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:
19 * Copyright (c) 2000 Markus Friedl. All rights reserved.
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
24 * 1. Redistributions of source code must retain the above copyright
25 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in the
28 * documentation and/or other materials provided with the distribution.
30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
31 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
33 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
34 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
35 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
39 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43 RCSID("$OpenBSD: sshd.c,v 1.163 2001/02/04 23:56:23 deraadt Exp $");
45 #include <openssl/dh.h>
46 #include <openssl/bn.h>
47 #include <openssl/hmac.h>
66 #include "myproposal.h"
68 #include "pathnames.h"
77 int allow_severity = LOG_INFO;
78 int deny_severity = LOG_WARNING;
85 #ifdef HAVE___PROGNAME
86 extern char *__progname;
91 /* Server configuration options. */
92 ServerOptions options;
94 /* Name of the server configuration file. */
95 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
98 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
99 * Default value is AF_UNSPEC means both IPv4 and IPv6.
102 int IPv4or6 = AF_INET;
104 int IPv4or6 = AF_UNSPEC;
108 * Debug mode flag. This can be set on the command line. If debug
109 * mode is enabled, extra debugging output will be sent to the system
110 * log, the daemon will not go to background, and will exit after processing
111 * the first connection.
115 /* Flag indicating that the daemon is being started from inetd. */
118 /* Flag indicating that sshd should not detach and become a daemon. */
119 int no_daemon_flag = 0;
121 /* debug goes to stderr unless inetd_flag is set */
124 /* Saved arguments to main(). */
129 * The sockets that the server is listening; this is used in the SIGHUP
132 #define MAX_LISTEN_SOCKS 16
133 int listen_socks[MAX_LISTEN_SOCKS];
134 int num_listen_socks = 0;
137 * the client's version string, passed by sshd2 in compat mode. if != NULL,
138 * sshd will skip the version-number exchange
140 char *client_version_string = NULL;
141 char *server_version_string = NULL;
144 * Any really sensitive data in the application is contained in this
145 * structure. The idea is that this structure could be locked into memory so
146 * that the pages do not get written into swap. However, there are some
147 * problems. The private key contains BIGNUMs, and we do not (in principle)
148 * have access to the internals of them, and locking just the structure is
149 * not very useful. Currently, memory locking is not implemented.
152 Key *server_key; /* empheral server key */
153 Key *ssh1_host_key; /* ssh1 host key */
154 Key **host_keys; /* all private host keys */
160 * Flag indicating whether the RSA server key needs to be regenerated.
161 * Is set in the SIGALRM handler and cleared when the key is regenerated.
163 int key_do_regen = 0;
165 /* This is set to true when SIGHUP is received. */
166 int received_sighup = 0;
168 /* session identifier, used by RSA-auth */
169 u_char session_id[16];
172 u_char *session_id2 = NULL;
173 int session_id2_len = 0;
175 /* record remote hostname or ip */
176 u_int utmp_len = MAXHOSTNAMELEN;
178 /* Prototypes for various functions defined later in this file. */
179 void do_ssh1_kex(void);
180 void do_ssh2_kex(void);
182 void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
183 void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
186 * Close all listening sockets
189 close_listen_socks(void)
192 for (i = 0; i < num_listen_socks; i++)
193 close(listen_socks[i]);
194 num_listen_socks = -1;
198 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
199 * the effect is to reread the configuration file (and to regenerate
203 sighup_handler(int sig)
206 signal(SIGHUP, sighup_handler);
210 * Called from the main program after receiving SIGHUP.
211 * Restarts the server.
216 log("Received SIGHUP; restarting.");
217 close_listen_socks();
218 execv(saved_argv[0], saved_argv);
219 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
224 * Generic signal handler for terminating signals in the master daemon.
225 * These close the listen socket; not closing it seems to cause "Address
226 * already in use" problems on some machines, which is inconvenient.
229 sigterm_handler(int sig)
231 log("Received signal %d; terminating.", sig);
232 close_listen_socks();
233 unlink(options.pid_file);
238 * SIGCHLD handler. This is called whenever a child dies. This will then
239 * reap any zombies left by exited c.
242 main_sigchld_handler(int sig)
244 int save_errno = errno;
247 while (waitpid(-1, &status, WNOHANG) > 0)
250 signal(SIGCHLD, main_sigchld_handler);
255 * Signal handler for the alarm after the login grace period has expired.
258 grace_alarm_handler(int sig)
260 /* Close the connection. */
263 /* Log error and exit. */
264 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
268 * Signal handler for the key regeneration alarm. Note that this
269 * alarm only occurs in the daemon waiting for connections, and it does not
270 * do anything with the private key or random state before forking.
271 * Thus there should be no concurrency control/asynchronous execution
275 generate_empheral_server_key(void)
277 log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "",
278 options.server_key_bits);
279 if (sensitive_data.server_key != NULL)
280 key_free(sensitive_data.server_key);
281 sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits);
283 log("RSA key generation complete.");
287 key_regeneration_alarm(int sig)
289 int save_errno = errno;
290 signal(SIGALRM, SIG_DFL);
296 sshd_exchange_identification(int sock_in, int sock_out)
299 int remote_major, remote_minor;
302 char buf[256]; /* Must not be larger than remote_version. */
303 char remote_version[256]; /* Must be at least as big as buf. */
305 if ((options.protocol & SSH_PROTO_1) &&
306 (options.protocol & SSH_PROTO_2)) {
307 major = PROTOCOL_MAJOR_1;
309 } else if (options.protocol & SSH_PROTO_2) {
310 major = PROTOCOL_MAJOR_2;
311 minor = PROTOCOL_MINOR_2;
313 major = PROTOCOL_MAJOR_1;
314 minor = PROTOCOL_MINOR_1;
316 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
317 server_version_string = xstrdup(buf);
319 if (client_version_string == NULL) {
320 /* Send our protocol version identification. */
321 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
322 != strlen(server_version_string)) {
323 log("Could not write ident string to %s.", get_remote_ipaddr());
327 /* Read other side\'s version identification. */
328 for (i = 0; i < sizeof(buf) - 1; i++) {
329 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
330 log("Did not receive ident string from %s.", get_remote_ipaddr());
333 if (buf[i] == '\r') {
336 /* Kludge for F-Secure Macintosh < 1.0.2 */
338 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
342 if (buf[i] == '\n') {
348 buf[sizeof(buf) - 1] = 0;
349 client_version_string = xstrdup(buf);
353 * Check that the versions match. In future this might accept
354 * several versions and set appropriate flags to handle them.
356 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
357 &remote_major, &remote_minor, remote_version) != 3) {
358 s = "Protocol mismatch.\n";
359 (void) atomicio(write, sock_out, s, strlen(s));
362 log("Bad protocol version identification '%.100s' from %s",
363 client_version_string, get_remote_ipaddr());
366 debug("Client protocol version %d.%d; client software version %.100s",
367 remote_major, remote_minor, remote_version);
369 compat_datafellows(remote_version);
372 switch(remote_major) {
374 if (remote_minor == 99) {
375 if (options.protocol & SSH_PROTO_2)
381 if (!(options.protocol & SSH_PROTO_1)) {
385 if (remote_minor < 3) {
386 packet_disconnect("Your ssh version is too old and "
387 "is no longer supported. Please install a newer version.");
388 } else if (remote_minor == 3) {
389 /* note that this disables agent-forwarding */
394 if (options.protocol & SSH_PROTO_2) {
403 chop(server_version_string);
404 chop(client_version_string);
405 debug("Local version string %.200s", server_version_string);
408 s = "Protocol major versions differ.\n";
409 (void) atomicio(write, sock_out, s, strlen(s));
412 log("Protocol major versions differ for %s: %.200s vs. %.200s",
414 server_version_string, client_version_string);
418 packet_set_ssh2_format();
422 /* Destroy the host and server keys. They will no longer be needed. */
424 destroy_sensitive_data(void)
428 if (sensitive_data.server_key) {
429 key_free(sensitive_data.server_key);
430 sensitive_data.server_key = NULL;
432 for(i = 0; i < options.num_host_key_files; i++) {
433 if (sensitive_data.host_keys[i]) {
434 key_free(sensitive_data.host_keys[i]);
435 sensitive_data.host_keys[i] = NULL;
438 sensitive_data.ssh1_host_key = NULL;
441 load_private_key_autodetect(const char *filename)
445 Key *public, *private;
447 if (stat(filename, &st) < 0) {
452 * try to load the public key. right now this only works for RSA1,
453 * since SSH2 keys are fully encrypted
456 public = key_new(type);
457 if (!load_public_key(filename, public, NULL)) {
458 /* ok, so we will assume this is 'some' key */
463 /* Ok, try key with empty passphrase */
464 private = key_new(type);
465 if (load_private_key(filename, "", private, NULL)) {
466 debug("load_private_key_autodetect: type %d %s",
467 private->type, key_type(private));
475 list_hostkey_types(void)
477 static char buf[1024];
480 for(i = 0; i < options.num_host_key_files; i++) {
481 Key *key = sensitive_data.host_keys[i];
487 strlcat(buf, key_ssh_name(key), sizeof buf);
488 strlcat(buf, ",", sizeof buf);
493 if (i > 0 && buf[i-1] == ',')
495 debug("list_hostkey_types: %s", buf);
500 get_hostkey_by_type(int type)
503 for(i = 0; i < options.num_host_key_files; i++) {
504 Key *key = sensitive_data.host_keys[i];
505 if (key != NULL && key->type == type)
512 * returns 1 if connection should be dropped, 0 otherwise.
513 * dropping starts at connection #max_startups_begin with a probability
514 * of (max_startups_rate/100). the probability increases linearly until
515 * all connections are dropped for startups > max_startups
518 drop_connection(int startups)
522 if (startups < options.max_startups_begin)
524 if (startups >= options.max_startups)
526 if (options.max_startups_rate == 100)
529 p = 100 - options.max_startups_rate;
530 p *= startups - options.max_startups_begin;
531 p /= (double) (options.max_startups - options.max_startups_begin);
532 p += options.max_startups_rate;
534 r = arc4random() / (double) UINT_MAX;
536 debug("drop_connection: p %g, r %g", p, r);
537 return (r < p) ? 1 : 0;
540 int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
541 int startup_pipe; /* in child */
544 * Main program for the daemon.
547 main(int ac, char **av)
551 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
555 struct sockaddr_storage from;
556 const char *remote_ip;
559 struct linger linger;
561 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
562 int listen_sock, maxfd;
565 int ret, key_used = 0;
567 __progname = get_progname(av[0]);
574 /* Initialize configuration options to their default values. */
575 initialize_server_options(&options);
577 /* Parse command-line arguments. */
578 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
587 config_file_name = optarg;
590 if (0 == debug_flag) {
592 options.log_level = SYSLOG_LEVEL_DEBUG1;
593 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
596 fprintf(stderr, "Too high debugging level.\n");
610 options.log_level = SYSLOG_LEVEL_QUIET;
613 options.server_key_bits = atoi(optarg);
616 options.ports_from_cmdline = 1;
617 if (options.num_ports >= MAX_PORTS) {
618 fprintf(stderr, "too many ports.\n");
621 options.ports[options.num_ports++] = atoi(optarg);
624 options.login_grace_time = atoi(optarg);
627 options.key_regeneration_time = atoi(optarg);
630 if (options.num_host_key_files >= MAX_HOSTKEYS) {
631 fprintf(stderr, "too many host keys.\n");
634 options.host_key_files[options.num_host_key_files++] = optarg;
637 client_version_string = optarg;
638 /* only makes sense with inetd_flag, i.e. no listen() */
642 utmp_len = atoi(optarg);
646 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
647 fprintf(stderr, "Usage: %s [options]\n", __progname);
648 fprintf(stderr, "Options:\n");
649 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
650 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
651 fprintf(stderr, " -i Started from inetd\n");
652 fprintf(stderr, " -D Do not fork into daemon mode\n");
653 fprintf(stderr, " -q Quiet (no logging)\n");
654 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
655 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
656 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
657 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
658 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
659 _PATH_HOST_KEY_FILE);
660 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
661 fprintf(stderr, " -4 Use IPv4 only\n");
662 fprintf(stderr, " -6 Use IPv6 only\n");
668 * Force logging to stderr until we have loaded the private host
669 * key (unless started from inetd)
672 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
673 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
676 /* Read server configuration options from the configuration file. */
677 read_server_config(&options, config_file_name);
679 /* Fill in default values for those options not explicitly set. */
680 fill_default_server_options(&options);
682 /* Check that there are no remaining arguments. */
684 fprintf(stderr, "Extra argument %s.\n", av[optind]);
688 debug("sshd version %.100s", SSH_VERSION);
690 /* load private host keys */
691 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
692 for(i = 0; i < options.num_host_key_files; i++)
693 sensitive_data.host_keys[i] = NULL;
694 sensitive_data.server_key = NULL;
695 sensitive_data.ssh1_host_key = NULL;
696 sensitive_data.have_ssh1_key = 0;
697 sensitive_data.have_ssh2_key = 0;
699 for(i = 0; i < options.num_host_key_files; i++) {
700 Key *key = load_private_key_autodetect(options.host_key_files[i]);
702 error("Could not load host key: %.200s: %.100s",
703 options.host_key_files[i], strerror(errno));
708 sensitive_data.ssh1_host_key = key;
709 sensitive_data.have_ssh1_key = 1;
713 sensitive_data.have_ssh2_key = 1;
716 sensitive_data.host_keys[i] = key;
718 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
719 log("Disabling protocol version 1. Could not load host key");
720 options.protocol &= ~SSH_PROTO_1;
722 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
723 log("Disabling protocol version 2. Could not load host key");
724 options.protocol &= ~SSH_PROTO_2;
726 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
727 log("sshd: no hostkeys available -- exiting.\n");
731 /* Check certain values for sanity. */
732 if (options.protocol & SSH_PROTO_1) {
733 if (options.server_key_bits < 512 ||
734 options.server_key_bits > 32768) {
735 fprintf(stderr, "Bad server key size.\n");
739 * Check that server and host key lengths differ sufficiently. This
740 * is necessary to make double encryption work with rsaref. Oh, I
741 * hate software patents. I dont know if this can go? Niels
743 if (options.server_key_bits >
744 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
745 options.server_key_bits <
746 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
747 options.server_key_bits =
748 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
749 debug("Forcing server key to %d bits to make it differ from host key.",
750 options.server_key_bits);
754 #ifdef HAVE_SCO_PROTECTED_PW
755 (void) set_auth_parameters(ac, av);
758 /* Initialize the log (it is reinitialized below in case we forked). */
759 if (debug_flag && !inetd_flag)
761 log_init(__progname, options.log_level, options.log_facility, log_stderr);
764 * If not in debugging mode, and not started from inetd, disconnect
765 * from the controlling terminal, and fork. The original process
768 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
771 #endif /* TIOCNOTTY */
772 if (daemon(0, 0) < 0)
773 fatal("daemon() failed: %.200s", strerror(errno));
775 /* Disconnect from the controlling tty. */
777 fd = open("/dev/tty", O_RDWR | O_NOCTTY);
779 (void) ioctl(fd, TIOCNOTTY, NULL);
782 #endif /* TIOCNOTTY */
784 /* Reinitialize the log (because of the fork above). */
785 log_init(__progname, options.log_level, options.log_facility, log_stderr);
787 /* Initialize the random number generator. */
790 /* Chdir to the root directory so that the current disk can be
791 unmounted if desired. */
794 /* Start listening for a socket, unless started from inetd. */
797 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
803 * We intentionally do not close the descriptors 0, 1, and 2
804 * as our code for setting the descriptors won\'t work if
805 * ttyfd happens to be one of those.
807 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
808 if (options.protocol & SSH_PROTO_1)
809 generate_empheral_server_key();
811 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
812 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
814 if (num_listen_socks >= MAX_LISTEN_SOCKS)
815 fatal("Too many listen sockets. "
816 "Enlarge MAX_LISTEN_SOCKS");
817 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
818 ntop, sizeof(ntop), strport, sizeof(strport),
819 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
820 error("getnameinfo failed");
823 /* Create socket for listening. */
824 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
825 if (listen_sock < 0) {
826 /* kernel may not support ipv6 */
827 verbose("socket: %.100s", strerror(errno));
830 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
831 error("listen_sock O_NONBLOCK: %s", strerror(errno));
836 * Set socket options. We try to make the port
837 * reusable and have it close as fast as possible
838 * without waiting in unnecessary wait states on
841 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
842 (void *) &on, sizeof(on));
845 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
846 (void *) &linger, sizeof(linger));
848 debug("Bind to port %s on %s.", strport, ntop);
850 /* Bind the socket to the desired port. */
851 if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) &&
853 error("Bind to port %s on %s failed: %.200s.",
854 strport, ntop, strerror(errno));
858 listen_socks[num_listen_socks] = listen_sock;
861 /* Start listening on the port. */
862 log("Server listening on %s port %s.", ntop, strport);
863 if (listen(listen_sock, 5) < 0)
864 fatal("listen: %.100s", strerror(errno));
867 freeaddrinfo(options.listen_addrs);
869 if (!num_listen_socks)
870 fatal("Cannot bind any address.");
874 * Record our pid in /var/run/sshd.pid to make it
875 * easier to kill the correct sshd. We don't want to
876 * do this before the bind above because the bind will
877 * fail if there already is a daemon, and this will
878 * overwrite any old pid in the file.
880 f = fopen(options.pid_file, "wb");
882 fprintf(f, "%u\n", (u_int) getpid());
886 if (options.protocol & SSH_PROTO_1)
887 generate_empheral_server_key();
889 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
890 signal(SIGHUP, sighup_handler);
892 signal(SIGTERM, sigterm_handler);
893 signal(SIGQUIT, sigterm_handler);
895 /* Arrange SIGCHLD to be caught. */
896 signal(SIGCHLD, main_sigchld_handler);
898 /* setup fd set for listen */
901 for (i = 0; i < num_listen_socks; i++)
902 if (listen_socks[i] > maxfd)
903 maxfd = listen_socks[i];
904 /* pipes connected to unauthenticated childs */
905 startup_pipes = xmalloc(options.max_startups * sizeof(int));
906 for (i = 0; i < options.max_startups; i++)
907 startup_pipes[i] = -1;
910 * Stay listening for connections until the system crashes or
911 * the daemon is killed with a signal.
918 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
919 fdset = (fd_set *)xmalloc(fdsetsz);
920 memset(fdset, 0, fdsetsz);
922 for (i = 0; i < num_listen_socks; i++)
923 FD_SET(listen_socks[i], fdset);
924 for (i = 0; i < options.max_startups; i++)
925 if (startup_pipes[i] != -1)
926 FD_SET(startup_pipes[i], fdset);
928 /* Wait in select until there is a connection. */
929 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
930 if (ret < 0 && errno != EINTR)
931 error("select: %.100s", strerror(errno));
932 if (key_used && key_do_regen) {
933 generate_empheral_server_key();
940 for (i = 0; i < options.max_startups; i++)
941 if (startup_pipes[i] != -1 &&
942 FD_ISSET(startup_pipes[i], fdset)) {
944 * the read end of the pipe is ready
945 * if the child has closed the pipe
946 * after successful authentication
947 * or if the child has died
949 close(startup_pipes[i]);
950 startup_pipes[i] = -1;
953 for (i = 0; i < num_listen_socks; i++) {
954 if (!FD_ISSET(listen_socks[i], fdset))
956 fromlen = sizeof(from);
957 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
960 if (errno != EINTR && errno != EWOULDBLOCK)
961 error("accept: %.100s", strerror(errno));
964 if (fcntl(newsock, F_SETFL, 0) < 0) {
965 error("newsock del O_NONBLOCK: %s", strerror(errno));
968 if (drop_connection(startups) == 1) {
969 debug("drop connection #%d", startups);
973 if (pipe(startup_p) == -1) {
978 for (j = 0; j < options.max_startups; j++)
979 if (startup_pipes[j] == -1) {
980 startup_pipes[j] = startup_p[0];
981 if (maxfd < startup_p[0])
982 maxfd = startup_p[0];
988 * Got connection. Fork a child to handle it, unless
989 * we are in debugging mode.
993 * In debugging mode. Close the listening
994 * socket, and start processing the
995 * connection without forking.
997 debug("Server will not fork when running in debugging mode.");
998 close_listen_socks();
1006 * Normal production daemon. Fork, and have
1007 * the child process the connection. The
1008 * parent continues listening.
1010 if ((pid = fork()) == 0) {
1012 * Child. Close the listening and max_startup
1013 * sockets. Start using the accepted socket.
1014 * Reinitialize logging (since our pid has
1015 * changed). We break out of the loop to handle
1018 startup_pipe = startup_p[1];
1019 for (j = 0; j < options.max_startups; j++)
1020 if (startup_pipes[j] != -1)
1021 close(startup_pipes[j]);
1022 close_listen_socks();
1025 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1030 /* Parent. Stay in the loop. */
1032 error("fork: %.100s", strerror(errno));
1034 debug("Forked child %d.", pid);
1036 close(startup_p[1]);
1038 /* Mark that the key has been used (it was "given" to the child). */
1039 if ((options.protocol & SSH_PROTO_1) &&
1041 /* Schedule server key regeneration alarm. */
1042 signal(SIGALRM, key_regeneration_alarm);
1043 alarm(options.key_regeneration_time);
1049 /* Close the new socket (the child is now taking care of it). */
1052 /* child process check (or debug mode) */
1053 if (num_listen_socks < 0)
1058 /* This is the child processing a new connection. */
1061 * Disable the key regeneration alarm. We will not regenerate the
1062 * key since we are no longer in a position to give it to anyone. We
1063 * will not restart on SIGHUP since it no longer makes sense.
1066 signal(SIGALRM, SIG_DFL);
1067 signal(SIGHUP, SIG_DFL);
1068 signal(SIGTERM, SIG_DFL);
1069 signal(SIGQUIT, SIG_DFL);
1070 signal(SIGCHLD, SIG_DFL);
1071 signal(SIGINT, SIG_DFL);
1074 * Set socket options for the connection. We want the socket to
1075 * close as fast as possible without waiting for anything. If the
1076 * connection is not a socket, these will do nothing.
1078 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1080 linger.l_linger = 5;
1081 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1083 /* Set keepalives if requested. */
1084 if (options.keepalives &&
1085 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1087 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1090 * Register our connection. This turns encryption off because we do
1093 packet_set_connection(sock_in, sock_out);
1095 remote_port = get_remote_port();
1096 remote_ip = get_remote_ipaddr();
1098 /* Check whether logins are denied from this host. */
1100 /* XXX LIBWRAP noes not know about IPv6 */
1102 struct request_info req;
1104 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1107 if (!hosts_access(&req)) {
1112 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1114 #endif /* LIBWRAP */
1115 /* Log the connection. */
1116 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1119 * We don\'t want to listen forever unless the other side
1120 * successfully authenticates itself. So we set up an alarm which is
1121 * cleared after successful authentication. A limit of zero
1122 * indicates no limit. Note that we don\'t set the alarm in debugging
1123 * mode; it is just annoying to have the server exit just when you
1124 * are about to discover the bug.
1126 signal(SIGALRM, grace_alarm_handler);
1128 alarm(options.login_grace_time);
1130 sshd_exchange_identification(sock_in, sock_out);
1132 * Check that the connection comes from a privileged port.
1133 * Rhosts-Authentication only makes sense from priviledged
1134 * programs. Of course, if the intruder has root access on his local
1135 * machine, he can connect from any port. So do not use these
1136 * authentication methods from machines that you do not trust.
1138 if (remote_port >= IPPORT_RESERVED ||
1139 remote_port < IPPORT_RESERVED / 2) {
1140 debug("Rhosts Authentication disabled, "
1141 "originating port not trusted.");
1142 options.rhosts_authentication = 0;
1145 if (!packet_connection_is_ipv4() &&
1146 options.kerberos_authentication) {
1147 debug("Kerberos Authentication disabled, only available for IPv4.");
1148 options.kerberos_authentication = 0;
1152 packet_set_nonblocking();
1154 /* perform the key exchange */
1155 /* authenticate user and start session */
1158 do_authentication2();
1161 do_authentication();
1165 /* Cleanup user's ticket cache file. */
1166 if (options.kerberos_ticket_cleanup)
1170 /* The connection has been terminated. */
1171 verbose("Closing connection to %.100s", remote_ip);
1175 #endif /* USE_PAM */
1190 BIGNUM *session_key_int;
1191 u_char session_key[SSH_SESSION_KEY_LENGTH];
1193 u_int cipher_type, auth_mask, protocol_flags;
1197 * Generate check bytes that the client must send back in the user
1198 * packet in order for it to be accepted; this is used to defy ip
1199 * spoofing attacks. Note that this only works against somebody
1200 * doing IP spoofing from a remote machine; any machine on the local
1201 * network can still see outgoing packets and catch the random
1202 * cookie. This only affects rhosts authentication, and this is one
1203 * of the reasons why it is inherently insecure.
1205 for (i = 0; i < 8; i++) {
1207 rand = arc4random();
1208 cookie[i] = rand & 0xff;
1213 * Send our public key. We include in the packet 64 bits of random
1214 * data that must be matched in the reply in order to prevent IP
1217 packet_start(SSH_SMSG_PUBLIC_KEY);
1218 for (i = 0; i < 8; i++)
1219 packet_put_char(cookie[i]);
1221 /* Store our public server RSA key. */
1222 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1223 packet_put_bignum(sensitive_data.server_key->rsa->e);
1224 packet_put_bignum(sensitive_data.server_key->rsa->n);
1226 /* Store our public host RSA key. */
1227 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1228 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1229 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1231 /* Put protocol flags. */
1232 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1234 /* Declare which ciphers we support. */
1235 packet_put_int(cipher_mask_ssh1(0));
1237 /* Declare supported authentication types. */
1239 if (options.rhosts_authentication)
1240 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1241 if (options.rhosts_rsa_authentication)
1242 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1243 if (options.rsa_authentication)
1244 auth_mask |= 1 << SSH_AUTH_RSA;
1246 if (options.kerberos_authentication)
1247 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1250 if (options.kerberos_tgt_passing)
1251 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1252 if (options.afs_token_passing)
1253 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1255 if (options.challenge_reponse_authentication == 1)
1256 auth_mask |= 1 << SSH_AUTH_TIS;
1257 if (options.password_authentication)
1258 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1259 packet_put_int(auth_mask);
1261 /* Send the packet and wait for it to be sent. */
1263 packet_write_wait();
1265 debug("Sent %d bit server key and %d bit host key.",
1266 BN_num_bits(sensitive_data.server_key->rsa->n),
1267 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1269 /* Read clients reply (cipher type and session key). */
1270 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1272 /* Get cipher type and check whether we accept this. */
1273 cipher_type = packet_get_char();
1275 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1276 packet_disconnect("Warning: client selects unsupported cipher.");
1278 /* Get check bytes from the packet. These must match those we
1279 sent earlier with the public key packet. */
1280 for (i = 0; i < 8; i++)
1281 if (cookie[i] != packet_get_char())
1282 packet_disconnect("IP Spoofing check bytes do not match.");
1284 debug("Encryption type: %.200s", cipher_name(cipher_type));
1286 /* Get the encrypted integer. */
1287 session_key_int = BN_new();
1288 packet_get_bignum(session_key_int, &slen);
1290 protocol_flags = packet_get_int();
1291 packet_set_protocol_flags(protocol_flags);
1293 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1296 * Decrypt it using our private server key and private host key (key
1297 * with larger modulus first).
1299 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1300 /* Server key has bigger modulus. */
1301 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1302 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1303 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1304 get_remote_ipaddr(),
1305 BN_num_bits(sensitive_data.server_key->rsa->n),
1306 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1307 SSH_KEY_BITS_RESERVED);
1309 if (rsa_private_decrypt(session_key_int, session_key_int,
1310 sensitive_data.server_key->rsa) <= 0)
1312 if (rsa_private_decrypt(session_key_int, session_key_int,
1313 sensitive_data.ssh1_host_key->rsa) <= 0)
1316 /* Host key has bigger modulus (or they are equal). */
1317 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1318 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1319 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1320 get_remote_ipaddr(),
1321 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1322 BN_num_bits(sensitive_data.server_key->rsa->n),
1323 SSH_KEY_BITS_RESERVED);
1325 if (rsa_private_decrypt(session_key_int, session_key_int,
1326 sensitive_data.ssh1_host_key->rsa) < 0)
1328 if (rsa_private_decrypt(session_key_int, session_key_int,
1329 sensitive_data.server_key->rsa) < 0)
1333 compute_session_id(session_id, cookie,
1334 sensitive_data.ssh1_host_key->rsa->n,
1335 sensitive_data.server_key->rsa->n);
1337 /* Destroy the private and public keys. They will no longer be needed. */
1338 destroy_sensitive_data();
1341 * Extract session key from the decrypted integer. The key is in the
1342 * least significant 256 bits of the integer; the first byte of the
1343 * key is in the highest bits.
1346 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1347 len = BN_num_bytes(session_key_int);
1348 if (len < 0 || len > sizeof(session_key)) {
1349 error("do_connection: bad session key len from %s: "
1350 "session_key_int %d > sizeof(session_key) %d",
1351 get_remote_ipaddr(), len, (int)sizeof(session_key));
1354 memset(session_key, 0, sizeof(session_key));
1355 BN_bn2bin(session_key_int,
1356 session_key + sizeof(session_key) - len);
1360 log("do_connection: generating a fake encryption key");
1361 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1363 rand = arc4random();
1364 session_key[i] = rand & 0xff;
1368 /* Destroy the decrypted integer. It is no longer needed. */
1369 BN_clear_free(session_key_int);
1371 /* Xor the first 16 bytes of the session key with the session id. */
1372 for (i = 0; i < 16; i++)
1373 session_key[i] ^= session_id[i];
1375 /* Set the session key. From this on all communications will be encrypted. */
1376 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1378 /* Destroy our copy of the session key. It is no longer needed. */
1379 memset(session_key, 0, sizeof(session_key));
1381 debug("Received session key; encryption turned on.");
1383 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1384 packet_start(SSH_SMSG_SUCCESS);
1386 packet_write_wait();
1390 * SSH2 key exchange: diffie-hellman-group1-sha1
1395 Buffer *server_kexinit;
1396 Buffer *client_kexinit;
1400 char *cprop[PROPOSAL_MAX];
1404 if (options.ciphers != NULL) {
1405 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1406 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1408 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1410 server_kexinit = kex_init(myproposal);
1411 client_kexinit = xmalloc(sizeof(*client_kexinit));
1412 buffer_init(client_kexinit);
1414 /* algorithm negotiation */
1415 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1416 kex = kex_choose_conf(cprop, myproposal, 1);
1417 for (i = 0; i < PROPOSAL_MAX; i++)
1420 switch (kex->kex_type) {
1422 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1425 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1428 fatal("Unsupported key exchange %d", kex->kex_type);
1431 debug("send SSH2_MSG_NEWKEYS.");
1432 packet_start(SSH2_MSG_NEWKEYS);
1434 packet_write_wait();
1435 debug("done: send SSH2_MSG_NEWKEYS.");
1437 debug("Wait SSH2_MSG_NEWKEYS.");
1438 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1439 debug("GOT SSH2_MSG_NEWKEYS.");
1442 /* send 1st encrypted/maced/compressed message */
1443 packet_start(SSH2_MSG_IGNORE);
1444 packet_put_cstring("markus");
1446 packet_write_wait();
1449 debug("done: KEX2.");
1456 /* diffie-hellman-group1-sha1 */
1459 ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1464 int payload_len, dlen;
1466 u_char *signature = NULL;
1467 u_char *server_host_key_blob = NULL;
1472 BIGNUM *shared_secret = 0;
1474 BIGNUM *dh_client_pub = 0;
1477 hostkey = get_hostkey_by_type(kex->hostkey_type);
1478 if (hostkey == NULL)
1479 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1482 /* generate DH key */
1483 dh = dh_new_group1(); /* XXX depends on 'kex' */
1486 debug("Wait SSH2_MSG_KEXDH_INIT.");
1487 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1490 dh_client_pub = BN_new();
1491 if (dh_client_pub == NULL)
1492 fatal("dh_client_pub == NULL");
1493 packet_get_bignum2(dh_client_pub, &dlen);
1496 fprintf(stderr, "\ndh_client_pub= ");
1497 BN_print_fp(stderr, dh_client_pub);
1498 fprintf(stderr, "\n");
1499 debug("bits %d", BN_num_bits(dh_client_pub));
1503 fprintf(stderr, "\np= ");
1504 BN_print_fp(stderr, dh->p);
1505 fprintf(stderr, "\ng= ");
1507 fprintf(stderr, "\npub= ");
1508 BN_print_fp(stderr, dh->pub_key);
1509 fprintf(stderr, "\n");
1510 DHparams_print_fp(stderr, dh);
1512 if (!dh_pub_is_valid(dh, dh_client_pub))
1513 packet_disconnect("bad client public DH value");
1516 kbuf = xmalloc(klen);
1517 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1520 debug("shared secret: len %d/%d", klen, kout);
1521 fprintf(stderr, "shared secret == ");
1522 for (i = 0; i< kout; i++)
1523 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1524 fprintf(stderr, "\n");
1526 shared_secret = BN_new();
1528 BN_bin2bn(kbuf, kout, shared_secret);
1529 memset(kbuf, 0, klen);
1532 /* XXX precompute? */
1533 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1535 /* calc H */ /* XXX depends on 'kex' */
1537 client_version_string,
1538 server_version_string,
1539 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1540 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1541 (char *)server_host_key_blob, sbloblen,
1546 buffer_free(client_kexinit);
1547 buffer_free(server_kexinit);
1548 xfree(client_kexinit);
1549 xfree(server_kexinit);
1550 BN_free(dh_client_pub);
1552 fprintf(stderr, "hash == ");
1553 for (i = 0; i< 20; i++)
1554 fprintf(stderr, "%02x", (hash[i])&0xff);
1555 fprintf(stderr, "\n");
1557 /* save session id := H */
1558 /* XXX hashlen depends on KEX */
1559 session_id2_len = 20;
1560 session_id2 = xmalloc(session_id2_len);
1561 memcpy(session_id2, hash, session_id2_len);
1564 /* XXX hashlen depends on KEX */
1565 key_sign(hostkey, &signature, &slen, hash, 20);
1567 destroy_sensitive_data();
1569 /* send server hostkey, DH pubkey 'f' and singed H */
1570 packet_start(SSH2_MSG_KEXDH_REPLY);
1571 packet_put_string((char *)server_host_key_blob, sbloblen);
1572 packet_put_bignum2(dh->pub_key); /* f */
1573 packet_put_string((char *)signature, slen);
1576 xfree(server_host_key_blob);
1577 packet_write_wait();
1579 kex_derive_keys(kex, hash, shared_secret);
1580 BN_clear_free(shared_secret);
1581 packet_set_kex(kex);
1583 /* have keys, free DH */
1587 /* diffie-hellman-group-exchange-sha1 */
1590 ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1595 int payload_len, dlen;
1597 u_char *signature = NULL;
1598 u_char *server_host_key_blob = NULL;
1603 BIGNUM *shared_secret = 0;
1605 BIGNUM *dh_client_pub = 0;
1608 hostkey = get_hostkey_by_type(kex->hostkey_type);
1609 if (hostkey == NULL)
1610 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1613 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1614 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1615 nbits = packet_get_int();
1616 dh = choose_dh(nbits);
1618 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1619 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1620 packet_put_bignum2(dh->p);
1621 packet_put_bignum2(dh->g);
1623 packet_write_wait();
1625 /* Compute our exchange value in parallel with the client */
1629 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1630 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1633 dh_client_pub = BN_new();
1634 if (dh_client_pub == NULL)
1635 fatal("dh_client_pub == NULL");
1636 packet_get_bignum2(dh_client_pub, &dlen);
1639 fprintf(stderr, "\ndh_client_pub= ");
1640 BN_print_fp(stderr, dh_client_pub);
1641 fprintf(stderr, "\n");
1642 debug("bits %d", BN_num_bits(dh_client_pub));
1646 fprintf(stderr, "\np= ");
1647 BN_print_fp(stderr, dh->p);
1648 fprintf(stderr, "\ng= ");
1650 fprintf(stderr, "\npub= ");
1651 BN_print_fp(stderr, dh->pub_key);
1652 fprintf(stderr, "\n");
1653 DHparams_print_fp(stderr, dh);
1655 if (!dh_pub_is_valid(dh, dh_client_pub))
1656 packet_disconnect("bad client public DH value");
1659 kbuf = xmalloc(klen);
1660 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1663 debug("shared secret: len %d/%d", klen, kout);
1664 fprintf(stderr, "shared secret == ");
1665 for (i = 0; i< kout; i++)
1666 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1667 fprintf(stderr, "\n");
1669 shared_secret = BN_new();
1671 BN_bin2bn(kbuf, kout, shared_secret);
1672 memset(kbuf, 0, klen);
1675 /* XXX precompute? */
1676 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1678 /* calc H */ /* XXX depends on 'kex' */
1679 hash = kex_hash_gex(
1680 client_version_string,
1681 server_version_string,
1682 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1683 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1684 (char *)server_host_key_blob, sbloblen,
1685 nbits, dh->p, dh->g,
1690 buffer_free(client_kexinit);
1691 buffer_free(server_kexinit);
1692 xfree(client_kexinit);
1693 xfree(server_kexinit);
1694 BN_free(dh_client_pub);
1696 fprintf(stderr, "hash == ");
1697 for (i = 0; i< 20; i++)
1698 fprintf(stderr, "%02x", (hash[i])&0xff);
1699 fprintf(stderr, "\n");
1701 /* save session id := H */
1702 /* XXX hashlen depends on KEX */
1703 session_id2_len = 20;
1704 session_id2 = xmalloc(session_id2_len);
1705 memcpy(session_id2, hash, session_id2_len);
1708 /* XXX hashlen depends on KEX */
1709 key_sign(hostkey, &signature, &slen, hash, 20);
1711 destroy_sensitive_data();
1713 /* send server hostkey, DH pubkey 'f' and singed H */
1714 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1715 packet_put_string((char *)server_host_key_blob, sbloblen);
1716 packet_put_bignum2(dh->pub_key); /* f */
1717 packet_put_string((char *)signature, slen);
1720 xfree(server_host_key_blob);
1721 packet_write_wait();
1723 kex_derive_keys(kex, hash, shared_secret);
1724 BN_clear_free(shared_secret);
1725 packet_set_kex(kex);
1727 /* have keys, free DH */