate
245 sighup_handler(int sig)
247 int save_errno = errno;
250 signal(SIGHUP, sighup_handler);
255 * Called from the main program after receiving SIGHUP.
256 * Restarts the server.
261 log("Received SIGHUP; restarting.");
262 close_listen_socks();
263 close_startup_pipes();
264 execv(saved_argv[0], saved_argv);
265 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
271 * Generic signal handler for terminating signals in the master daemon.
274 sigterm_handler(int sig)
276 received_sigterm = sig;
280 * SIGCHLD handler. This is called whenever a child dies. This will then
281 * reap any zombies left by exited children.
284 main_sigchld_handler(int sig)
286 int save_errno = errno;
290 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
291 (pid < 0 && errno == EINTR))
294 signal(SIGCHLD, main_sigchld_handler);
299 * Signal handler for the alarm after the login grace period has expired.
302 grace_alarm_handler(int sig)
304 /* XXX no idea how fix this signal handler */
306 /* Close the connection. */
309 /* Log error and exit. */
310 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
314 * Signal handler for the key regeneration alarm. Note that this
315 * alarm only occurs in the daemon waiting for connections, and it does not
316 * do anything with the private key or random state before forking.
317 * Thus there should be no concurrency control/asynchronous execution
321 generate_ephemeral_server_key(void)
326 verbose("Generating %s%d bit RSA key.",
327 sensitive_data.server_key ? "new " : "", options.server_key_bits);
328 if (sensitive_data.server_key != NULL)
329 key_free(sensitive_data.server_key);
330 sensitive_data.server_key = key_generate(KEY_RSA1,
331 options.server_key_bits);
332 verbose("RSA key generation complete.");
334 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
337 sensitive_data.ssh1_cookie[i] = rand & 0xff;
344 key_regeneration_alarm(int sig)
346 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,
380 strlen(server_version_string))
381 != strlen(server_version_string)) {
382 log("Could not write ident string to %s", get_remote_ipaddr());
386 /* Read other sides version identification. */
387 memset(buf, 0, sizeof(buf));
388 for (i = 0; i < sizeof(buf) - 1; i++) {
389 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
390 log("Did not receive identification string from %s",
391 get_remote_ipaddr());
394 if (buf[i] == '\r') {
396 /* Kludge for F-Secure Macintosh < 1.0.2 */
398 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
402 if (buf[i] == '\n') {
407 buf[sizeof(buf) - 1] = 0;
408 client_version_string = xstrdup(buf);
412 * Check that the versions match. In future this might accept
413 * several versions and set appropriate flags to handle them.
415 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
416 &remote_major, &remote_minor, remote_version) != 3) {
417 s = "Protocol mismatch.\n";
418 (void) atomicio(write, sock_out, s, strlen(s));
421 log("Bad protocol version identification '%.100s' from %s",
422 client_version_string, get_remote_ipaddr());
425 debug("Client protocol version %d.%d; client software version %.100s",
426 remote_major, remote_minor, remote_version);
428 compat_datafellows(remote_version);
430 if (datafellows & SSH_BUG_SCANNER) {
431 log("scanned from %s with %s. Don't panic.",
432 get_remote_ipaddr(), client_version_string);
437 switch (remote_major) {
439 if (remote_minor == 99) {
440 if (options.protocol & SSH_PROTO_2)
446 if (!(options.protocol & SSH_PROTO_1)) {
450 if (remote_minor < 3) {
451 packet_disconnect("Your ssh version is too old and "
452 "is no longer supported. Please install a newer version.");
453 } else if (remote_minor == 3) {
454 /* note that this disables agent-forwarding */
459 if (options.protocol & SSH_PROTO_2) {
468 chop(server_version_string);
469 debug("Local version string %.200s", server_version_string);
472 s = "Protocol major versions differ.\n";
473 (void) atomicio(write, sock_out, s, strlen(s));
476 log("Protocol major versions differ for %s: %.200s vs. %.200s",
478 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 %ld", (long)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 %ld", (long)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)
691 for (i = 0; i < options.num_host_key_files; i++) {
692 Key *key = sensitive_data.host_keys[i];
693 if (key != NULL && key->type == type)
700 get_hostkey_by_index(int ind)
702 if (ind < 0 || ind >= options.num_host_key_files)
704 return (sensitive_data.host_keys[ind]);
708 get_hostkey_index(Key *key)
712 for (i = 0; i < options.num_host_key_files; i++) {
713 if (key == sensitive_data.host_keys[i])
720 * returns 1 if connection should be dropped, 0 otherwise.
721 * dropping starts at connection #max_startups_begin with a probability
722 * of (max_startups_rate/100). the probability increases linearly until
723 * all connections are dropped for startups > max_startups
726 drop_connection(int startups)
730 if (startups < options.max_startups_begin)
732 if (startups >= options.max_startups)
734 if (options.max_startups_rate == 100)
737 p = 100 - options.max_startups_rate;
738 p *= startups - options.max_startups_begin;
739 p /= (double) (options.max_startups - options.max_startups_begin);
740 p += options.max_startups_rate;
742 r = arc4random() / (double) UINT_MAX;
744 debug("drop_connection: p %g, r %g", p, r);
745 return (r < p) ? 1 : 0;
751 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
752 fprintf(stderr, "Usage: %s [options]\n", __progname);
753 fprintf(stderr, "Options:\n");
754 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
755 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
756 fprintf(stderr, " -i Started from inetd\n");
757 fprintf(stderr, " -D Do not fork into daemon mode\n");
758 fprintf(stderr, " -t Only test configuration file and keys\n");
759 fprintf(stderr, " -q Quiet (no logging)\n");
760 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
761 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
762 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
763 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
764 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
765 _PATH_HOST_KEY_FILE);
766 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
767 fprintf(stderr, " -4 Use IPv4 only\n");
768 fprintf(stderr, " -6 Use IPv6 only\n");
769 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
774 * Main program for the daemon.
777 main(int ac, char **av)
781 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
785 struct sockaddr_storage from;
786 const char *remote_ip;
789 struct linger linger;
791 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
792 int listen_sock, maxfd;
797 int ret, key_used = 0;
799 #ifdef HAVE_SECUREWARE
800 (void)set_auth_parameters(ac, av);
802 __progname = get_progname(av[0]);
809 /* Initialize configuration options to their default values. */
810 initialize_server_options(&options);
812 /* Parse command-line arguments. */
813 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
822 config_file_name = optarg;
825 if (0 == debug_flag) {
827 options.log_level = SYSLOG_LEVEL_DEBUG1;
828 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
831 fprintf(stderr, "Too high debugging level.\n");
848 options.log_level = SYSLOG_LEVEL_QUIET;
851 options.server_key_bits = atoi(optarg);
854 options.ports_from_cmdline = 1;
855 if (options.num_ports >= MAX_PORTS) {
856 fprintf(stderr, "too many ports.\n");
859 options.ports[options.num_ports++] = a2port(optarg);
860 if (options.ports[options.num_ports-1] == 0) {
861 fprintf(stderr, "Bad port number.\n");
866 if ((options.login_grace_time = convtime(optarg)) == -1) {
867 fprintf(stderr, "Invalid login grace time.\n");
872 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
873 fprintf(stderr, "Invalid key regeneration interval.\n");
878 if (options.num_host_key_files >= MAX_HOSTKEYS) {
879 fprintf(stderr, "too many host keys.\n");
882 options.host_key_files[options.num_host_key_files++] = optarg;
885 client_version_string = optarg;
886 /* only makes sense with inetd_flag, i.e. no listen() */
893 utmp_len = atoi(optarg);
896 if (process_server_config_line(&options, optarg,
897 "command-line", 0) != 0)
906 SSLeay_add_all_algorithms();
907 channel_set_af(IPv4or6);
910 * Force logging to stderr until we have loaded the private host
911 * key (unless started from inetd)
914 options.log_level == SYSLOG_LEVEL_NOT_SET ?
915 SYSLOG_LEVEL_INFO : options.log_level,
916 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
917 SYSLOG_FACILITY_AUTH : options.log_facility,
921 /* Cray can define user privs drop all prives now!
922 * Not needed on PRIV_SU systems!
929 /* Read server configuration options from the configuration file. */
930 read_server_config(&options, config_file_name);
932 /* Fill in default values for those options not explicitly set. */
933 fill_default_server_options(&options);
935 /* Check that there are no remaining arguments. */
937 fprintf(stderr, "Extra argument %s.\n", av[optind]);
941 debug("sshd version %.100s", SSH_VERSION);
943 /* load private host keys */
944 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
945 for (i = 0; i < options.num_host_key_files; i++)
946 sensitive_data.host_keys[i] = NULL;
947 sensitive_data.server_key = NULL;
948 sensitive_data.ssh1_host_key = NULL;
949 sensitive_data.have_ssh1_key = 0;
950 sensitive_data.have_ssh2_key = 0;
952 for (i = 0; i < options.num_host_key_files; i++) {
953 key = key_load_private(options.host_key_files[i], "", NULL);
954 sensitive_data.host_keys[i] = key;
956 error("Could not load host key: %s",
957 options.host_key_files[i]);
958 sensitive_data.host_keys[i] = NULL;
963 sensitive_data.ssh1_host_key = key;
964 sensitive_data.have_ssh1_key = 1;
968 sensitive_data.have_ssh2_key = 1;
971 debug("private host key: #%d type %d %s", i, key->type,
974 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
975 log("Disabling protocol version 1. Could not load host key");
976 options.protocol &= ~SSH_PROTO_1;
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;
982 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
983 log("sshd: no hostkeys available -- exiting.");
987 /* Check certain values for sanity. */
988 if (options.protocol & SSH_PROTO_1) {
989 if (options.server_key_bits < 512 ||
990 options.server_key_bits > 32768) {
991 fprintf(stderr, "Bad server key size.\n");
995 * Check that server and host key lengths differ sufficiently. This
996 * is necessary to make double encryption work with rsaref. Oh, I
997 * hate software patents. I dont know if this can go? Niels
999 if (options.server_key_bits >
1000 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1001 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1002 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1003 SSH_KEY_BITS_RESERVED) {
1004 options.server_key_bits =
1005 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1006 SSH_KEY_BITS_RESERVED;
1007 debug("Forcing server key to %d bits to make it differ from host key.",
1008 options.server_key_bits);
1016 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1017 fatal("Privilege separation user %s does not exist",
1019 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1020 (S_ISDIR(st.st_mode) == 0))
1021 fatal("Missing privilege separation directory: %s",
1022 _PATH_PRIVSEP_CHROOT_DIR);
1023 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1024 fatal("Bad owner or mode for %s",
1025 _PATH_PRIVSEP_CHROOT_DIR);
1028 /* Configuration looks good, so exit if in test mode. */
1033 * Clear out any supplemental groups we may have inherited. This
1034 * prevents inadvertent creation of files with bad modes (in the
1035 * portable version at least, it's certainly possible for PAM
1036 * to create a file, and we can't control the code in every
1037 * module which might be used).
1039 if (setgroups(0, NULL) < 0)
1040 debug("setgroups() failed: %.200s", strerror(errno));
1042 /* Initialize the log (it is reinitialized below in case we forked). */
1043 if (debug_flag && !inetd_flag)
1045 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1048 * If not in debugging mode, and not started from inetd, disconnect
1049 * from the controlling terminal, and fork. The original process
1052 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1055 #endif /* TIOCNOTTY */
1056 if (daemon(0, 0) < 0)
1057 fatal("daemon() failed: %.200s", strerror(errno));
1059 /* Disconnect from the controlling tty. */
1061 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1063 (void) ioctl(fd, TIOCNOTTY, NULL);
1066 #endif /* TIOCNOTTY */
1068 /* Reinitialize the log (because of the fork above). */
1069 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1071 /* Initialize the random number generator. */
1074 /* Chdir to the root directory so that the current disk can be
1075 unmounted if desired. */
1078 /* ignore SIGPIPE */
1079 signal(SIGPIPE, SIG_IGN);
1081 /* Start listening for a socket, unless started from inetd. */
1084 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1090 * We intentionally do not close the descriptors 0, 1, and 2
1091 * as our code for setting the descriptors won\'t work if
1092 * ttyfd happens to be one of those.
1094 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1095 if (options.protocol & SSH_PROTO_1)
1096 generate_ephemeral_server_key();
1098 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1099 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1101 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1102 fatal("Too many listen sockets. "
1103 "Enlarge MAX_LISTEN_SOCKS");
1104 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1105 ntop, sizeof(ntop), strport, sizeof(strport),
1106 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1107 error("getnameinfo failed");
1110 /* Create socket for listening. */
1111 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
1112 if (listen_sock < 0) {
1113 /* kernel may not support ipv6 */
1114 verbose("socket: %.100s", strerror(errno));
1117 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1118 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1123 * Set socket options. We try to make the port
1124 * reusable and have it close as fast as possible
1125 * without waiting in unnecessary wait states on
1128 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1131 linger.l_linger = 5;
1132 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
1133 &linger, sizeof(linger));
1135 debug("Bind to port %s on %s.", strport, ntop);
1137 /* Bind the socket to the desired port. */
1138 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1140 error("Bind to port %s on %s failed: %.200s.",
1141 strport, ntop, strerror(errno));
1145 listen_socks[num_listen_socks] = listen_sock;
1148 /* Start listening on the port. */
1149 log("Server listening on %s port %s.", ntop, strport);
1150 if (listen(listen_sock, 5) < 0)
1151 fatal("listen: %.100s", strerror(errno));
1154 freeaddrinfo(options.listen_addrs);
1156 if (!num_listen_socks)
1157 fatal("Cannot bind any address.");
1159 if (options.protocol & SSH_PROTO_1)
1160 generate_ephemeral_server_key();
1163 * Arrange to restart on SIGHUP. The handler needs
1166 signal(SIGHUP, sighup_handler);
1168 signal(SIGTERM, sigterm_handler);
1169 signal(SIGQUIT, sigterm_handler);
1171 /* Arrange SIGCHLD to be caught. */
1172 signal(SIGCHLD, main_sigchld_handler);
1174 /* Write out the pid file after the sigterm handler is setup */
1177 * Record our pid in /var/run/sshd.pid to make it
1178 * easier to kill the correct sshd. We don't want to
1179 * do this before the bind above because the bind will
1180 * fail if there already is a daemon, and this will
1181 * overwrite any old pid in the file.
1183 f = fopen(options.pid_file, "wb");
1185 fprintf(f, "%ld\n", (long) getpid());
1190 /* setup fd set for listen */
1193 for (i = 0; i < num_listen_socks; i++)
1194 if (listen_socks[i] > maxfd)
1195 maxfd = listen_socks[i];
1196 /* pipes connected to unauthenticated childs */
1197 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1198 for (i = 0; i < options.max_startups; i++)
1199 startup_pipes[i] = -1;
1202 * Stay listening for connections until the system crashes or
1203 * the daemon is killed with a signal.
1206 if (received_sighup)
1210 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1211 fdset = (fd_set *)xmalloc(fdsetsz);
1212 memset(fdset, 0, fdsetsz);
1214 for (i = 0; i < num_listen_socks; i++)
1215 FD_SET(listen_socks[i], fdset);
1216 for (i = 0; i < options.max_startups; i++)
1217 if (startup_pipes[i] != -1)
1218 FD_SET(startup_pipes[i], fdset);
1220 /* Wait in select until there is a connection. */
1221 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1222 if (ret < 0 && errno != EINTR)
1223 error("select: %.100s", strerror(errno));
1224 if (received_sigterm) {
1225 log("Received signal %d; terminating.",
1226 (int) received_sigterm);
1227 close_listen_socks();
1228 unlink(options.pid_file);
1231 if (key_used && key_do_regen) {
1232 generate_ephemeral_server_key();
1239 for (i = 0; i < options.max_startups; i++)
1240 if (startup_pipes[i] != -1 &&
1241 FD_ISSET(startup_pipes[i], fdset)) {
1243 * the read end of the pipe is ready
1244 * if the child has closed the pipe
1245 * after successful authentication
1246 * or if the child has died
1248 close(startup_pipes[i]);
1249 startup_pipes[i] = -1;
1252 for (i = 0; i < num_listen_socks; i++) {
1253 if (!FD_ISSET(listen_socks[i], fdset))
1255 fromlen = sizeof(from);
1256 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1259 if (errno != EINTR && errno != EWOULDBLOCK)
1260 error("accept: %.100s", strerror(errno));
1263 if (fcntl(newsock, F_SETFL, 0) < 0) {
1264 error("newsock del O_NONBLOCK: %s", strerror(errno));
1268 if (drop_connection(startups) == 1) {
1269 debug("drop connection #%d", startups);
1273 if (pipe(startup_p) == -1) {
1278 for (j = 0; j < options.max_startups; j++)
1279 if (startup_pipes[j] == -1) {
1280 startup_pipes[j] = startup_p[0];
1281 if (maxfd < startup_p[0])
1282 maxfd = startup_p[0];
1288 * Got connection. Fork a child to handle it, unless
1289 * we are in debugging mode.
1293 * In debugging mode. Close the listening
1294 * socket, and start processing the
1295 * connection without forking.
1297 debug("Server will not fork when running in debugging mode.");
1298 close_listen_socks();
1306 * Normal production daemon. Fork, and have
1307 * the child process the connection. The
1308 * parent continues listening.
1310 if ((pid = fork()) == 0) {
1312 * Child. Close the listening and max_startup
1313 * sockets. Start using the accepted socket.
1314 * Reinitialize logging (since our pid has
1315 * changed). We break out of the loop to handle
1318 startup_pipe = startup_p[1];
1319 close_startup_pipes();
1320 close_listen_socks();
1323 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1328 /* Parent. Stay in the loop. */
1330 error("fork: %.100s", strerror(errno));
1332 debug("Forked child %ld.", (long)pid);
1334 close(startup_p[1]);
1336 /* Mark that the key has been used (it was "given" to the child). */
1337 if ((options.protocol & SSH_PROTO_1) &&
1339 /* Schedule server key regeneration alarm. */
1340 signal(SIGALRM, key_regeneration_alarm);
1341 alarm(options.key_regeneration_time);
1347 /* Close the new socket (the child is now taking care of it). */
1350 /* child process check (or debug mode) */
1351 if (num_listen_socks < 0)
1356 /* This is the child processing a new connection. */
1359 * Create a new session and process group since the 4.4BSD
1360 * setlogin() affects the entire process group. We don't
1361 * want the child to be able to affect the parent.
1364 /* XXX: this breaks Solaris */
1365 if (!debug_flag && !inetd_flag && setsid() < 0)
1366 error("setsid: %.100s", strerror(errno));
1370 * Disable the key regeneration alarm. We will not regenerate the
1371 * key since we are no longer in a position to give it to anyone. We
1372 * will not restart on SIGHUP since it no longer makes sense.
1375 signal(SIGALRM, SIG_DFL);
1376 signal(SIGHUP, SIG_DFL);
1377 signal(SIGTERM, SIG_DFL);
1378 signal(SIGQUIT, SIG_DFL);
1379 signal(SIGCHLD, SIG_DFL);
1380 signal(SIGINT, SIG_DFL);
1383 * Set socket options for the connection. We want the socket to
1384 * close as fast as possible without waiting for anything. If the
1385 * connection is not a socket, these will do nothing.
1387 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1389 linger.l_linger = 5;
1390 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
1392 /* Set keepalives if requested. */
1393 if (options.keepalives &&
1394 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1396 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1399 * Register our connection. This turns encryption off because we do
1402 packet_set_connection(sock_in, sock_out);
1404 remote_port = get_remote_port();
1405 remote_ip = get_remote_ipaddr();
1408 /* Check whether logins are denied from this host. */
1410 struct request_info req;
1412 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1415 if (!hosts_access(&req)) {
1416 debug("Connection refused by tcp wrapper");
1419 fatal("libwrap refuse returns");
1422 #endif /* LIBWRAP */
1424 /* Log the connection. */
1425 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1428 * We don\'t want to listen forever unless the other side
1429 * successfully authenticates itself. So we set up an alarm which is
1430 * cleared after successful authentication. A limit of zero
1431 * indicates no limit. Note that we don\'t set the alarm in debugging
1432 * mode; it is just annoying to have the server exit just when you
1433 * are about to discover the bug.
1435 signal(SIGALRM, grace_alarm_handler);
1437 alarm(options.login_grace_time);
1439 sshd_exchange_identification(sock_in, sock_out);
1441 * Check that the connection comes from a privileged port.
1442 * Rhosts-Authentication only makes sense from privileged
1443 * programs. Of course, if the intruder has root access on his local
1444 * machine, he can connect from any port. So do not use these
1445 * authentication methods from machines that you do not trust.
1447 if (options.rhosts_authentication &&
1448 (remote_port >= IPPORT_RESERVED ||
1449 remote_port < IPPORT_RESERVED / 2)) {
1450 debug("Rhosts Authentication disabled, "
1451 "originating port %d not trusted.", remote_port);
1452 options.rhosts_authentication = 0;
1454 #if defined(KRB4) && !defined(KRB5)
1455 if (!packet_connection_is_ipv4() &&
1456 options.kerberos_authentication) {
1457 debug("Kerberos Authentication disabled, only available for IPv4.");
1458 options.kerberos_authentication = 0;
1460 #endif /* KRB4 && !KRB5 */
1462 /* If machine has AFS, set process authentication group. */
1469 packet_set_nonblocking();
1472 if ((authctxt = privsep_preauth()) != NULL)
1475 /* perform the key exchange */
1476 /* authenticate user and start session */
1479 authctxt = do_authentication2();
1482 authctxt = do_authentication();
1485 * If we use privilege separation, the unprivileged child transfers
1486 * the current keystate and exits
1489 mm_send_keystate(pmonitor);
1495 * In privilege separation, we fork another child and prepare
1496 * file descriptor passing.
1499 privsep_postauth(authctxt);
1500 /* the monitor process [priv] will not return */
1502 destroy_sensitive_data();
1505 /* Perform session preparation. */
1506 do_authenticated(authctxt);
1508 /* The connection has been terminated. */
1509 verbose("Closing connection to %.100s", remote_ip);
1513 #endif /* USE_PAM */
1524 * Decrypt session_key_int using our private server key and private host key
1525 * (key with larger modulus first).
1528 ssh1_session_key(BIGNUM *session_key_int)
1532 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1533 /* Server key has bigger modulus. */
1534 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1535 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1536 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1537 get_remote_ipaddr(),
1538 BN_num_bits(sensitive_data.server_key->rsa->n),
1539 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1540 SSH_KEY_BITS_RESERVED);
1542 if (rsa_private_decrypt(session_key_int, session_key_int,
1543 sensitive_data.server_key->rsa) <= 0)
1545 if (rsa_private_decrypt(session_key_int, session_key_int,
1546 sensitive_data.ssh1_host_key->rsa) <= 0)
1549 /* Host key has bigger modulus (or they are equal). */
1550 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1551 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1552 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1553 get_remote_ipaddr(),
1554 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1555 BN_num_bits(sensitive_data.server_key->rsa->n),
1556 SSH_KEY_BITS_RESERVED);
1558 if (rsa_private_decrypt(session_key_int, session_key_int,
1559 sensitive_data.ssh1_host_key->rsa) < 0)
1561 if (rsa_private_decrypt(session_key_int, session_key_int,
1562 sensitive_data.server_key->rsa) < 0)
1575 BIGNUM *session_key_int;
1576 u_char session_key[SSH_SESSION_KEY_LENGTH];
1578 u_int cipher_type, auth_mask, protocol_flags;
1582 * Generate check bytes that the client must send back in the user
1583 * packet in order for it to be accepted; this is used to defy ip
1584 * spoofing attacks. Note that this only works against somebody
1585 * doing IP spoofing from a remote machine; any machine on the local
1586 * network can still see outgoing packets and catch the random
1587 * cookie. This only affects rhosts authentication, and this is one
1588 * of the reasons why it is inherently insecure.
1590 for (i = 0; i < 8; i++) {
1592 rand = arc4random();
1593 cookie[i] = rand & 0xff;
1598 * Send our public key. We include in the packet 64 bits of random
1599 * data that must be matched in the reply in order to prevent IP
1602 packet_start(SSH_SMSG_PUBLIC_KEY);
1603 for (i = 0; i < 8; i++)
1604 packet_put_char(cookie[i]);
1606 /* Store our public server RSA key. */
1607 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1608 packet_put_bignum(sensitive_data.server_key->rsa->e);
1609 packet_put_bignum(sensitive_data.server_key->rsa->n);
1611 /* Store our public host RSA key. */
1612 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1613 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1614 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1616 /* Put protocol flags. */
1617 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1619 /* Declare which ciphers we support. */
1620 packet_put_int(cipher_mask_ssh1(0));
1622 /* Declare supported authentication types. */
1624 if (options.rhosts_authentication)
1625 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1626 if (options.rhosts_rsa_authentication)
1627 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1628 if (options.rsa_authentication)
1629 auth_mask |= 1 << SSH_AUTH_RSA;
1630 #if defined(KRB4) || defined(KRB5)
1631 if (options.kerberos_authentication)
1632 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1634 #if defined(AFS) || defined(KRB5)
1635 if (options.kerberos_tgt_passing)
1636 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1639 if (options.afs_token_passing)
1640 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1642 if (options.challenge_response_authentication == 1)
1643 auth_mask |= 1 << SSH_AUTH_TIS;
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];
1735 /* Destroy the private and public keys. No longer. */
1736 destroy_sensitive_data();
1739 mm_ssh1_session_id(session_id);
1741 /* Destroy the decrypted integer. It is no longer needed. */
1742 BN_clear_free(session_key_int);
1744 /* Set the session key. From this on all communications will be encrypted. */
1745 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1747 /* Destroy our copy of the session key. It is no longer needed. */
1748 memset(session_key, 0, sizeof(session_key));
1750 debug("Received session key; encryption turned on.");
1752 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1753 packet_start(SSH_SMSG_SUCCESS);
1755 packet_write_wait();
1759 * SSH2 key exchange: diffie-hellman-group1-sha1
1766 if (options.ciphers != NULL) {
1767 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1768 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1770 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1771 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1772 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1773 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1775 if (options.macs != NULL) {
1776 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1777 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1779 if (!options.compression) {
1780 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1781 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1783 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1785 /* start key exchange */
1786 kex = kex_setup(myproposal);
1788 kex->client_version_string=client_version_string;
1789 kex->server_version_string=server_version_string;
1790 kex->load_host_key=&get_hostkey_by_type;
1791 kex->host_key_index=&get_hostkey_index;
1795 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1797 session_id2 = kex->session_id;
1798 session_id2_len = kex->session_id_len;
1801 /* send 1st encrypted/maced/compressed message */
1802 packet_start(SSH2_MSG_IGNORE);
1803 packet_put_cstring("markus");
1805 packet_write_wait();