xref: /freebsd/crypto/openssh/ssh.h (revision 23f282aa31e9b6fceacd449020e936e98d6f2298)
1 /*
2  *
3  * ssh.h
4  *
5  * Author: Tatu Ylonen <ylo@cs.hut.fi>
6  *
7  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8  *                    All rights reserved
9  *
10  * Created: Fri Mar 17 17:09:37 1995 ylo
11  *
12  * Generic header file for ssh.
13  *
14  * $FreeBSD$
15  */
16 
17 /* RCSID("$Id: ssh.h,v 1.34 2000/03/23 22:15:33 markus Exp $"); */
18 
19 #ifndef SSH_H
20 #define SSH_H
21 
22 #include "rsa.h"
23 #include "cipher.h"
24 
25 /*
26  * The default cipher used if IDEA is not supported by the remote host. It is
27  * recommended that this be one of the mandatory ciphers (DES, 3DES), though
28  * that is not required.
29  */
30 #define SSH_FALLBACK_CIPHER	SSH_CIPHER_3DES
31 
32 /* Cipher used for encrypting authentication files. */
33 #define SSH_AUTHFILE_CIPHER	SSH_CIPHER_3DES
34 
35 /* Default port number. */
36 #define SSH_DEFAULT_PORT	22
37 
38 /* Maximum number of TCP/IP ports forwarded per direction. */
39 #define SSH_MAX_FORWARDS_PER_DIRECTION	100
40 
41 /*
42  * Maximum number of RSA authentication identity files that can be specified
43  * in configuration files or on the command line.
44  */
45 #define SSH_MAX_IDENTITY_FILES		100
46 
47 /*
48  * Major protocol version.  Different version indicates major incompatiblity
49  * that prevents communication.
50  */
51 #define PROTOCOL_MAJOR		1
52 
53 /*
54  * Minor protocol version.  Different version indicates minor incompatibility
55  * that does not prevent interoperation.
56  */
57 #define PROTOCOL_MINOR		5
58 
59 /*
60  * Name for the service.  The port named by this service overrides the
61  * default port if present.
62  */
63 #define SSH_SERVICE_NAME	"ssh"
64 
65 #define ETCDIR			"/etc/ssh"
66 #define PIDDIR			"/var/run"
67 
68 /*
69  * System-wide file containing host keys of known hosts.  This file should be
70  * world-readable.
71  */
72 #define SSH_SYSTEM_HOSTFILE	ETCDIR "/ssh_known_hosts"
73 
74 /*
75  * Of these, ssh_host_key must be readable only by root, whereas ssh_config
76  * should be world-readable.
77  */
78 #define HOST_KEY_FILE		ETCDIR "/ssh_host_key"
79 #define SERVER_CONFIG_FILE	ETCDIR "/sshd_config"
80 #define HOST_CONFIG_FILE	ETCDIR "/ssh_config"
81 
82 #define SSH_PROGRAM		"/usr/bin/ssh"
83 
84 /*
85  * The process id of the daemon listening for connections is saved here to
86  * make it easier to kill the correct daemon when necessary.
87  */
88 #define SSH_DAEMON_PID_FILE	PIDDIR "/sshd.pid"
89 
90 /*
91  * The directory in user\'s home directory in which the files reside. The
92  * directory should be world-readable (though not all files are).
93  */
94 #define SSH_USER_DIR		".ssh"
95 
96 /*
97  * Per-user file containing host keys of known hosts.  This file need not be
98  * readable by anyone except the user him/herself, though this does not
99  * contain anything particularly secret.
100  */
101 #define SSH_USER_HOSTFILE	"~/.ssh/known_hosts"
102 
103 /*
104  * Name of the default file containing client-side authentication key. This
105  * file should only be readable by the user him/herself.
106  */
107 #define SSH_CLIENT_IDENTITY	".ssh/identity"
108 
109 /*
110  * Configuration file in user\'s home directory.  This file need not be
111  * readable by anyone but the user him/herself, but does not contain anything
112  * particularly secret.  If the user\'s home directory resides on an NFS
113  * volume where root is mapped to nobody, this may need to be world-readable.
114  */
115 #define SSH_USER_CONFFILE	".ssh/config"
116 
117 /*
118  * File containing a list of those rsa keys that permit logging in as this
119  * user.  This file need not be readable by anyone but the user him/herself,
120  * but does not contain anything particularly secret.  If the user\'s home
121  * directory resides on an NFS volume where root is mapped to nobody, this
122  * may need to be world-readable.  (This file is read by the daemon which is
123  * running as root.)
124  */
125 #define SSH_USER_PERMITTED_KEYS	".ssh/authorized_keys"
126 
127 /*
128  * Per-user and system-wide ssh "rc" files.  These files are executed with
129  * /bin/sh before starting the shell or command if they exist.  They will be
130  * passed "proto cookie" as arguments if X11 forwarding with spoofing is in
131  * use.  xauth will be run if neither of these exists.
132  */
133 #define SSH_USER_RC		".ssh/rc"
134 #define SSH_SYSTEM_RC		ETCDIR "/sshrc"
135 
136 /*
137  * Ssh-only version of /etc/hosts.equiv.  Additionally, the daemon may use
138  * ~/.rhosts and /etc/hosts.equiv if rhosts authentication is enabled.
139  */
140 #define SSH_HOSTS_EQUIV		ETCDIR "/shosts.equiv"
141 
142 /*
143  * Name of the environment variable containing the pathname of the
144  * authentication socket.
145  */
146 #define SSH_AUTHSOCKET_ENV_NAME	"SSH_AUTH_SOCK"
147 
148 /*
149  * Name of the environment variable containing the pathname of the
150  * authentication socket.
151  */
152 #define SSH_AGENTPID_ENV_NAME	"SSH_AGENT_PID"
153 
154 /*
155  * Default path to ssh-askpass used by ssh-add,
156  * environment variable for overwriting the default location
157  */
158 #define SSH_ASKPASS_DEFAULT	"/usr/X11R6/bin/ssh-askpass"
159 #define SSH_ASKPASS_ENV		"SSH_ASKPASS"
160 
161 /*
162  * Force host key length and server key length to differ by at least this
163  * many bits.  This is to make double encryption with rsaref work.
164  */
165 #define SSH_KEY_BITS_RESERVED		128
166 
167 /*
168  * Length of the session key in bytes.  (Specified as 256 bits in the
169  * protocol.)
170  */
171 #define SSH_SESSION_KEY_LENGTH		32
172 
173 /* Name of Kerberos service for SSH to use. */
174 #define KRB4_SERVICE_NAME		"rcmd"
175 
176 /*
177  * Authentication methods.  New types can be added, but old types should not
178  * be removed for compatibility.  The maximum allowed value is 31.
179  */
180 #define SSH_AUTH_RHOSTS		1
181 #define SSH_AUTH_RSA		2
182 #define SSH_AUTH_PASSWORD	3
183 #define SSH_AUTH_RHOSTS_RSA	4
184 #define SSH_AUTH_TIS		5
185 #define SSH_AUTH_KRB4		6
186 #define SSH_PASS_KRB4_TGT	7
187 				/* 8 to 15 are reserved */
188 #define SSH_PASS_AFS_TOKEN	21
189 
190 #define SSH_AUTH_KRB5		29
191 #define SSH_PASS_KRB5_TGT	30
192 
193 /* Protocol flags.  These are bit masks. */
194 #define SSH_PROTOFLAG_SCREEN_NUMBER	1	/* X11 forwarding includes screen */
195 #define SSH_PROTOFLAG_HOST_IN_FWD_OPEN	2	/* forwarding opens contain host */
196 
197 /*
198  * Definition of message types.  New values can be added, but old values
199  * should not be removed or without careful consideration of the consequences
200  * for compatibility.  The maximum value is 254; value 255 is reserved for
201  * future extension.
202  */
203 /* Message name */			/* msg code */	/* arguments */
204 #define SSH_MSG_NONE				0	/* no message */
205 #define SSH_MSG_DISCONNECT			1	/* cause (string) */
206 #define SSH_SMSG_PUBLIC_KEY			2	/* ck,msk,srvk,hostk */
207 #define SSH_CMSG_SESSION_KEY			3	/* key (BIGNUM) */
208 #define SSH_CMSG_USER				4	/* user (string) */
209 #define SSH_CMSG_AUTH_RHOSTS			5	/* user (string) */
210 #define SSH_CMSG_AUTH_RSA			6	/* modulus (BIGNUM) */
211 #define SSH_SMSG_AUTH_RSA_CHALLENGE		7	/* int (BIGNUM) */
212 #define SSH_CMSG_AUTH_RSA_RESPONSE		8	/* int (BIGNUM) */
213 #define SSH_CMSG_AUTH_PASSWORD			9	/* pass (string) */
214 #define SSH_CMSG_REQUEST_PTY		        10	/* TERM, tty modes */
215 #define SSH_CMSG_WINDOW_SIZE		        11	/* row,col,xpix,ypix */
216 #define SSH_CMSG_EXEC_SHELL			12	/* */
217 #define SSH_CMSG_EXEC_CMD			13	/* cmd (string) */
218 #define SSH_SMSG_SUCCESS			14	/* */
219 #define SSH_SMSG_FAILURE			15	/* */
220 #define SSH_CMSG_STDIN_DATA			16	/* data (string) */
221 #define SSH_SMSG_STDOUT_DATA			17	/* data (string) */
222 #define SSH_SMSG_STDERR_DATA			18	/* data (string) */
223 #define SSH_CMSG_EOF				19	/* */
224 #define SSH_SMSG_EXITSTATUS			20	/* status (int) */
225 #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION	21	/* channel (int) */
226 #define SSH_MSG_CHANNEL_OPEN_FAILURE		22	/* channel (int) */
227 #define SSH_MSG_CHANNEL_DATA			23	/* ch,data (int,str) */
228 #define SSH_MSG_CHANNEL_CLOSE			24	/* channel (int) */
229 #define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION	25	/* channel (int) */
230 /*      SSH_CMSG_X11_REQUEST_FORWARDING         26         OBSOLETE */
231 #define SSH_SMSG_X11_OPEN			27	/* channel (int) */
232 #define SSH_CMSG_PORT_FORWARD_REQUEST		28	/* p,host,hp (i,s,i) */
233 #define SSH_MSG_PORT_OPEN			29	/* ch,h,p (i,s,i) */
234 #define SSH_CMSG_AGENT_REQUEST_FORWARDING	30	/* */
235 #define SSH_SMSG_AGENT_OPEN			31	/* port (int) */
236 #define SSH_MSG_IGNORE				32	/* string */
237 #define SSH_CMSG_EXIT_CONFIRMATION		33	/* */
238 #define SSH_CMSG_X11_REQUEST_FORWARDING		34	/* proto,data (s,s) */
239 #define SSH_CMSG_AUTH_RHOSTS_RSA		35	/* user,mod (s,mpi) */
240 #define SSH_MSG_DEBUG				36	/* string */
241 #define SSH_CMSG_REQUEST_COMPRESSION		37	/* level 1-9 (int) */
242 #define SSH_CMSG_MAX_PACKET_SIZE		38	/* size 4k-1024k (int) */
243 #define SSH_CMSG_AUTH_TIS			39	/* we use this for s/key */
244 #define SSH_SMSG_AUTH_TIS_CHALLENGE		40	/* challenge (string) */
245 #define SSH_CMSG_AUTH_TIS_RESPONSE		41	/* response (string) */
246 #define SSH_CMSG_AUTH_KRB4			42	/* (KTEXT) */
247 #define SSH_SMSG_AUTH_KRB4_RESPONSE		43	/* (KTEXT) */
248 #define SSH_CMSG_HAVE_KRB4_TGT			44	/* credentials (s) */
249 #define SSH_CMSG_HAVE_AFS_TOKEN			65	/* token (s) */
250 
251 #define SSH_CMSG_AUTH_KRB5			110
252 #define SSH_SMSG_AUTH_KRB5_RESPONSE		111
253 #define	SSH_CMSG_HAVE_KRB5_TGT			112
254 
255 /*------------ definitions for login.c -------------*/
256 
257 /*
258  * Returns the time when the user last logged in.  Returns 0 if the
259  * information is not available.  This must be called before record_login.
260  * The host from which the user logged in is stored in buf.
261  */
262 unsigned long
263 get_last_login_time(uid_t uid, const char *logname,
264     char *buf, unsigned int bufsize);
265 
266 /*
267  * Records that the user has logged in.  This does many things normally done
268  * by login(1).
269  */
270 void
271 record_login(int pid, const char *ttyname, const char *user, uid_t uid,
272     const char *host, struct sockaddr *addr);
273 
274 /*
275  * Records that the user has logged out.  This does many thigs normally done
276  * by login(1) or init.
277  */
278 void    record_logout(int pid, const char *ttyname);
279 
280 /*------------ definitions for sshconnect.c ----------*/
281 
282 /*
283  * Opens a TCP/IP connection to the remote server on the given host.  If port
284  * is 0, the default port will be used.  If anonymous is zero, a privileged
285  * port will be allocated to make the connection. This requires super-user
286  * privileges if anonymous is false. Connection_attempts specifies the
287  * maximum number of tries, one per second.  This returns true on success,
288  * and zero on failure.  If the connection is successful, this calls
289  * packet_set_connection for the connection.
290  */
291 int
292 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
293     u_short port, int connection_attempts,
294     int anonymous, uid_t original_real_uid,
295     const char *proxy_command);
296 
297 /*
298  * Starts a dialog with the server, and authenticates the current user on the
299  * server.  This does not need any extra privileges.  The basic connection to
300  * the server must already have been established before this is called. If
301  * login fails, this function prints an error and never returns. This
302  * initializes the random state, and leaves it initialized (it will also have
303  * references from the packet module).
304  */
305 
306 void
307 ssh_login(int host_key_valid, RSA * host_key, const char *host,
308     struct sockaddr * hostaddr, uid_t original_real_uid);
309 
310 /*------------ Definitions for various authentication methods. -------*/
311 
312 /*
313  * Tries to authenticate the user using the .rhosts file.  Returns true if
314  * authentication succeeds.  If ignore_rhosts is non-zero, this will not
315  * consider .rhosts and .shosts (/etc/hosts.equiv will still be used).
316  */
317 int     auth_rhosts(struct passwd * pw, const char *client_user);
318 
319 /*
320  * Tries to authenticate the user using the .rhosts file and the host using
321  * its host key.  Returns true if authentication succeeds.
322  */
323 int
324 auth_rhosts_rsa(struct passwd * pw, const char *client_user, RSA* client_host_key);
325 
326 /*
327  * Tries to authenticate the user using password.  Returns true if
328  * authentication succeeds.
329  */
330 int     auth_password(struct passwd * pw, const char *password);
331 
332 /*
333  * Performs the RSA authentication dialog with the client.  This returns 0 if
334  * the client could not be authenticated, and 1 if authentication was
335  * successful.  This may exit if there is a serious protocol violation.
336  */
337 int     auth_rsa(struct passwd * pw, BIGNUM * client_n);
338 
339 /*
340  * Parses an RSA key (number of bits, e, n) from a string.  Moves the pointer
341  * over the key.  Skips any whitespace at the beginning and at end.
342  */
343 int     auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n);
344 
345 /*
346  * Returns the name of the machine at the other end of the socket.  The
347  * returned string should be freed by the caller.
348  */
349 char   *get_remote_hostname(int socket);
350 
351 /*
352  * Return the canonical name of the host in the other side of the current
353  * connection (as returned by packet_get_connection).  The host name is
354  * cached, so it is efficient to call this several times.
355  */
356 const char *get_canonical_hostname(void);
357 
358 /*
359  * Returns the remote IP address as an ascii string.  The value need not be
360  * freed by the caller.
361  */
362 const char *get_remote_ipaddr(void);
363 
364 /* Returns the port number of the peer of the socket. */
365 int     get_peer_port(int sock);
366 
367 /* Returns the port number of the remote/local host. */
368 int     get_remote_port(void);
369 int	get_local_port(void);
370 
371 
372 /*
373  * Performs the RSA authentication challenge-response dialog with the client,
374  * and returns true (non-zero) if the client gave the correct answer to our
375  * challenge; returns zero if the client gives a wrong answer.
376  */
377 int     auth_rsa_challenge_dialog(RSA *pk);
378 
379 /*
380  * Reads a passphrase from /dev/tty with echo turned off.  Returns the
381  * passphrase (allocated with xmalloc).  Exits if EOF is encountered. If
382  * from_stdin is true, the passphrase will be read from stdin instead.
383  */
384 char   *read_passphrase(const char *prompt, int from_stdin);
385 
386 /*
387  * Saves the authentication (private) key in a file, encrypting it with
388  * passphrase.  The identification of the file (lowest 64 bits of n) will
389  * precede the key to provide identification of the key without needing a
390  * passphrase.
391  */
392 int
393 save_private_key(const char *filename, const char *passphrase,
394     RSA * private_key, const char *comment);
395 
396 /*
397  * Loads the public part of the key file (public key and comment). Returns 0
398  * if an error occurred; zero if the public key was successfully read.  The
399  * comment of the key is returned in comment_return if it is non-NULL; the
400  * caller must free the value with xfree.
401  */
402 int
403 load_public_key(const char *filename, RSA * pub,
404     char **comment_return);
405 
406 /*
407  * Loads the private key from the file.  Returns 0 if an error is encountered
408  * (file does not exist or is not readable, or passphrase is bad). This
409  * initializes the private key.  The comment of the key is returned in
410  * comment_return if it is non-NULL; the caller must free the value with
411  * xfree.
412  */
413 int
414 load_private_key(const char *filename, const char *passphrase,
415     RSA * private_key, char **comment_return);
416 
417 /*------------ Definitions for logging. -----------------------*/
418 
419 /* Supported syslog facilities and levels. */
420 typedef enum {
421 	SYSLOG_FACILITY_DAEMON,
422 	SYSLOG_FACILITY_USER,
423 	SYSLOG_FACILITY_AUTH,
424 	SYSLOG_FACILITY_LOCAL0,
425 	SYSLOG_FACILITY_LOCAL1,
426 	SYSLOG_FACILITY_LOCAL2,
427 	SYSLOG_FACILITY_LOCAL3,
428 	SYSLOG_FACILITY_LOCAL4,
429 	SYSLOG_FACILITY_LOCAL5,
430 	SYSLOG_FACILITY_LOCAL6,
431 	SYSLOG_FACILITY_LOCAL7
432 }       SyslogFacility;
433 
434 typedef enum {
435 	SYSLOG_LEVEL_QUIET,
436 	SYSLOG_LEVEL_FATAL,
437 	SYSLOG_LEVEL_ERROR,
438 	SYSLOG_LEVEL_INFO,
439 	SYSLOG_LEVEL_VERBOSE,
440 	SYSLOG_LEVEL_DEBUG
441 }       LogLevel;
442 /* Initializes logging. */
443 void    log_init(char *av0, LogLevel level, SyslogFacility facility, int on_stderr);
444 
445 /* Logging implementation, depending on server or client */
446 void    do_log(LogLevel level, const char *fmt, va_list args);
447 
448 /* name to facility/level */
449 SyslogFacility log_facility_number(char *name);
450 LogLevel log_level_number(char *name);
451 
452 /* Output a message to syslog or stderr */
453 void    fatal(const char *fmt,...) __attribute__((format(printf, 1, 2)));
454 void    error(const char *fmt,...) __attribute__((format(printf, 1, 2)));
455 void    log(const char *fmt,...) __attribute__((format(printf, 1, 2)));
456 void    verbose(const char *fmt,...) __attribute__((format(printf, 1, 2)));
457 void    debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));
458 
459 /* same as fatal() but w/o logging */
460 void    fatal_cleanup(void);
461 
462 /*
463  * Registers a cleanup function to be called by fatal()/fatal_cleanup()
464  * before exiting. It is permissible to call fatal_remove_cleanup for the
465  * function itself from the function.
466  */
467 void    fatal_add_cleanup(void (*proc) (void *context), void *context);
468 
469 /* Removes a cleanup function to be called at fatal(). */
470 void    fatal_remove_cleanup(void (*proc) (void *context), void *context);
471 
472 /*---------------- definitions for channels ------------------*/
473 
474 /* Sets specific protocol options. */
475 void    channel_set_options(int hostname_in_open);
476 
477 /*
478  * Allocate a new channel object and set its type and socket.  Remote_name
479  * must have been allocated with xmalloc; this will free it when the channel
480  * is freed.
481  */
482 int     channel_allocate(int type, int sock, char *remote_name);
483 
484 /* Free the channel and close its socket. */
485 void    channel_free(int channel);
486 
487 /* Add any bits relevant to channels in select bitmasks. */
488 void    channel_prepare_select(fd_set * readset, fd_set * writeset);
489 
490 /*
491  * After select, perform any appropriate operations for channels which have
492  * events pending.
493  */
494 void    channel_after_select(fd_set * readset, fd_set * writeset);
495 
496 /* If there is data to send to the connection, send some of it now. */
497 void    channel_output_poll(void);
498 
499 /*
500  * This is called when a packet of type CHANNEL_DATA has just been received.
501  * The message type has already been consumed, but channel number and data is
502  * still there.
503  */
504 void    channel_input_data(int payload_len);
505 
506 /* Returns true if no channel has too much buffered data. */
507 int     channel_not_very_much_buffered_data(void);
508 
509 /* This is called after receiving CHANNEL_CLOSE. */
510 void    channel_input_close(void);
511 
512 /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION. */
513 void    channel_input_close_confirmation(void);
514 
515 /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
516 void    channel_input_open_confirmation(void);
517 
518 /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
519 void    channel_input_open_failure(void);
520 
521 /* This closes any sockets that are listening for connections; this removes
522    any unix domain sockets. */
523 void    channel_stop_listening(void);
524 
525 /*
526  * Closes the sockets of all channels.  This is used to close extra file
527  * descriptors after a fork.
528  */
529 void    channel_close_all(void);
530 
531 /* Returns the maximum file descriptor number used by the channels. */
532 int     channel_max_fd(void);
533 
534 /* Returns true if there is still an open channel over the connection. */
535 int     channel_still_open(void);
536 
537 /*
538  * Returns a string containing a list of all open channels.  The list is
539  * suitable for displaying to the user.  It uses crlf instead of newlines.
540  * The caller should free the string with xfree.
541  */
542 char   *channel_open_message(void);
543 
544 /*
545  * Initiate forwarding of connections to local port "port" through the secure
546  * channel to host:port from remote side.  This never returns if there was an
547  * error.
548  */
549 void
550 channel_request_local_forwarding(u_short port, const char *host,
551     u_short remote_port, int gateway_ports);
552 
553 /*
554  * Initiate forwarding of connections to port "port" on remote host through
555  * the secure channel to host:port from local side.  This never returns if
556  * there was an error.  This registers that open requests for that port are
557  * permitted.
558  */
559 void
560 channel_request_remote_forwarding(u_short port, const char *host,
561     u_short remote_port);
562 
563 /*
564  * Permits opening to any host/port in SSH_MSG_PORT_OPEN.  This is usually
565  * called by the server, because the user could connect to any port anyway,
566  * and the server has no way to know but to trust the client anyway.
567  */
568 void    channel_permit_all_opens(void);
569 
570 /*
571  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
572  * listening for the port, and sends back a success reply (or disconnect
573  * message if there was an error).  This never returns if there was an error.
574  */
575 void    channel_input_port_forward_request(int is_root);
576 
577 /*
578  * This is called after receiving PORT_OPEN message.  This attempts to
579  * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
580  * or CHANNEL_OPEN_FAILURE.
581  */
582 void    channel_input_port_open(int payload_len);
583 
584 /*
585  * Creates a port for X11 connections, and starts listening for it. Returns
586  * the display name, or NULL if an error was encountered.
587  */
588 char   *x11_create_display(int screen);
589 
590 /*
591  * Creates an internet domain socket for listening for X11 connections.
592  * Returns a suitable value for the DISPLAY variable, or NULL if an error
593  * occurs.
594  */
595 char   *x11_create_display_inet(int screen, int x11_display_offset);
596 
597 /*
598  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
599  * the remote channel number.  We should do whatever we want, and respond
600  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
601  */
602 void    x11_input_open(int payload_len);
603 
604 /*
605  * Requests forwarding of X11 connections.  This should be called on the
606  * client only.
607  */
608 void    x11_request_forwarding(void);
609 
610 /*
611  * Requests forwarding for X11 connections, with authentication spoofing.
612  * This should be called in the client only.
613  */
614 void    x11_request_forwarding_with_spoofing(const char *proto, const char *data);
615 
616 /* Sends a message to the server to request authentication fd forwarding. */
617 void    auth_request_forwarding(void);
618 
619 /*
620  * Returns the name of the forwarded authentication socket.  Returns NULL if
621  * there is no forwarded authentication socket.  The returned value points to
622  * a static buffer.
623  */
624 char   *auth_get_socket_name(void);
625 
626 /*
627  * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
628  * This starts forwarding authentication requests.
629  */
630 void    auth_input_request_forwarding(struct passwd * pw);
631 
632 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
633 void    auth_input_open_request(void);
634 
635 /*
636  * Returns true if the given string matches the pattern (which may contain ?
637  * and * as wildcards), and zero if it does not match.
638  */
639 int     match_pattern(const char *s, const char *pattern);
640 
641 /*
642  * Expands tildes in the file name.  Returns data allocated by xmalloc.
643  * Warning: this calls getpw*.
644  */
645 char   *tilde_expand_filename(const char *filename, uid_t my_uid);
646 
647 /*
648  * Performs the interactive session.  This handles data transmission between
649  * the client and the program.  Note that the notion of stdin, stdout, and
650  * stderr in this function is sort of reversed: this function writes to stdin
651  * (of the child program), and reads from stdout and stderr (of the child
652  * program).
653  */
654 void    server_loop(int pid, int fdin, int fdout, int fderr);
655 
656 /* Client side main loop for the interactive session. */
657 int     client_loop(int have_pty, int escape_char);
658 
659 /* Linked list of custom environment strings (see auth-rsa.c). */
660 struct envstring {
661 	struct envstring *next;
662 	char   *s;
663 };
664 
665 /*
666  * Ensure all of data on socket comes through. f==read || f==write
667  */
668 ssize_t	atomicio(ssize_t (*f)(), int fd, void *s, size_t n);
669 
670 #ifdef KRB5
671 #include <krb5.h>
672 int	auth_krb5();  /* XXX Doplnit prototypy */
673 int	auth_krb5_tgt();
674 int	krb5_init();
675 void	krb5_cleanup_proc(void *ignore);
676 int	auth_krb5_password(struct passwd *pw, const char *password);
677 #endif /* KRB5 */
678 
679 #ifdef KRB4
680 #include <krb.h>
681 /*
682  * Performs Kerberos v4 mutual authentication with the client. This returns 0
683  * if the client could not be authenticated, and 1 if authentication was
684  * successful.  This may exit if there is a serious protocol violation.
685  */
686 int     auth_krb4(const char *server_user, KTEXT auth, char **client);
687 int     krb4_init(uid_t uid);
688 void    krb4_cleanup_proc(void *ignore);
689 int	auth_krb4_password(struct passwd * pw, const char *password);
690 
691 #ifdef AFS
692 #include <kafs.h>
693 
694 /* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */
695 int     auth_krb4_tgt(struct passwd * pw, const char *string);
696 int     auth_afs_token(struct passwd * pw, const char *token_string);
697 
698 int     creds_to_radix(CREDENTIALS * creds, unsigned char *buf);
699 int     radix_to_creds(const char *buf, CREDENTIALS * creds);
700 #endif				/* AFS */
701 
702 #endif				/* KRB4 */
703 
704 #ifdef SKEY
705 #include <skey.h>
706 char   *skey_fake_keyinfo(char *username);
707 int	auth_skey_password(struct passwd * pw, const char *password);
708 #endif				/* SKEY */
709 
710 /* AF_UNSPEC or AF_INET or AF_INET6 */
711 extern int IPv4or6;
712 
713 #endif				/* SSH_H */
714