blob: c5a92b5c6c69cb38ada133274dc2d7b42b598809 [file] [log] [blame]
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
2
3ssh.c
4
5Author: Tatu Ylonen <ylo@cs.hut.fi>
6
7Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 All rights reserved
9
10Created: Sat Mar 18 16:36:11 1995 ylo
11
12Ssh client program. This program can be used to log into a remote machine.
13The software supports strong authentication, encryption, and forwarding
14of X11, TCP/IP, and authentication connections.
15
16Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada.
17
18*/
19
20#include "includes.h"
21RCSID("$Id: ssh.c,v 1.1 1999/10/27 03:42:45 damien Exp $");
22
23#include "xmalloc.h"
24#include "ssh.h"
25#include "packet.h"
26#include "buffer.h"
27#include "authfd.h"
28#include "readconf.h"
29#include "uidswap.h"
30
31/* Flag indicating whether debug mode is on. This can be set on the
32 command line. */
33int debug_flag = 0;
34
35/* Flag indicating whether quiet mode is on. */
36int quiet_flag = 0;
37
38/* Flag indicating whether to allocate a pseudo tty. This can be set on the
39 command line, and is automatically set if no command is given on the command
40 line. */
41int tty_flag = 0;
42
43/* Flag indicating that nothing should be read from stdin. This can be set
44 on the command line. */
45int stdin_null_flag = 0;
46
47/* Flag indicating that ssh should fork after authentication. This is useful
48 so that the pasphrase can be entered manually, and then ssh goes to the
49 background. */
50int fork_after_authentication_flag = 0;
51
52/* General data structure for command line options and options configurable
53 in configuration files. See readconf.h. */
54Options options;
55
56/* Name of the host we are connecting to. This is the name given on the
57 command line, or the HostName specified for the user-supplied name
58 in a configuration file. */
59char *host;
60
61/* socket address the host resolves to */
62struct sockaddr_in hostaddr;
63
64/* Flag to indicate that we have received a window change signal which has
65 not yet been processed. This will cause a message indicating the new
66 window size to be sent to the server a little later. This is volatile
67 because this is updated in a signal handler. */
68volatile int received_window_change_signal = 0;
69
70/* Value of argv[0] (set in the main program). */
71char *av0;
72
73/* Flag indicating whether we have a valid host private key loaded. */
74int host_private_key_loaded = 0;
75
76/* Host private key. */
77RSA *host_private_key = NULL;
78
79/* Original real UID. */
80uid_t original_real_uid;
81
82/* Prints a help message to the user. This function never returns. */
83
84void
85usage()
86{
87 fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
88 fprintf(stderr, "Options:\n");
89 fprintf(stderr, " -l user Log in using this user name.\n");
90 fprintf(stderr, " -n Redirect input from /dev/null.\n");
91 fprintf(stderr, " -a Disable authentication agent forwarding.\n");
92#ifdef AFS
93 fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
94#endif /* AFS */
95 fprintf(stderr, " -x Disable X11 connection forwarding.\n");
96 fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
97 fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
98 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
99 fprintf(stderr, " -V Display version number only.\n");
100 fprintf(stderr, " -P Don't allocate a privileged port.\n");
101 fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
102 fprintf(stderr, " -f Fork into background after authentication.\n");
103 fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
104
105 fprintf(stderr, " -c cipher Select encryption algorithm: "
106 "``3des'', "
107 "``blowfish''\n");
108 fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
109 fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
110 fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
111 fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
112 fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
113 fprintf(stderr, " -C Enable compression.\n");
114 fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
115 fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
116 exit(1);
117}
118
119/* Connects to the given host using rsh (or prints an error message and exits
120 if rsh is not available). This function never returns. */
121
122void
123rsh_connect(char *host, char *user, Buffer *command)
124{
125 char *args[10];
126 int i;
127
128 log("Using rsh. WARNING: Connection will not be encrypted.");
129 /* Build argument list for rsh. */
130 i = 0;
131 args[i++] = _PATH_RSH;
132 args[i++] = host; /* may have to come after user on some systems */
133 if (user)
134 {
135 args[i++] = "-l";
136 args[i++] = user;
137 }
138 if (buffer_len(command) > 0)
139 {
140 buffer_append(command, "\0", 1);
141 args[i++] = buffer_ptr(command);
142 }
143 args[i++] = NULL;
144 if (debug_flag)
145 {
146 for (i = 0; args[i]; i++)
147 {
148 if (i != 0)
149 fprintf(stderr, " ");
150 fprintf(stderr, "%s", args[i]);
151 }
152 fprintf(stderr, "\n");
153 }
154 execv(_PATH_RSH, args);
155 perror(_PATH_RSH);
156 exit(1);
157}
158
159/* Main program for the ssh client. */
160
161uid_t original_real_uid;
162
163int
164main(int ac, char **av)
165{
166 int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd;
167 char *optarg, *cp, buf[256];
168 Buffer command;
169 struct winsize ws;
170 struct stat st;
171 struct passwd *pw, pwcopy;
172 int interactive = 0, dummy;
173 uid_t original_effective_uid;
174 int plen;
175
176 /* Save the original real uid. It will be needed later (uid-swapping may
177 clobber the real uid). */
178 original_real_uid = getuid();
179 original_effective_uid = geteuid();
180
181 /* If we are installed setuid root be careful to not drop core. */
182 if (original_real_uid != original_effective_uid)
183 {
184 struct rlimit rlim;
185 rlim.rlim_cur = rlim.rlim_max = 0;
186 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
187 fatal("setrlimit failed: %.100s", strerror(errno));
188 }
189
190 /* Use uid-swapping to give up root privileges for the duration of option
191 processing. We will re-instantiate the rights when we are ready to
192 create the privileged port, and will permanently drop them when the
193 port has been created (actually, when the connection has been made, as
194 we may need to create the port several times). */
195 temporarily_use_uid(original_real_uid);
196
197 /* Set our umask to something reasonable, as some files are created with
198 the default umask. This will make them world-readable but writable
199 only by the owner, which is ok for all files for which we don't set
200 the modes explicitly. */
201 umask(022);
202
203 /* Save our own name. */
204 av0 = av[0];
205
206 /* Initialize option structure to indicate that no values have been set. */
207 initialize_options(&options);
208
209 /* Parse command-line arguments. */
210 host = NULL;
211
212 /* If program name is not one of the standard names, use it as host name. */
213 if (strchr(av0, '/'))
214 cp = strrchr(av0, '/') + 1;
215 else
216 cp = av0;
217 if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
218 strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
219 host = cp;
220
221 for (optind = 1; optind < ac; optind++)
222 {
223 if (av[optind][0] != '-')
224 {
225 if (host)
226 break;
227 if ((cp = strchr(av[optind], '@'))) {
228 options.user = av[optind];
229 *cp = '\0';
230 host = ++cp;
231 }
232 else
233 host = av[optind];
234 continue;
235 }
236 opt = av[optind][1];
237 if (!opt)
238 usage();
239 if (strchr("eilcpLRo", opt)) /* options with arguments */
240 {
241 optarg = av[optind] + 2;
242 if (strcmp(optarg, "") == 0)
243 {
244 if (optind >= ac - 1)
245 usage();
246 optarg = av[++optind];
247 }
248 }
249 else
250 {
251 if (av[optind][2])
252 usage();
253 optarg = NULL;
254 }
255 switch (opt)
256 {
257 case 'n':
258 stdin_null_flag = 1;
259 break;
260
261 case 'f':
262 fork_after_authentication_flag = 1;
263 stdin_null_flag = 1;
264 break;
265
266 case 'x':
267 options.forward_x11 = 0;
268 break;
269
270 case 'X':
271 options.forward_x11 = 1;
272 break;
273
274 case 'g':
275 options.gateway_ports = 1;
276 break;
277
278 case 'P':
279 options.use_privileged_port = 0;
280 break;
281
282 case 'a':
283 options.forward_agent = 0;
284 break;
285#ifdef AFS
286 case 'k':
287 options.kerberos_tgt_passing = 0;
288 options.afs_token_passing = 0;
289 break;
290#endif
291 case 'i':
292 if (stat(optarg, &st) < 0)
293 {
294 fprintf(stderr, "Warning: Identity file %s does not exist.\n",
295 optarg);
296 break;
297 }
298 if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
299 fatal("Too many identity files specified (max %d)",
300 SSH_MAX_IDENTITY_FILES);
301 options.identity_files[options.num_identity_files++] =
302 xstrdup(optarg);
303 break;
304
305 case 't':
306 tty_flag = 1;
307 break;
308
309 case 'v':
310 case 'V':
311 debug_flag = 1;
312 fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
313 SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
314 fprintf(stderr, "Compiled with SSL.\n");
315 if (opt == 'V')
316 exit(0);
317 break;
318
319 case 'q':
320 quiet_flag = 1;
321 break;
322
323 case 'e':
324 if (optarg[0] == '^' && optarg[2] == 0 &&
325 (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128)
326 options.escape_char = (unsigned char)optarg[1] & 31;
327 else
328 if (strlen(optarg) == 1)
329 options.escape_char = (unsigned char)optarg[0];
330 else
331 if (strcmp(optarg, "none") == 0)
332 options.escape_char = -2;
333 else
334 {
335 fprintf(stderr, "Bad escape character '%s'.\n", optarg);
336 exit(1);
337 }
338 break;
339
340 case 'c':
341 options.cipher = cipher_number(optarg);
342 if (options.cipher == -1)
343 {
344 fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
345 exit(1);
346 }
347 break;
348
349 case 'p':
350 options.port = atoi(optarg);
351 if (options.port < 1 || options.port > 65535)
352 {
353 fprintf(stderr, "Bad port %s.\n", optarg);
354 exit(1);
355 }
356 break;
357
358 case 'l':
359 options.user = optarg;
360 break;
361
362 case 'R':
363 if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
364 &fwd_host_port) != 3)
365 {
366 fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
367 usage();
368 /*NOTREACHED*/
369 }
370 add_remote_forward(&options, fwd_port, buf, fwd_host_port);
371 break;
372
373 case 'L':
374 if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
375 &fwd_host_port) != 3)
376 {
377 fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
378 usage();
379 /*NOTREACHED*/
380 }
381 add_local_forward(&options, fwd_port, buf, fwd_host_port);
382 break;
383
384 case 'C':
385 options.compression = 1;
386 break;
387
388 case 'o':
389 dummy = 1;
390 process_config_line(&options, host ? host : "", optarg,
391 "command-line", 0, &dummy);
392 break;
393
394 default:
395 usage();
396 }
397 }
398
399 /* Check that we got a host name. */
400 if (!host)
401 usage();
402
403 /* check if RSA support exists */
404 if (rsa_alive() == 0) {
405 extern char *__progname;
406
407 fprintf(stderr,
408 "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
409 __progname);
410 exit(1);
411 }
412
413 /* Initialize the command to execute on remote host. */
414 buffer_init(&command);
415
416 /* Save the command to execute on the remote host in a buffer. There is
417 no limit on the length of the command, except by the maximum packet
418 size. Also sets the tty flag if there is no command. */
419 if (optind == ac)
420 {
421 /* No command specified - execute shell on a tty. */
422 tty_flag = 1;
423 }
424 else
425 {
426 /* A command has been specified. Store it into the buffer. */
427 for (i = optind; i < ac; i++)
428 {
429 if (i > optind)
430 buffer_append(&command, " ", 1);
431 buffer_append(&command, av[i], strlen(av[i]));
432 }
433 }
434
435 /* Cannot fork to background if no command. */
436 if (fork_after_authentication_flag && buffer_len(&command) == 0)
437 fatal("Cannot fork into background without a command to execute.");
438
439 /* Allocate a tty by default if no command specified. */
440 if (buffer_len(&command) == 0)
441 tty_flag = 1;
442
443 /* Do not allocate a tty if stdin is not a tty. */
444 if (!isatty(fileno(stdin)))
445 {
446 if (tty_flag)
447 fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
448 tty_flag = 0;
449 }
450
451 /* Get user data. */
452 pw = getpwuid(original_real_uid);
453 if (!pw)
454 {
455 fprintf(stderr, "You don't exist, go away!\n");
456 exit(1);
457 }
458
459 /* Take a copy of the returned structure. */
460 memset(&pwcopy, 0, sizeof(pwcopy));
461 pwcopy.pw_name = xstrdup(pw->pw_name);
462 pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
463 pwcopy.pw_uid = pw->pw_uid;
464 pwcopy.pw_gid = pw->pw_gid;
465 pwcopy.pw_dir = xstrdup(pw->pw_dir);
466 pwcopy.pw_shell = xstrdup(pw->pw_shell);
467 pw = &pwcopy;
468
469 /* Initialize "log" output. Since we are the client all output actually
470 goes to the terminal. */
471 log_init(av[0], 1, debug_flag, quiet_flag, SYSLOG_FACILITY_USER);
472
473 /* Read per-user configuration file. */
474 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
475 read_config_file(buf, host, &options);
476
477 /* Read systemwide configuration file. */
478 read_config_file(HOST_CONFIG_FILE, host, &options);
479
480 /* Fill configuration defaults. */
481 fill_default_options(&options);
482 if (options.user == NULL)
483 options.user = xstrdup(pw->pw_name);
484
485 if (options.hostname != NULL)
486 host = options.hostname;
487
488 /* Find canonic host name. */
489 if (strchr(host, '.') == 0)
490 {
491 struct hostent *hp = gethostbyname(host);
492 if (hp != 0)
493 {
494 if (strchr(hp->h_name, '.') != 0)
495 host = xstrdup(hp->h_name);
496 else if (hp->h_aliases != 0
497 && hp->h_aliases[0] != 0
498 && strchr(hp->h_aliases[0], '.') != 0)
499 host = xstrdup(hp->h_aliases[0]);
500 }
501 }
502
503 /* Disable rhosts authentication if not running as root. */
504 if (original_effective_uid != 0)
505 {
506 options.rhosts_authentication = 0;
507 options.rhosts_rsa_authentication = 0;
508 }
509
510 /* If using rsh has been selected, exec it now (without trying anything
511 else). Note that we must release privileges first. */
512 if (options.use_rsh)
513 {
514 /* Restore our superuser privileges. This must be done before
515 permanently setting the uid. */
516 restore_uid();
517
518 /* Switch to the original uid permanently. */
519 permanently_set_uid(original_real_uid);
520
521 /* Execute rsh. */
522 rsh_connect(host, options.user, &command);
523 fatal("rsh_connect returned");
524 }
525
526 /* Restore our superuser privileges. */
527 restore_uid();
528
529 /* Open a connection to the remote host. This needs root privileges if
530 rhosts_{rsa_}authentication is true. */
531
532 if (!options.use_privileged_port)
533 {
534 options.rhosts_authentication = 0;
535 options.rhosts_rsa_authentication = 0;
536 }
537
538 ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts,
539 !options.rhosts_authentication &&
540 !options.rhosts_rsa_authentication,
541 original_real_uid, options.proxy_command);
542
543 /* If we successfully made the connection, load the host private key in
544 case we will need it later for combined rsa-rhosts authentication.
545 This must be done before releasing extra privileges, because the file
546 is only readable by root. */
547 if (ok)
548 {
549 host_private_key = RSA_new();
550 if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
551 host_private_key_loaded = 1;
552 }
553
554 /* Get rid of any extra privileges that we may have. We will no longer need
555 them. Also, extra privileges could make it very hard to read identity
556 files and other non-world-readable files from the user's home directory
557 if it happens to be on a NFS volume where root is mapped to nobody. */
558 permanently_set_uid(original_real_uid);
559
560 /* Now that we are back to our own permissions, create ~/.ssh directory
561 if it doesn\'t already exist. */
562 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
563 if (stat(buf, &st) < 0)
564 if (mkdir(buf, 0755) < 0)
565 error("Could not create directory '%.200s'.", buf);
566
567 /* Check if the connection failed, and try "rsh" if appropriate. */
568 if (!ok)
569 {
570 if (options.port != 0)
571 log("Secure connection to %.100s on port %d refused%.100s.",
572 host, options.port,
573 options.fallback_to_rsh ? "; reverting to insecure method" : "");
574 else
575 log("Secure connection to %.100s refused%.100s.", host,
576 options.fallback_to_rsh ? "; reverting to insecure method" : "");
577
578 if (options.fallback_to_rsh)
579 {
580 rsh_connect(host, options.user, &command);
581 fatal("rsh_connect returned");
582 }
583 exit(1);
584 }
585
586 /* Expand ~ in options.identity_files. */
587 for (i = 0; i < options.num_identity_files; i++)
588 options.identity_files[i] =
589 tilde_expand_filename(options.identity_files[i], original_real_uid);
590
591 /* Expand ~ in known host file names. */
592 options.system_hostfile = tilde_expand_filename(options.system_hostfile,
593 original_real_uid);
594 options.user_hostfile = tilde_expand_filename(options.user_hostfile,
595 original_real_uid);
596
597 /* Log into the remote system. This never returns if the login fails. */
598 ssh_login(host_private_key_loaded, host_private_key,
599 host, &hostaddr, &options, original_real_uid);
600
601 /* We no longer need the host private key. Clear it now. */
602 if (host_private_key_loaded)
603 RSA_free(host_private_key); /* Destroys contents safely */
604
605 /* Close connection cleanly after attack. */
606 cipher_attack_detected = packet_disconnect;
607
608 /* If requested, fork and let ssh continue in the background. */
609 if (fork_after_authentication_flag)
610 {
611 int ret = fork();
612 if (ret == -1)
613 fatal("fork failed: %.100s", strerror(errno));
614 if (ret != 0)
615 exit(0);
616 setsid();
617 }
618
619 /* Enable compression if requested. */
620 if (options.compression)
621 {
622 debug("Requesting compression at level %d.", options.compression_level);
623
624 if (options.compression_level < 1 || options.compression_level > 9)
625 fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
626
627 /* Send the request. */
628 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
629 packet_put_int(options.compression_level);
630 packet_send();
631 packet_write_wait();
632 type = packet_read(&plen);
633 if (type == SSH_SMSG_SUCCESS)
634 packet_start_compression(options.compression_level);
635 else if (type == SSH_SMSG_FAILURE)
636 log("Warning: Remote host refused compression.");
637 else
638 packet_disconnect("Protocol error waiting for compression response.");
639 }
640
641 /* Allocate a pseudo tty if appropriate. */
642 if (tty_flag)
643 {
644 debug("Requesting pty.");
645
646 /* Start the packet. */
647 packet_start(SSH_CMSG_REQUEST_PTY);
648
649 /* Store TERM in the packet. There is no limit on the length of the
650 string. */
651 cp = getenv("TERM");
652 if (!cp)
653 cp = "";
654 packet_put_string(cp, strlen(cp));
655
656 /* Store window size in the packet. */
657 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
658 memset(&ws, 0, sizeof(ws));
659 packet_put_int(ws.ws_row);
660 packet_put_int(ws.ws_col);
661 packet_put_int(ws.ws_xpixel);
662 packet_put_int(ws.ws_ypixel);
663
664 /* Store tty modes in the packet. */
665 tty_make_modes(fileno(stdin));
666
667 /* Send the packet, and wait for it to leave. */
668 packet_send();
669 packet_write_wait();
670
671 /* Read response from the server. */
672 type = packet_read(&plen);
673 if (type == SSH_SMSG_SUCCESS)
674 interactive = 1;
675 else if (type == SSH_SMSG_FAILURE)
676 log("Warning: Remote host failed or refused to allocate a pseudo tty.");
677 else
678 packet_disconnect("Protocol error waiting for pty request response.");
679 }
680
681 /* Request X11 forwarding if enabled and DISPLAY is set. */
682 if (options.forward_x11 && getenv("DISPLAY") != NULL)
683 {
684 char line[512], proto[512], data[512];
685 FILE *f;
686 int forwarded = 0, got_data = 0, i;
687
688#ifdef XAUTH_PATH
689 /* Try to get Xauthority information for the display. */
690 snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
691 XAUTH_PATH, getenv("DISPLAY"));
692 f = popen(line, "r");
693 if (f && fgets(line, sizeof(line), f) &&
694 sscanf(line, "%*s %s %s", proto, data) == 2)
695 got_data = 1;
696 if (f)
697 pclose(f);
698#endif /* XAUTH_PATH */
699 /* If we didn't get authentication data, just make up some data. The
700 forwarding code will check the validity of the response anyway, and
701 substitute this data. The X11 server, however, will ignore this
702 fake data and use whatever authentication mechanisms it was using
703 otherwise for the local connection. */
704 if (!got_data)
705 {
706 u_int32_t rand = 0;
707
708 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
709 for (i = 0; i < 16; i++) {
710 if (i % 4 == 0)
711 rand = arc4random();
712 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
713 rand >>= 8;
714 }
715 }
716
717 /* Got local authentication reasonable information. Request forwarding
718 with authentication spoofing. */
719 debug("Requesting X11 forwarding with authentication spoofing.");
720 x11_request_forwarding_with_spoofing(proto, data);
721
722 /* Read response from the server. */
723 type = packet_read(&plen);
724 if (type == SSH_SMSG_SUCCESS)
725 {
726 forwarded = 1;
727 interactive = 1;
728 }
729 else if (type == SSH_SMSG_FAILURE)
730 log("Warning: Remote host denied X11 forwarding.");
731 else
732 packet_disconnect("Protocol error waiting for X11 forwarding");
733 }
734
735 /* Tell the packet module whether this is an interactive session. */
736 packet_set_interactive(interactive, options.keepalives);
737
738 /* Clear agent forwarding if we don\'t have an agent. */
739 authfd = ssh_get_authentication_socket();
740 if (authfd < 0)
741 options.forward_agent = 0;
742 else
743 ssh_close_authentication_socket(authfd);
744
745 /* Request authentication agent forwarding if appropriate. */
746 if (options.forward_agent)
747 {
748 debug("Requesting authentication agent forwarding.");
749 auth_request_forwarding();
750
751 /* Read response from the server. */
752 type = packet_read(&plen);
753 packet_integrity_check(plen, 0, type);
754 if (type != SSH_SMSG_SUCCESS)
755 log("Warning: Remote host denied authentication agent forwarding.");
756 }
757
758 /* Initiate local TCP/IP port forwardings. */
759 for (i = 0; i < options.num_local_forwards; i++)
760 {
761 debug("Connections to local port %d forwarded to remote address %.200s:%d",
762 options.local_forwards[i].port, options.local_forwards[i].host,
763 options.local_forwards[i].host_port);
764 channel_request_local_forwarding(options.local_forwards[i].port,
765 options.local_forwards[i].host,
766 options.local_forwards[i].host_port);
767 }
768
769 /* Initiate remote TCP/IP port forwardings. */
770 for (i = 0; i < options.num_remote_forwards; i++)
771 {
772 debug("Connections to remote port %d forwarded to local address %.200s:%d",
773 options.remote_forwards[i].port, options.remote_forwards[i].host,
774 options.remote_forwards[i].host_port);
775 channel_request_remote_forwarding(options.remote_forwards[i].port,
776 options.remote_forwards[i].host,
777 options.remote_forwards[i].host_port);
778 }
779
780 /* If a command was specified on the command line, execute the command now.
781 Otherwise request the server to start a shell. */
782 if (buffer_len(&command) > 0)
783 {
784 int len = buffer_len(&command);
785 if (len > 900)
786 len = 900;
787 debug("Sending command: %.*s", len, buffer_ptr(&command));
788 packet_start(SSH_CMSG_EXEC_CMD);
789 packet_put_string(buffer_ptr(&command), buffer_len(&command));
790 packet_send();
791 packet_write_wait();
792 }
793 else
794 {
795 debug("Requesting shell.");
796 packet_start(SSH_CMSG_EXEC_SHELL);
797 packet_send();
798 packet_write_wait();
799 }
800
801 /* Enter the interactive session. */
802 exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
803
804 /* Close the connection to the remote host. */
805 packet_close();
806
807 /* Exit with the status returned by the program on the remote side. */
808 exit(exit_status);
809}