/* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * This program is the ssh daemon. It listens for connections from clients, * and performs authentication, executes use commands or shell, and forwards * information to/from the application to the user client over an encrypted * connection. This can also handle forwarding of X11, TCP/IP, and * authentication agent connections. * * As far as I am concerned, the code I have written for this software * can be used freely for any purpose. Any derived versions of this * software must be clearly marked as such, and if the derived work is * incompatible with the protocol description in the RFC file, it must be * called by a name other than "ssh" or "Secure Shell". * * SSH2 implementation: * Privilege Separation: * * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. * Copyright (c) 2002 Niels Provos. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" RCSID("$OpenBSD: sshd.c,v 1.262 2003/01/27 17:06:31 markus Exp $"); #include #include #include #include #include "ssh.h" #include "ssh1.h" #include "ssh2.h" #include "xmalloc.h" #include "rsa.h" #include "sshpty.h" #include "packet.h" #include "mpaux.h" #include "log.h" #include "servconf.h" #include "uidswap.h" #include "compat.h" #include "buffer.h" #include "cipher.h" #include "kex.h" #include "key.h" #include "dh.h" #include "myproposal.h" #include "authfile.h" #include "pathnames.h" #include "atomicio.h" #include "canohost.h" #include "auth.h" #include "misc.h" #include "dispatch.h" #include "channels.h" #include "session.h" #include "monitor_mm.h" #include "monitor.h" #include "monitor_wrap.h" #include "monitor_fdpass.h" #ifdef LIBWRAP #include #include int allow_severity = LOG_INFO; int deny_severity = LOG_WARNING; #endif /* LIBWRAP */ #ifndef O_NOCTTY #define O_NOCTTY 0 #endif extern char *__progname; /* Server configuration options. */ ServerOptions options; /* Name of the server configuration file. */ char *config_file_name = _PATH_SERVER_CONFIG_FILE; /* * Flag indicating whether IPv4 or IPv6. This can be set on the command line. * Default value is AF_UNSPEC means both IPv4 and IPv6. */ int IPv4or6 = AF_UNSPEC; /* * Debug mode flag. This can be set on the command line. If debug * mode is enabled, extra debugging output will be sent to the system * log, the daemon will not go to background, and will exit after processing * the first connection. */ int debug_flag = 0; /* Flag indicating that the daemon should only test the configuration and keys. */ int test_flag = 0; /* Flag indicating that the daemon is being started from inetd. */ int inetd_flag = 0; /* Flag indicating that sshd should not detach and become a daemon. */ int no_daemon_flag = 0; /* debug goes to stderr unless inetd_flag is set */ int log_stderr = 0; /* Saved arguments to main(). */ char **saved_argv; /* * The sockets that the server is listening; this is used in the SIGHUP * signal handler. */ #define MAX_LISTEN_SOCKS 16 int listen_socks[MAX_LISTEN_SOCKS]; int num_listen_socks = 0; /* * the client's version string, passed by sshd2 in compat mode. if != NULL, * sshd will skip the version-number exchange */ char *client_version_string = NULL; char *server_version_string = NULL; /* for rekeying XXX fixme */ Kex *xxx_kex; /* * Any really sensitive data in the application is contained in this * structure. The idea is that this structure could be locked into memory so * that the pages do not get written into swap. However, there are some * problems. The private key contains BIGNUMs, and we do not (in principle) * have access to the internals of them, and locking just the structure is * not very useful. Currently, memory locking is not implemented. */ struct { Key *server_key; /* ephemeral server key */ Key *ssh1_host_key; /* ssh1 host key */ Key **host_keys; /* all private host keys */ int have_ssh1_key; int have_ssh2_key; u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; } sensitive_data; /* * Flag indicating whether the RSA server key needs to be regenerated. * Is set in the SIGALRM handler and cleared when the key is regenerated. */ static volatile sig_atomic_t key_do_regen = 0; /* This is set to true when a signal is received. */ static volatile sig_atomic_t received_sighup = 0; static volatile sig_atomic_t received_sigterm = 0; /* session identifier, used by RSA-auth */ u_char session_id[16]; /* same for ssh2 */ u_char *session_id2 = NULL; int session_id2_len = 0; /* record remote hostname or ip */ u_int utmp_len = MAXHOSTNAMELEN; /* options.max_startup sized array of fd ints */ int *startup_pipes = NULL; int startup_pipe; /* in child */ /* variables used for privilege separation */ extern struct monitor *pmonitor; extern int use_privsep; /* Prototypes for various functions defined later in this file. */ void destroy_sensitive_data(void); void demote_sensitive_data(void); static void do_ssh1_kex(void); static void do_ssh2_kex(void); /* * Close all listening sockets */ static void close_listen_socks(void) { int i; for (i = 0; i < num_listen_socks; i++) close(listen_socks[i]); num_listen_socks = -1; } static void close_startup_pipes(void) { int i; if (startup_pipes) for (i = 0; i < options.max_startups; i++) if (startup_pipes[i] != -1) close(startup_pipes[i]); } /* * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; * the effect is to reread the configuration file (and to regenerate * the server key). */ static void sighup_handler(int sig) { int save_errno = errno; received_sighup = 1; signal(SIGHUP, sighup_handler); errno = save_errno; } /* * Called from the main program after receiving SIGHUP. * Restarts the server. */ static void sighup_restart(void) { log("Received SIGHUP; restarting."); close_listen_socks(); close_startup_pipes(); execv(saved_argv[0], saved_argv); log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno)); exit(1); } /* * Generic signal handler for terminating signals in the master daemon. */ static void sigterm_handler(int sig) { received_sigterm = sig; } /* * SIGCHLD handler. This is called whenever a child dies. This will then * reap any zombies left by exited children. */ static void main_sigchld_handler(int sig) { int save_errno = errno; pid_t pid; int status; while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || (pid < 0 && errno == EINTR)) ; signal(SIGCHLD, main_sigchld_handler); errno = save_errno; } /* * Signal handler for the alarm after the login grace period has expired. */ static void grace_alarm_handler(int sig) { /* XXX no idea how fix this signal handler */ /* Log error and exit. */ fatal("Timeout before authentication for %s", get_remote_ipaddr()); } /* * Signal handler for the key regeneration alarm. Note that this * alarm only occurs in the daemon waiting for connections, and it does not * do anything with the private key or random state before forking. * Thus there should be no concurrency control/asynchronous execution * problems. */ static void generate_ephemeral_server_key(void) { u_int32_t rnd = 0; int i; verbose("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "", options.server_key_bits); if (sensitive_data.server_key != NULL) key_free(sensitive_data.server_key); sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits); verbose("RSA key generation complete."); for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { if (i % 4 == 0) rnd = arc4random(); sensitive_data.ssh1_cookie[i] = rnd & 0xff; rnd >>= 8; } arc4random_stir(); } static void key_regeneration_alarm(int sig) { int save_errno = errno; signal(SIGALRM, SIG_DFL); errno = save_errno; key_do_regen = 1; } static void sshd_exchange_identification(int sock_in, int sock_out) { int i, mismatch; int remote_major, remote_minor; int major, minor; char *s; char buf[256]; /* Must not be larger than remote_version. */ char remote_version[256]; /* Must be at least as big as buf. */ if ((options.protocol & SSH_PROTO_1) && (options.protocol & SSH_PROTO_2)) { major = PROTOCOL_MAJOR_1; minor = 99; } else if (options.protocol & SSH_PROTO_2) { major = PROTOCOL_MAJOR_2; minor = PROTOCOL_MINOR_2; } else { major = PROTOCOL_MAJOR_1; minor = PROTOCOL_MINOR_1; } snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); server_version_string = xstrdup(buf); if (client_version_string == NULL) { /* Send our protocol version identification. */ if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) != strlen(server_version_string)) { log("Could not write ident string to %s", get_remote_ipaddr()); fatal_cleanup(); } /* Read other sides version identification. */ memset(buf, 0, sizeof(buf)); for (i = 0; i < sizeof(buf) - 1; i++) { if (atomicio(read, sock_in, &buf[i], 1) != 1) { log("Did not receive identification string from %s", get_remote_ipaddr()); fatal_cleanup(); } if (buf[i] == '\r') { buf[i] = 0; /* Kludge for F-Secure Macintosh < 1.0.2 */ if (i == 12 && strncmp(buf, "SSH-1.5-W1.0", 12) == 0) break; continue; } if (buf[i] == '\n') { buf[i] = 0; break; } } buf[sizeof(buf) - 1] = 0; client_version_string = xstrdup(buf); } /* * Check that the versions match. In future this might accept * several versions and set appropriate flags to handle them. */ if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, remote_version) != 3) { s = "Protocol mismatch.\n"; (void) atomicio(write, sock_out, s, strlen(s)); close(sock_in); close(sock_out); log("Bad protocol version identification '%.100s' from %s", client_version_string, get_remote_ipaddr()); fatal_cleanup(); } debug("Client protocol version %d.%d; client software version %.100s", remote_major, remote_minor, remote_version); compat_datafellows(remote_version); if (datafellows & SSH_BUG_PROBE) { log("probed from %s with %s. Don't panic.", get_remote_ipaddr(), client_version_string); fatal_cleanup(); } if (datafellows & SSH_BUG_SCANNER) { log("scanned from %s with %s. Don't panic.", get_remote_ipaddr(), client_version_string); fatal_cleanup(); } mismatch = 0; switch (remote_major) { case 1: if (remote_minor == 99) { if (options.protocol & SSH_PROTO_2) enable_compat20(); else mismatch = 1; break; } if (!(options.protocol & SSH_PROTO_1)) { mismatch = 1; break; } if (remote_minor < 3) { packet_disconnect("Your ssh version is too old and " "is no longer supported. Please install a newer version."); } else if (remote_minor == 3) { /* note that this disables agent-forwarding */ enable_compat13(); } break; case 2: if (options.protocol & SSH_PROTO_2) { enable_compat20(); break; } /* FALLTHROUGH */ default: mismatch = 1; break; } chop(server_version_string); debug("Local version string %.200s", server_version_string); if (mismatch) { s = "Protocol major versions differ.\n"; (void) atomicio(write, sock_out, s, strlen(s)); close(sock_in); close(sock_out); log("Protocol major versions differ for %s: %.200s vs. %.200s", get_remote_ipaddr(), server_version_string, client_version_string); fatal_cleanup(); } } /* Destroy the host and server keys. They will no longer be needed. */ void destroy_sensitive_data(void) { int i; if (sensitive_data.server_key) { key_free(sensitive_data.server_key); sensitive_data.server_key = NULL; } for (i = 0; i < options.num_host_key_files; i++) { if (sensitive_data.host_keys[i]) { key_free(sensitive_data.host_keys[i]); sensitive_data.host_keys[i] = NULL; } } sensitive_data.ssh1_host_key = NULL; memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); } /* Demote private to public keys for network child */ void demote_sensitive_data(void) { Key *tmp; int i; if (sensitive_data.server_key) { tmp = key_demote(sensitive_data.server_key); key_free(sensitive_data.server_key); sensitive_data.server_key = tmp; } for (i = 0; i < options.num_host_key_files; i++) { if (sensitive_data.host_keys[i]) { tmp = key_demote(sensitive_data.host_keys[i]); key_free(sensitive_data.host_keys[i]); sensitive_data.host_keys[i] = tmp; if (tmp->type == KEY_RSA1) sensitive_data.ssh1_host_key = tmp; } } /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ } static void privsep_preauth_child(void) { u_int32_t rnd[256]; gid_t gidset[1]; struct passwd *pw; int i; /* Enable challenge-response authentication for privilege separation */ privsep_challenge_enable(); for (i = 0; i < 256; i++) rnd[i] = arc4random(); RAND_seed(rnd, sizeof(rnd)); /* Demote the private keys to public keys. */ demote_sensitive_data(); if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) fatal("Privilege separation user %s does not exist", SSH_PRIVSEP_USER); memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); endpwent(); /* Change our root directory */ if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, strerror(errno)); if (chdir("/") == -1) fatal("chdir(\"/\"): %s", strerror(errno)); /* Drop our privileges */ debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, (u_int)pw->pw_gid); #if 0 /* XXX not ready, to heavy after chroot */ do_setusercontext(pw); #else gidset[0] = pw->pw_gid; if (setgid(pw->pw_gid) < 0) fatal("setgid failed for %u", pw->pw_gid ); if (setgroups(1, gidset) < 0) fatal("setgroups: %.100s", strerror(errno)); permanently_set_uid(pw); #endif } static Authctxt * privsep_preauth(void) { Authctxt *authctxt = NULL; int status; pid_t pid; /* Set up unprivileged child process to deal with network data */ pmonitor = monitor_init(); /* Store a pointer to the kex for later rekeying */ pmonitor->m_pkex = &xxx_kex; pid = fork(); if (pid == -1) { fatal("fork of unprivileged child failed"); } else if (pid != 0) { fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); debug2("Network child is on pid %ld", (long)pid); close(pmonitor->m_recvfd); authctxt = monitor_child_preauth(pmonitor); close(pmonitor->m_sendfd); /* Sync memory */ monitor_sync(pmonitor); /* Wait for the child's exit status */ while (waitpid(pid, &status, 0) < 0) if (errno != EINTR) break; /* Reinstall, since the child has finished */ fatal_add_cleanup((void (*) (void *)) packet_close, NULL); return (authctxt); } else { /* child */ close(pmonitor->m_sendfd); /* Demote the child */ if (getuid() == 0 || geteuid() == 0) privsep_preauth_child(); setproctitle("%s", "[net]"); } return (NULL); } static void privsep_postauth(Authctxt *authctxt) { extern Authctxt *x_authctxt; /* XXX - Remote port forwarding */ x_authctxt = authctxt; if (authctxt->pw->pw_uid == 0 || options.use_login) { /* File descriptor passing is broken or root login */ monitor_apply_keystate(pmonitor); use_privsep = 0; return; } /* Authentication complete */ alarm(0); if (startup_pipe != -1) { close(startup_pipe); startup_pipe = -1; } /* New socket pair */ monitor_reinit(pmonitor); pmonitor->m_pid = fork(); if (pmonitor->m_pid == -1) fatal("fork of unprivileged child failed"); else if (pmonitor->m_pid != 0) { fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); debug2("User child is on pid %ld", (long)pmonitor->m_pid); close(pmonitor->m_recvfd); monitor_child_postauth(pmonitor); /* NEVERREACHED */ exit(0); } close(pmonitor->m_sendfd); /* Demote the private keys to public keys. */ demote_sensitive_data(); /* Drop privileges */ do_setusercontext(authctxt->pw); /* It is safe now to apply the key state */ monitor_apply_keystate(pmonitor); } static char * list_hostkey_types(void) { Buffer b; char *p; int i; buffer_init(&b); for (i = 0; i < options.num_host_key_files; i++) { Key *key = sensitive_data.host_keys[i]; if (key == NULL) continue; switch (key->type) { case KEY_RSA: case KEY_DSA: if (buffer_len(&b) > 0) buffer_append(&b, ",", 1); p = key_ssh_name(key); buffer_append(&b, p, strlen(p)); break; } } buffer_append(&b, "\0", 1); p = xstrdup(buffer_ptr(&b)); buffer_free(&b); debug("list_hostkey_types: %s", p); return p; } Key * get_hostkey_by_type(int type) { int i; for (i = 0; i < options.num_host_key_files; i++) { Key *key = sensitive_data.host_keys[i]; if (key != NULL && key->type == type) return key; } return NULL; } Key * get_hostkey_by_index(int ind) { if (ind < 0 || ind >= options.num_host_key_files) return (NULL); return (sensitive_data.host_keys[ind]); } int get_hostkey_index(Key *key) { int i; for (i = 0; i < options.num_host_key_files; i++) { if (key == sensitive_data.host_keys[i]) return (i); } return (-1); } /* * returns 1 if connection should be dropped, 0 otherwise. * dropping starts at connection #max_startups_begin with a probability * of (max_startups_rate/100). the probability increases linearly until * all connections are dropped for startups > max_startups */ static int drop_connection(int startups) { double p, r; if (startups < options.max_startups_begin) return 0; if (startups >= options.max_startups) return 1; if (options.max_startups_rate == 100) return 1; p = 100 - options.max_startups_rate; p *= startups - options.max_startups_begin; p /= (double) (options.max_startups - options.max_startups_begin); p += options.max_startups_rate; p /= 100.0; r = arc4random() / (double) UINT_MAX; debug("drop_connection: p %g, r %g", p, r); return (r < p) ? 1 : 0; } static void usage(void) { fprintf(stderr, "sshd version %s\n", SSH_VERSION); fprintf(stderr, "Usage: %s [options]\n", __progname); fprintf(stderr, "Options:\n"); fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); fprintf(stderr, " -i Started from inetd\n"); fprintf(stderr, " -D Do not fork into daemon mode\n"); fprintf(stderr, " -t Only test configuration file and keys\n"); fprintf(stderr, " -q Quiet (no logging)\n"); fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); fprintf(stderr, " -h file File from which to read host key (default: %s)\n", _PATH_HOST_KEY_FILE); fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); fprintf(stderr, " -4 Use IPv4 only\n"); fprintf(stderr, " -6 Use IPv6 only\n"); fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); exit(1); } /* * Main program for the daemon. */ int main(int ac, char **av) { extern char *optarg; extern int optind; int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; pid_t pid; socklen_t fromlen; fd_set *fdset; struct sockaddr_storage from; const char *remote_ip; int remote_port; FILE *f; struct addrinfo *ai; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; int listen_sock, maxfd; int startup_p[2]; int startups = 0; Authctxt *authctxt; Key *key; int ret, key_used = 0; /* Save argv. */ saved_argv = av; /* Initialize configuration options to their default values. */ initialize_server_options(&options); /* Parse command-line arguments. */ while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { switch (opt) { case '4': IPv4or6 = AF_INET; break; case '6': IPv4or6 = AF_INET6; break; case 'f': config_file_name = optarg; break; case 'd': if (0 == debug_flag) { debug_flag = 1; options.log_level = SYSLOG_LEVEL_DEBUG1; } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { options.log_level++; } else { fprintf(stderr, "Too high debugging level.\n"); exit(1); } break; case 'D': no_daemon_flag = 1; break; case 'e': log_stderr = 1; break; case 'i': inetd_flag = 1; break; case 'Q': /* ignored */ break; case 'q': options.log_level = SYSLOG_LEVEL_QUIET; break; case 'b': options.server_key_bits = atoi(optarg); break; case 'p': options.ports_from_cmdline = 1; if (options.num_ports >= MAX_PORTS) { fprintf(stderr, "too many ports.\n"); exit(1); } options.ports[options.num_ports++] = a2port(optarg); if (options.ports[options.num_ports-1] == 0) { fprintf(stderr, "Bad port number.\n"); exit(1); } break; case 'g': if ((options.login_grace_time = convtime(optarg)) == -1) { fprintf(stderr, "Invalid login grace time.\n"); exit(1); } break; case 'k': if ((options.key_regeneration_time = convtime(optarg)) == -1) { fprintf(stderr, "Invalid key regeneration interval.\n"); exit(1); } break; case 'h': if (options.num_host_key_files >= MAX_HOSTKEYS) { fprintf(stderr, "too many host keys.\n"); exit(1); } options.host_key_files[options.num_host_key_files++] = optarg; break; case 'V': client_version_string = optarg; /* only makes sense with inetd_flag, i.e. no listen() */ inetd_flag = 1; break; case 't': test_flag = 1; break; case 'u': utmp_len = atoi(optarg); if (utmp_len > MAXHOSTNAMELEN) { fprintf(stderr, "Invalid utmp length.\n"); exit(1); } break; case 'o': if (process_server_config_line(&options, optarg, "command-line", 0) != 0) exit(1); break; case '?': default: usage(); break; } } SSLeay_add_all_algorithms(); channel_set_af(IPv4or6); /* * Force logging to stderr until we have loaded the private host * key (unless started from inetd) */ log_init(__progname, options.log_level == SYSLOG_LEVEL_NOT_SET ? SYSLOG_LEVEL_INFO : options.log_level, options.log_facility == SYSLOG_FACILITY_NOT_SET ? SYSLOG_FACILITY_AUTH : options.log_facility, log_stderr || !inetd_flag); /* Read server configuration options from the configuration file. */ read_server_config(&options, config_file_name); /* Fill in default values for those options not explicitly set. */ fill_default_server_options(&options); /* Check that there are no remaining arguments. */ if (optind < ac) { fprintf(stderr, "Extra argument %s.\n", av[optind]); exit(1); } debug("sshd version %.100s", SSH_VERSION); /* load private host keys */ sensitive_data.host_keys = xmalloc(options.num_host_key_files * sizeof(Key *)); for (i = 0; i < options.num_host_key_files; i++) sensitive_data.host_keys[i] = NULL; sensitive_data.server_key = NULL; sensitive_data.ssh1_host_key = NULL; sensitive_data.have_ssh1_key = 0; sensitive_data.have_ssh2_key = 0; for (i = 0; i < options.num_host_key_files; i++) { key = key_load_private(options.host_key_files[i], "", NULL); sensitive_data.host_keys[i] = key; if (key == NULL) { error("Could not load host key: %s", options.host_key_files[i]); sensitive_data.host_keys[i] = NULL; continue; } switch (key->type) { case KEY_RSA1: sensitive_data.ssh1_host_key = key; sensitive_data.have_ssh1_key = 1; break; case KEY_RSA: case KEY_DSA: sensitive_data.have_ssh2_key = 1; break; } debug("private host key: #%d type %d %s", i, key->type, key_type(key)); } if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { log("Disabling protocol version 1. Could not load host key"); options.protocol &= ~SSH_PROTO_1; } if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { log("Disabling protocol version 2. Could not load host key"); options.protocol &= ~SSH_PROTO_2; } if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { log("sshd: no hostkeys available -- exiting."); exit(1); } /* Check certain values for sanity. */ if (options.protocol & SSH_PROTO_1) { if (options.server_key_bits < 512 || options.server_key_bits > 32768) { fprintf(stderr, "Bad server key size.\n"); exit(1); } /* * Check that server and host key lengths differ sufficiently. This * is necessary to make double encryption work with rsaref. Oh, I * hate software patents. I dont know if this can go? Niels */ if (options.server_key_bits > BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && options.server_key_bits < BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { options.server_key_bits = BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; debug("Forcing server key to %d bits to make it differ from host key.", options.server_key_bits); } } if (use_privsep) { struct passwd *pw; struct stat st; if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) fatal("Privilege separation user %s does not exist", SSH_PRIVSEP_USER); if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || (S_ISDIR(st.st_mode) == 0)) fatal("Missing privilege separation directory: %s", _PATH_PRIVSEP_CHROOT_DIR); if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) fatal("%s must be owned by root and not group or " "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); } /* Configuration looks good, so exit if in test mode. */ if (test_flag) exit(0); /* Initialize the log (it is reinitialized below in case we forked). */ if (debug_flag && !inetd_flag) log_stderr = 1; log_init(__progname, options.log_level, options.log_facility, log_stderr); /* * If not in debugging mode, and not started from inetd, disconnect * from the controlling terminal, and fork. The original process * exits. */ if (!(debug_flag || inetd_flag || no_daemon_flag)) { #ifdef TIOCNOTTY int fd; #endif /* TIOCNOTTY */ if (daemon(0, 0) < 0) fatal("daemon() failed: %.200s", strerror(errno)); /* Disconnect from the controlling tty. */ #ifdef TIOCNOTTY fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); if (fd >= 0) { (void) ioctl(fd, TIOCNOTTY, NULL); close(fd); } #endif /* TIOCNOTTY */ } /* Reinitialize the log (because of the fork above). */ log_init(__progname, options.log_level, options.log_facility, log_stderr); /* Initialize the random number generator. */ arc4random_stir(); /* Chdir to the root directory so that the current disk can be unmounted if desired. */ chdir("/"); /* ignore SIGPIPE */ signal(SIGPIPE, SIG_IGN); /* Start listening for a socket, unless started from inetd. */ if (inetd_flag) { int s1; s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ dup(s1); sock_in = dup(0); sock_out = dup(1); startup_pipe = -1; /* * We intentionally do not close the descriptors 0, 1, and 2 * as our code for setting the descriptors won\'t work if * ttyfd happens to be one of those. */ debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); if (options.protocol & SSH_PROTO_1) generate_ephemeral_server_key(); } else { for (ai = options.listen_addrs; ai; ai = ai->ai_next) { if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) continue; if (num_listen_socks >= MAX_LISTEN_SOCKS) fatal("Too many listen sockets. " "Enlarge MAX_LISTEN_SOCKS"); if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) { error("getnameinfo failed"); continue; } /* Create socket for listening. */ listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); if (listen_sock < 0) { /* kernel may not support ipv6 */ verbose("socket: %.100s", strerror(errno)); continue; } if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { error("listen_sock O_NONBLOCK: %s", strerror(errno)); close(listen_sock); continue; } /* * Set socket options. * Allow local port reuse in TIME_WAIT. */ if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) error("setsockopt SO_REUSEADDR: %s", strerror(errno)); debug("Bind to port %s on %s.", strport, ntop); /* Bind the socket to the desired port. */ if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { error("Bind to port %s on %s failed: %.200s.", strport, ntop, strerror(errno)); close(listen_sock); continue; } listen_socks[num_listen_socks] = listen_sock; num_listen_socks++; /* Start listening on the port. */ log("Server listening on %s port %s.", ntop, strport); if (listen(listen_sock, 5) < 0) fatal("listen: %.100s", strerror(errno)); } freeaddrinfo(options.listen_addrs); if (!num_listen_socks) fatal("Cannot bind any address."); if (options.protocol & SSH_PROTO_1) generate_ephemeral_server_key(); /* * Arrange to restart on SIGHUP. The handler needs * listen_sock. */ signal(SIGHUP, sighup_handler); signal(SIGTERM, sigterm_handler); signal(SIGQUIT, sigterm_handler); /* Arrange SIGCHLD to be caught. */ signal(SIGCHLD, main_sigchld_handler); /* Write out the pid file after the sigterm handler is setup */ if (!debug_flag) { /* * Record our pid in /var/run/sshd.pid to make it * easier to kill the correct sshd. We don't want to * do this before the bind above because the bind will * fail if there already is a daemon, and this will * overwrite any old pid in the file. */ f = fopen(options.pid_file, "w"); if (f) { fprintf(f, "%ld\n", (long) getpid()); fclose(f); } } /* setup fd set for listen */ fdset = NULL; maxfd = 0; for (i = 0; i < num_listen_socks; i++) if (listen_socks[i] > maxfd) maxfd = listen_socks[i]; /* pipes connected to unauthenticated childs */ startup_pipes = xmalloc(options.max_startups * sizeof(int)); for (i = 0; i < options.max_startups; i++) startup_pipes[i] = -1; /* * Stay listening for connections until the system crashes or * the daemon is killed with a signal. */ for (;;) { if (received_sighup) sighup_restart(); if (fdset != NULL) xfree(fdset); fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); fdset = (fd_set *)xmalloc(fdsetsz); memset(fdset, 0, fdsetsz); for (i = 0; i < num_listen_socks; i++) FD_SET(listen_socks[i], fdset); for (i = 0; i < options.max_startups; i++) if (startup_pipes[i] != -1) FD_SET(startup_pipes[i], fdset); /* Wait in select until there is a connection. */ ret = select(maxfd+1, fdset, NULL, NULL, NULL); if (ret < 0 && errno != EINTR) error("select: %.100s", strerror(errno)); if (received_sigterm) { log("Received signal %d; terminating.", (int) received_sigterm); close_listen_socks(); unlink(options.pid_file); exit(255); } if (key_used && key_do_regen) { generate_ephemeral_server_key(); key_used = 0; key_do_regen = 0; } if (ret < 0) continue; for (i = 0; i < options.max_startups; i++) if (startup_pipes[i] != -1 && FD_ISSET(startup_pipes[i], fdset)) { /* * the read end of the pipe is ready * if the child has closed the pipe * after successful authentication * or if the child has died */ close(startup_pipes[i]); startup_pipes[i] = -1; startups--; } for (i = 0; i < num_listen_socks; i++) { if (!FD_ISSET(listen_socks[i], fdset)) continue; fromlen = sizeof(from); newsock = accept(listen_socks[i], (struct sockaddr *)&from, &fromlen); if (newsock < 0) { if (errno != EINTR && errno != EWOULDBLOCK) error("accept: %.100s", strerror(errno)); continue; } if (fcntl(newsock, F_SETFL, 0) < 0) { error("newsock del O_NONBLOCK: %s", strerror(errno)); close(newsock); continue; } if (drop_connection(startups) == 1) { debug("drop connection #%d", startups); close(newsock); continue; } if (pipe(startup_p) == -1) { close(newsock); continue; } for (j = 0; j < options.max_startups; j++) if (startup_pipes[j] == -1) { startup_pipes[j] = startup_p[0]; if (maxfd < startup_p[0]) maxfd = startup_p[0]; startups++; break; } /* * Got connection. Fork a child to handle it, unless * we are in debugging mode. */ if (debug_flag) { /* * In debugging mode. Close the listening * socket, and start processing the * connection without forking. */ debug("Server will not fork when running in debugging mode."); close_listen_socks(); sock_in = newsock; sock_out = newsock; startup_pipe = -1; pid = getpid(); break; } else { /* * Normal production daemon. Fork, and have * the child process the connection. The * parent continues listening. */ if ((pid = fork()) == 0) { /* * Child. Close the listening and max_startup * sockets. Start using the accepted socket. * Reinitialize logging (since our pid has * changed). We break out of the loop to handle * the connection. */ startup_pipe = startup_p[1]; close_startup_pipes(); close_listen_socks(); sock_in = newsock; sock_out = newsock; log_init(__progname, options.log_level, options.log_facility, log_stderr); break; } } /* Parent. Stay in the loop. */ if (pid < 0) error("fork: %.100s", strerror(errno)); else debug("Forked child %ld.", (long)pid); close(startup_p[1]); /* Mark that the key has been used (it was "given" to the child). */ if ((options.protocol & SSH_PROTO_1) && key_used == 0) { /* Schedule server key regeneration alarm. */ signal(SIGALRM, key_regeneration_alarm); alarm(options.key_regeneration_time); key_used = 1; } arc4random_stir(); /* Close the new socket (the child is now taking care of it). */ close(newsock); } /* child process check (or debug mode) */ if (num_listen_socks < 0) break; } } /* This is the child processing a new connection. */ /* * Create a new session and process group since the 4.4BSD * setlogin() affects the entire process group. We don't * want the child to be able to affect the parent. */ if (!debug_flag && !inetd_flag && setsid() < 0) error("setsid: %.100s", strerror(errno)); /* * Disable the key regeneration alarm. We will not regenerate the * key since we are no longer in a position to give it to anyone. We * will not restart on SIGHUP since it no longer makes sense. */ alarm(0); signal(SIGALRM, SIG_DFL); signal(SIGHUP, SIG_DFL); signal(SIGTERM, SIG_DFL); signal(SIGQUIT, SIG_DFL); signal(SIGCHLD, SIG_DFL); /* Set keepalives if requested. */ if (options.keepalives && setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); /* * Register our connection. This turns encryption off because we do * not have a key. */ packet_set_connection(sock_in, sock_out); remote_port = get_remote_port(); remote_ip = get_remote_ipaddr(); #ifdef LIBWRAP /* Check whether logins are denied from this host. */ { struct request_info req; request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); fromhost(&req); if (!hosts_access(&req)) { debug("Connection refused by tcp wrapper"); refuse(&req); /* NOTREACHED */ fatal("libwrap refuse returns"); } } #endif /* LIBWRAP */ /* Log the connection. */ verbose("Connection from %.500s port %d", remote_ip, remote_port); /* * We don\'t want to listen forever unless the other side * successfully authenticates itself. So we set up an alarm which is * cleared after successful authentication. A limit of zero * indicates no limit. Note that we don\'t set the alarm in debugging * mode; it is just annoying to have the server exit just when you * are about to discover the bug. */ signal(SIGALRM, grace_alarm_handler); if (!debug_flag) alarm(options.login_grace_time); sshd_exchange_identification(sock_in, sock_out); /* * Check that the connection comes from a privileged port. * Rhosts-Authentication only makes sense from privileged * programs. Of course, if the intruder has root access on his local * machine, he can connect from any port. So do not use these * authentication methods from machines that you do not trust. */ if (options.rhosts_authentication && (remote_port >= IPPORT_RESERVED || remote_port < IPPORT_RESERVED / 2)) { debug("Rhosts Authentication disabled, " "originating port %d not trusted.", remote_port); options.rhosts_authentication = 0; } #if defined(KRB4) && !defined(KRB5) if (!packet_connection_is_ipv4() && options.kerberos_authentication) { debug("Kerberos Authentication disabled, only available for IPv4."); options.kerberos_authentication = 0; } #endif /* KRB4 && !KRB5 */ #ifdef AFS /* If machine has AFS, set process authentication group. */ if (k_hasafs()) { k_setpag(); k_unlog(); } #endif /* AFS */ packet_set_nonblocking(); if (use_privsep) if ((authctxt = privsep_preauth()) != NULL) goto authenticated; /* perform the key exchange */ /* authenticate user and start session */ if (compat20) { do_ssh2_kex(); authctxt = do_authentication2(); } else { do_ssh1_kex(); authctxt = do_authentication(); } /* * If we use privilege separation, the unprivileged child transfers * the current keystate and exits */ if (use_privsep) { mm_send_keystate(pmonitor); exit(0); } authenticated: /* * In privilege separation, we fork another child and prepare * file descriptor passing. */ if (use_privsep) { privsep_postauth(authctxt); /* the monitor process [priv] will not return */ if (!compat20) destroy_sensitive_data(); } /* Perform session preparation. */ do_authenticated(authctxt); /* The connection has been terminated. */ verbose("Closing connection to %.100s", remote_ip); packet_close(); if (use_privsep) mm_terminate(); exit(0); } /* * Decrypt session_key_int using our private server key and private host key * (key with larger modulus first). */ int ssh1_session_key(BIGNUM *session_key_int) { int rsafail = 0; if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { /* Server key has bigger modulus. */ if (BN_num_bits(sensitive_data.server_key->rsa->n) < BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", get_remote_ipaddr(), BN_num_bits(sensitive_data.server_key->rsa->n), BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), SSH_KEY_BITS_RESERVED); } if (rsa_private_decrypt(session_key_int, session_key_int, sensitive_data.server_key->rsa) <= 0) rsafail++; if (rsa_private_decrypt(session_key_int, session_key_int, sensitive_data.ssh1_host_key->rsa) <= 0) rsafail++; } else { /* Host key has bigger modulus (or they are equal). */ if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", get_remote_ipaddr(), BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), BN_num_bits(sensitive_data.server_key->rsa->n), SSH_KEY_BITS_RESERVED); } if (rsa_private_decrypt(session_key_int, session_key_int, sensitive_data.ssh1_host_key->rsa) < 0) rsafail++; if (rsa_private_decrypt(session_key_int, session_key_int, sensitive_data.server_key->rsa) < 0) rsafail++; } return (rsafail); } /* * SSH1 key exchange */ static void do_ssh1_kex(void) { int i, len; int rsafail = 0; BIGNUM *session_key_int; u_char session_key[SSH_SESSION_KEY_LENGTH]; u_char cookie[8]; u_int cipher_type, auth_mask, protocol_flags; u_int32_t rnd = 0; /* * Generate check bytes that the client must send back in the user * packet in order for it to be accepted; this is used to defy ip * spoofing attacks. Note that this only works against somebody * doing IP spoofing from a remote machine; any machine on the local * network can still see outgoing packets and catch the random * cookie. This only affects rhosts authentication, and this is one * of the reasons why it is inherently insecure. */ for (i = 0; i < 8; i++) { if (i % 4 == 0) rnd = arc4random(); cookie[i] = rnd & 0xff; rnd >>= 8; } /* * Send our public key. We include in the packet 64 bits of random * data that must be matched in the reply in order to prevent IP * spoofing. */ packet_start(SSH_SMSG_PUBLIC_KEY); for (i = 0; i < 8; i++) packet_put_char(cookie[i]); /* Store our public server RSA key. */ packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); packet_put_bignum(sensitive_data.server_key->rsa->e); packet_put_bignum(sensitive_data.server_key->rsa->n); /* Store our public host RSA key. */ packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); /* Put protocol flags. */ packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); /* Declare which ciphers we support. */ packet_put_int(cipher_mask_ssh1(0)); /* Declare supported authentication types. */ auth_mask = 0; if (options.rhosts_authentication) auth_mask |= 1 << SSH_AUTH_RHOSTS; if (options.rhosts_rsa_authentication) auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; if (options.rsa_authentication) auth_mask |= 1 << SSH_AUTH_RSA; #if defined(KRB4) || defined(KRB5) if (options.kerberos_authentication) auth_mask |= 1 << SSH_AUTH_KERBEROS; #endif #if defined(AFS) || defined(KRB5) if (options.kerberos_tgt_passing) auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; #endif #ifdef AFS if (options.afs_token_passing) auth_mask |= 1 << SSH_PASS_AFS_TOKEN; #endif if (options.challenge_response_authentication == 1) auth_mask |= 1 << SSH_AUTH_TIS; if (options.password_authentication) auth_mask |= 1 << SSH_AUTH_PASSWORD; packet_put_int(auth_mask); /* Send the packet and wait for it to be sent. */ packet_send(); packet_write_wait(); debug("Sent %d bit server key and %d bit host key.", BN_num_bits(sensitive_data.server_key->rsa->n), BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); /* Read clients reply (cipher type and session key). */ packet_read_expect(SSH_CMSG_SESSION_KEY); /* Get cipher type and check whether we accept this. */ cipher_type = packet_get_char(); if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) packet_disconnect("Warning: client selects unsupported cipher."); /* Get check bytes from the packet. These must match those we sent earlier with the public key packet. */ for (i = 0; i < 8; i++) if (cookie[i] != packet_get_char()) packet_disconnect("IP Spoofing check bytes do not match."); debug("Encryption type: %.200s", cipher_name(cipher_type)); /* Get the encrypted integer. */ if ((session_key_int = BN_new()) == NULL) fatal("do_ssh1_kex: BN_new failed"); packet_get_bignum(session_key_int); protocol_flags = packet_get_int(); packet_set_protocol_flags(protocol_flags); packet_check_eom(); /* Decrypt session_key_int using host/server keys */ rsafail = PRIVSEP(ssh1_session_key(session_key_int)); /* * Extract session key from the decrypted integer. The key is in the * least significant 256 bits of the integer; the first byte of the * key is in the highest bits. */ if (!rsafail) { BN_mask_bits(session_key_int, sizeof(session_key) * 8); len = BN_num_bytes(session_key_int); if (len < 0 || len > sizeof(session_key)) { error("do_connection: bad session key len from %s: " "session_key_int %d > sizeof(session_key) %lu", get_remote_ipaddr(), len, (u_long)sizeof(session_key)); rsafail++; } else { memset(session_key, 0, sizeof(session_key)); BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); compute_session_id(session_id, cookie, sensitive_data.ssh1_host_key->rsa->n, sensitive_data.server_key->rsa->n); /* * Xor the first 16 bytes of the session key with the * session id. */ for (i = 0; i < 16; i++) session_key[i] ^= session_id[i]; } } if (rsafail) { int bytes = BN_num_bytes(session_key_int); u_char *buf = xmalloc(bytes); MD5_CTX md; log("do_connection: generating a fake encryption key"); BN_bn2bin(session_key_int, buf); MD5_Init(&md); MD5_Update(&md, buf, bytes); MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); MD5_Final(session_key, &md); MD5_Init(&md); MD5_Update(&md, session_key, 16); MD5_Update(&md, buf, bytes); MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); MD5_Final(session_key + 16, &md); memset(buf, 0, bytes); xfree(buf); for (i = 0; i < 16; i++) session_id[i] = session_key[i] ^ session_key[i + 16]; } /* Destroy the private and public keys. No longer. */ destroy_sensitive_data(); if (use_privsep) mm_ssh1_session_id(session_id); /* Destroy the decrypted integer. It is no longer needed. */ BN_clear_free(session_key_int); /* Set the session key. From this on all communications will be encrypted. */ packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); /* Destroy our copy of the session key. It is no longer needed. */ memset(session_key, 0, sizeof(session_key)); debug("Received session key; encryption turned on."); /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ packet_start(SSH_SMSG_SUCCESS); packet_send(); packet_write_wait(); } /* * SSH2 key exchange: diffie-hellman-group1-sha1 */ static void do_ssh2_kex(void) { Kex *kex; if (options.ciphers != NULL) { myproposal[PROPOSAL_ENC_ALGS_CTOS] = myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; } myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); if (options.macs != NULL) { myproposal[PROPOSAL_MAC_ALGS_CTOS] = myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; } if (!options.compression) { myproposal[PROPOSAL_COMP_ALGS_CTOS] = myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; } myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); /* start key exchange */ kex = kex_setup(myproposal); kex->server = 1; kex->client_version_string=client_version_string; kex->server_version_string=server_version_string; kex->load_host_key=&get_hostkey_by_type; kex->host_key_index=&get_hostkey_index; xxx_kex = kex; dispatch_run(DISPATCH_BLOCK, &kex->done, kex); session_id2 = kex->session_id; session_id2_len = kex->session_id_len; #ifdef DEBUG_KEXDH /* send 1st encrypted/maced/compressed message */ packet_start(SSH2_MSG_IGNORE); packet_put_cstring("markus"); packet_send(); packet_write_wait(); #endif debug("KEX done"); }