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authorColin Watson <cjwatson@debian.org>2003-09-01 01:47:17 +0000
committerColin Watson <cjwatson@debian.org>2003-09-01 01:47:17 +0000
commit58657d96514cd6f16d82add8d6f4adbb36765758 (patch)
treeb618adf8cafe8afd07b90ea24120d986b1d67dee /ssh.0
parent1c992c4c13ea6c8fcd80093b340bc49753e17a4f (diff)
parentd984a3c6658e950881edcfb2aae464add93f68d4 (diff)
Import OpenSSH 3.5p1.
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1SSH(1) System General Commands Manual SSH(1)
2
3NAME
4 ssh - OpenSSH SSH client (remote login program)
5
6SYNOPSIS
7 ssh [-l login_name] hostname | user@hostname [command]
8
9 ssh [-afgknqstvxACNTX1246] [-b bind_address] [-c cipher_spec]
10 [-e escape_char] [-i identity_file] [-l login_name] [-m mac_spec]
11 [-o option] [-p port] [-F configfile] [-L port:host:hostport] [-R
12 port:host:hostport] [-D port] hostname | user@hostname [command]
13
14DESCRIPTION
15 ssh (SSH client) is a program for logging into a remote machine and for
16 executing commands on a remote machine. It is intended to replace rlogin
17 and rsh, and provide secure encrypted communications between two
18 untrusted hosts over an insecure network. X11 connections and arbitrary
19 TCP/IP ports can also be forwarded over the secure channel.
20
21 ssh connects and logs into the specified hostname. The user must prove
22 his/her identity to the remote machine using one of several methods
23 depending on the protocol version used:
24
25 SSH protocol version 1
26
27 First, if the machine the user logs in from is listed in /etc/hosts.equiv
28 or /etc/shosts.equiv on the remote machine, and the user names are the
29 same on both sides, the user is immediately permitted to log in. Second,
30 if .rhosts or .shosts exists in the user's home directory on the remote
31 machine and contains a line containing the name of the client machine and
32 the name of the user on that machine, the user is permitted to log in.
33 This form of authentication alone is normally not allowed by the server
34 because it is not secure.
35
36 The second authentication method is the rhosts or hosts.equiv method comM--
37 bined with RSA-based host authentication. It means that if the login
38 would be permitted by $HOME/.rhosts, $HOME/.shosts, /etc/hosts.equiv, or
39 /etc/shosts.equiv, and if additionally the server can verify the client's
40 host key (see /etc/ssh/ssh_known_hosts and $HOME/.ssh/known_hosts in the
41 FILES section), only then login is permitted. This authentication method
42 closes security holes due to IP spoofing, DNS spoofing and routing spoofM--
43 ing. [Note to the administrator: /etc/hosts.equiv, $HOME/.rhosts, and
44 the rlogin/rsh protocol in general, are inherently insecure and should be
45 disabled if security is desired.]
46
47 As a third authentication method, ssh supports RSA based authentication.
48 The scheme is based on public-key cryptography: there are cryptosystems
49 where encryption and decryption are done using separate keys, and it is
50 not possible to derive the decryption key from the encryption key. RSA
51 is one such system. The idea is that each user creates a public/private
52 key pair for authentication purposes. The server knows the public key,
53 and only the user knows the private key. The file
54 $HOME/.ssh/authorized_keys lists the public keys that are permitted for
55 logging in. When the user logs in, the ssh program tells the server
56 which key pair it would like to use for authentication. The server
57 checks if this key is permitted, and if so, sends the user (actually the
58 ssh program running on behalf of the user) a challenge, a random number,
59 encrypted by the user's public key. The challenge can only be decrypted
60 using the proper private key. The user's client then decrypts the chalM--
61 lenge using the private key, proving that he/she knows the private key
62 but without disclosing it to the server.
63
64 ssh implements the RSA authentication protocol automatically. The user
65 creates his/her RSA key pair by running ssh-keygen(1). This stores the
66 private key in $HOME/.ssh/identity and the public key in
67 $HOME/.ssh/identity.pub in the user's home directory. The user should
68 then copy the identity.pub to $HOME/.ssh/authorized_keys in his/her home
69 directory on the remote machine (the authorized_keys file corresponds to
70 the conventional $HOME/.rhosts file, and has one key per line, though the
71 lines can be very long). After this, the user can log in without giving
72 the password. RSA authentication is much more secure than rhosts authenM--
73 tication.
74
75 The most convenient way to use RSA authentication may be with an authenM--
76 tication agent. See ssh-agent(1) for more information.
77
78 If other authentication methods fail, ssh prompts the user for a passM--
79 word. The password is sent to the remote host for checking; however,
80 since all communications are encrypted, the password cannot be seen by
81 someone listening on the network.
82
83 SSH protocol version 2
84
85 When a user connects using protocol version 2 similar authentication
86 methods are available. Using the default values for
87 PreferredAuthentications, the client will try to authenticate first using
88 the hostbased method; if this method fails public key authentication is
89 attempted, and finally if this method fails keyboard-interactive and
90 password authentication are tried.
91
92 The public key method is similar to RSA authentication described in the
93 previous section and allows the RSA or DSA algorithm to be used: The
94 client uses his private key, $HOME/.ssh/id_dsa or $HOME/.ssh/id_rsa, to
95 sign the session identifier and sends the result to the server. The
96 server checks whether the matching public key is listed in
97 $HOME/.ssh/authorized_keys and grants access if both the key is found and
98 the signature is correct. The session identifier is derived from a
99 shared Diffie-Hellman value and is only known to the client and the
100 server.
101
102 If public key authentication fails or is not available a password can be
103 sent encrypted to the remote host for proving the user's identity.
104
105 Additionally, ssh supports hostbased or challenge response authenticaM--
106 tion.
107
108 Protocol 2 provides additional mechanisms for confidentiality (the trafM--
109 fic is encrypted using 3DES, Blowfish, CAST128 or Arcfour) and integrity
110 (hmac-md5, hmac-sha1). Note that protocol 1 lacks a strong mechanism for
111 ensuring the integrity of the connection.
112
113 Login session and remote execution
114
115 When the user's identity has been accepted by the server, the server
116 either executes the given command, or logs into the machine and gives the
117 user a normal shell on the remote machine. All communication with the
118 remote command or shell will be automatically encrypted.
119
120 If a pseudo-terminal has been allocated (normal login session), the user
121 may use the escape characters noted below.
122
123 If no pseudo tty has been allocated, the session is transparent and can
124 be used to reliably transfer binary data. On most systems, setting the
125 escape character to ``none'' will also make the session transparent even
126 if a tty is used.
127
128 The session terminates when the command or shell on the remote machine
129 exits and all X11 and TCP/IP connections have been closed. The exit staM--
130 tus of the remote program is returned as the exit status of ssh.
131
132 Escape Characters
133
134 When a pseudo terminal has been requested, ssh supports a number of funcM--
135 tions through the use of an escape character.
136
137 A single tilde character can be sent as ~~ or by following the tilde by a
138 character other than those described below. The escape character must
139 always follow a newline to be interpreted as special. The escape characM--
140 ter can be changed in configuration files using the EscapeChar configuraM--
141 tion directive or on the command line by the -e option.
142
143 The supported escapes (assuming the default `~') are:
144
145 ~. Disconnect
146
147 ~^Z Background ssh
148
149 ~# List forwarded connections
150
151 ~& Background ssh at logout when waiting for forwarded connection /
152 X11 sessions to terminate
153
154 ~? Display a list of escape characters
155
156 ~C Open command line (only useful for adding port forwardings using
157 the -L and -R options)
158
159 ~R Request rekeying of the connection (only useful for SSH protocol
160 version 2 and if the peer supports it)
161
162 X11 and TCP forwarding
163
164 If the ForwardX11 variable is set to ``yes'' (or, see the description of
165 the -X and -x options described later) and the user is using X11 (the
166 DISPLAY environment variable is set), the connection to the X11 display
167 is automatically forwarded to the remote side in such a way that any X11
168 programs started from the shell (or command) will go through the
169 encrypted channel, and the connection to the real X server will be made
170 from the local machine. The user should not manually set DISPLAY. ForM--
171 warding of X11 connections can be configured on the command line or in
172 configuration files.
173
174 The DISPLAY value set by ssh will point to the server machine, but with a
175 display number greater than zero. This is normal, and happens because
176 ssh creates a ``proxy'' X server on the server machine for forwarding the
177 connections over the encrypted channel.
178
179 ssh will also automatically set up Xauthority data on the server machine.
180 For this purpose, it will generate a random authorization cookie, store
181 it in Xauthority on the server, and verify that any forwarded connections
182 carry this cookie and replace it by the real cookie when the connection
183 is opened. The real authentication cookie is never sent to the server
184 machine (and no cookies are sent in the plain).
185
186 If the ForwardAgent variable is set to ``yes'' (or, see the description
187 of the -A and -a options described later) and the user is using an
188 authentication agent, the connection to the agent is automatically forM--
189 warded to the remote side.
190
191 Forwarding of arbitrary TCP/IP connections over the secure channel can be
192 specified either on the command line or in a configuration file. One
193 possible application of TCP/IP forwarding is a secure connection to an
194 electronic purse; another is going through firewalls.
195
196 Server authentication
197
198 ssh automatically maintains and checks a database containing identificaM--
199 tions for all hosts it has ever been used with. Host keys are stored in
200 $HOME/.ssh/known_hosts in the user's home directory. Additionally, the
201 file /etc/ssh/ssh_known_hosts is automatically checked for known hosts.
202 Any new hosts are automatically added to the user's file. If a host's
203 identification ever changes, ssh warns about this and disables password
204 authentication to prevent a trojan horse from getting the user's passM--
205 word. Another purpose of this mechanism is to prevent man-in-the-middle
206 attacks which could otherwise be used to circumvent the encryption. The
207 StrictHostKeyChecking option can be used to prevent logins to machines
208 whose host key is not known or has changed.
209
210 The options are as follows:
211
212 -a Disables forwarding of the authentication agent connection.
213
214 -A Enables forwarding of the authentication agent connection. This
215 can also be specified on a per-host basis in a configuration
216 file.
217
218 Agent forwarding should be enabled with caution. Users with the
219 ability to bypass file permissions on the remote host (for the
220 agent's Unix-domain socket) can access the local agent through
221 the forwarded connection. An attacker cannot obtain key material
222 from the agent, however they can perform operations on the keys
223 that enable them to authenticate using the identities loaded into
224 the agent.
225
226 -b bind_address
227 Specify the interface to transmit from on machines with multiple
228 interfaces or aliased addresses.
229
230 -c blowfish|3des|des
231 Selects the cipher to use for encrypting the session. 3des is
232 used by default. It is believed to be secure. 3des (triple-des)
233 is an encrypt-decrypt-encrypt triple with three different keys.
234 blowfish is a fast block cipher, it appears very secure and is
235 much faster than 3des. des is only supported in the ssh client
236 for interoperability with legacy protocol 1 implementations that
237 do not support the 3des cipher. Its use is strongly discouraged
238 due to cryptographic weaknesses.
239
240 -c cipher_spec
241 Additionally, for protocol version 2 a comma-separated list of
242 ciphers can be specified in order of preference. See Ciphers for
243 more information.
244
245 -e ch|^ch|none
246 Sets the escape character for sessions with a pty (default: `~').
247 The escape character is only recognized at the beginning of a
248 line. The escape character followed by a dot (`.') closes the
249 connection, followed by control-Z suspends the connection, and
250 followed by itself sends the escape character once. Setting the
251 character to ``none'' disables any escapes and makes the session
252 fully transparent.
253
254 -f Requests ssh to go to background just before command execution.
255 This is useful if ssh is going to ask for passwords or
256 passphrases, but the user wants it in the background. This
257 implies -n. The recommended way to start X11 programs at a
258 remote site is with something like ssh -f host xterm.
259
260 -g Allows remote hosts to connect to local forwarded ports.
261
262 -i identity_file
263 Selects a file from which the identity (private key) for RSA or
264 DSA authentication is read. The default is $HOME/.ssh/identity
265 for protocol version 1, and $HOME/.ssh/id_rsa and
266 $HOME/.ssh/id_dsa for protocol version 2. Identity files may
267 also be specified on a per-host basis in the configuration file.
268 It is possible to have multiple -i options (and multiple identiM--
269 ties specified in configuration files).
270
271 -I smartcard_device
272 Specifies which smartcard device to use. The argument is the
273 device ssh should use to communicate with a smartcard used for
274 storing the user's private RSA key.
275
276 -k Disables forwarding of Kerberos tickets and AFS tokens. This may
277 also be specified on a per-host basis in the configuration file.
278
279 -l login_name
280 Specifies the user to log in as on the remote machine. This also
281 may be specified on a per-host basis in the configuration file.
282
283 -m mac_spec
284 Additionally, for protocol version 2 a comma-separated list of
285 MAC (message authentication code) algorithms can be specified in
286 order of preference. See the MACs keyword for more information.
287
288 -n Redirects stdin from /dev/null (actually, prevents reading from
289 stdin). This must be used when ssh is run in the background. A
290 common trick is to use this to run X11 programs on a remote
291 machine. For example, ssh -n shadows.cs.hut.fi emacs & will
292 start an emacs on shadows.cs.hut.fi, and the X11 connection will
293 be automatically forwarded over an encrypted channel. The ssh
294 program will be put in the background. (This does not work if
295 ssh needs to ask for a password or passphrase; see also the -f
296 option.)
297
298 -N Do not execute a remote command. This is useful for just forM--
299 warding ports (protocol version 2 only).
300
301 -o option
302 Can be used to give options in the format used in the configuraM--
303 tion file. This is useful for specifying options for which there
304 is no separate command-line flag.
305
306 -p port
307 Port to connect to on the remote host. This can be specified on
308 a per-host basis in the configuration file.
309
310 -q Quiet mode. Causes all warning and diagnostic messages to be
311 suppressed.
312
313 -s May be used to request invocation of a subsystem on the remote
314 system. Subsystems are a feature of the SSH2 protocol which
315 facilitate the use of SSH as a secure transport for other appliM--
316 cations (eg. sftp). The subsystem is specified as the remote comM--
317 mand.
318
319 -t Force pseudo-tty allocation. This can be used to execute arbiM--
320 trary screen-based programs on a remote machine, which can be
321 very useful, e.g., when implementing menu services. Multiple -t
322 options force tty allocation, even if ssh has no local tty.
323
324 -T Disable pseudo-tty allocation.
325
326 -v Verbose mode. Causes ssh to print debugging messages about its
327 progress. This is helpful in debugging connection, authenticaM--
328 tion, and configuration problems. Multiple -v options increases
329 the verbosity. Maximum is 3.
330
331 -x Disables X11 forwarding.
332
333 -X Enables X11 forwarding. This can also be specified on a per-host
334 basis in a configuration file.
335
336 X11 forwarding should be enabled with caution. Users with the
337 ability to bypass file permissions on the remote host (for the
338 user's X authorization database) can access the local X11 display
339 through the forwarded connection. An attacker may then be able
340 to perform activities such as keystroke monitoring.
341
342 -C Requests compression of all data (including stdin, stdout,
343 stderr, and data for forwarded X11 and TCP/IP connections). The
344 compression algorithm is the same used by gzip(1), and the
345 ``level'' can be controlled by the CompressionLevel option for
346 protocol version 1. Compression is desirable on modem lines and
347 other slow connections, but will only slow down things on fast
348 networks. The default value can be set on a host-by-host basis
349 in the configuration files; see the Compression option.
350
351 -F configfile
352 Specifies an alternative per-user configuration file. If a conM--
353 figuration file is given on the command line, the system-wide
354 configuration file (/etc/ssh/ssh_config) will be ignored. The
355 default for the per-user configuration file is $HOME/.ssh/config.
356
357 -L port:host:hostport
358 Specifies that the given port on the local (client) host is to be
359 forwarded to the given host and port on the remote side. This
360 works by allocating a socket to listen to port on the local side,
361 and whenever a connection is made to this port, the connection is
362 forwarded over the secure channel, and a connection is made to
363 host port hostport from the remote machine. Port forwardings can
364 also be specified in the configuration file. Only root can forM--
365 ward privileged ports. IPv6 addresses can be specified with an
366 alternative syntax: port/host/hostport
367
368 -R port:host:hostport
369 Specifies that the given port on the remote (server) host is to
370 be forwarded to the given host and port on the local side. This
371 works by allocating a socket to listen to port on the remote
372 side, and whenever a connection is made to this port, the connecM--
373 tion is forwarded over the secure channel, and a connection is
374 made to host port hostport from the local machine. Port forwardM--
375 ings can also be specified in the configuration file. Privileged
376 ports can be forwarded only when logging in as root on the remote
377 machine. IPv6 addresses can be specified with an alternative
378 syntax: port/host/hostport
379
380 -D port
381 Specifies a local ``dynamic'' application-level port forwarding.
382 This works by allocating a socket to listen to port on the local
383 side, and whenever a connection is made to this port, the connecM--
384 tion is forwarded over the secure channel, and the application
385 protocol is then used to determine where to connect to from the
386 remote machine. Currently the SOCKS4 protocol is supported, and
387 ssh will act as a SOCKS4 server. Only root can forward priviM--
388 leged ports. Dynamic port forwardings can also be specified in
389 the configuration file.
390
391 -1 Forces ssh to try protocol version 1 only.
392
393 -2 Forces ssh to try protocol version 2 only.
394
395 -4 Forces ssh to use IPv4 addresses only.
396
397 -6 Forces ssh to use IPv6 addresses only.
398
399CONFIGURATION FILES
400 ssh may additionally obtain configuration data from a per-user configuraM--
401 tion file and a system-wide configuration file. The file format and conM--
402 figuration options are described in ssh_config(5).
403
404ENVIRONMENT
405 ssh will normally set the following environment variables:
406
407 DISPLAY
408 The DISPLAY variable indicates the location of the X11 server.
409 It is automatically set by ssh to point to a value of the form
410 ``hostname:n'' where hostname indicates the host where the shell
411 runs, and n is an integer >= 1. ssh uses this special value to
412 forward X11 connections over the secure channel. The user should
413 normally not set DISPLAY explicitly, as that will render the X11
414 connection insecure (and will require the user to manually copy
415 any required authorization cookies).
416
417 HOME Set to the path of the user's home directory.
418
419 LOGNAME
420 Synonym for USER; set for compatibility with systems that use
421 this variable.
422
423 MAIL Set to the path of the user's mailbox.
424
425 PATH Set to the default PATH, as specified when compiling ssh.
426
427 SSH_ASKPASS
428 If ssh needs a passphrase, it will read the passphrase from the
429 current terminal if it was run from a terminal. If ssh does not
430 have a terminal associated with it but DISPLAY and SSH_ASKPASS
431 are set, it will execute the program specified by SSH_ASKPASS and
432 open an X11 window to read the passphrase. This is particularly
433 useful when calling ssh from a .Xsession or related script.
434 (Note that on some machines it may be necessary to redirect the
435 input from /dev/null to make this work.)
436
437 SSH_AUTH_SOCK
438 Identifies the path of a unix-domain socket used to communicate
439 with the agent.
440
441 SSH_CONNECTION
442 Identifies the client and server ends of the connection. The
443 variable contains four space-separated values: client ip-address,
444 client port number, server ip-address and server port number.
445
446 SSH_ORIGINAL_COMMAND
447 The variable contains the original command line if a forced comM--
448 mand is executed. It can be used to extract the original arguM--
449 ments.
450
451 SSH_TTY
452 This is set to the name of the tty (path to the device) associM--
453 ated with the current shell or command. If the current session
454 has no tty, this variable is not set.
455
456 TZ The timezone variable is set to indicate the present timezone if
457 it was set when the daemon was started (i.e., the daemon passes
458 the value on to new connections).
459
460 USER Set to the name of the user logging in.
461
462 Additionally, ssh reads $HOME/.ssh/environment, and adds lines of the
463 format ``VARNAME=value'' to the environment if the file exists and if
464 users are allowed to change their environment. See the
465 PermitUserEnvironment option in sshd_config(5).
466
467FILES
468 $HOME/.ssh/known_hosts
469 Records host keys for all hosts the user has logged into that are
470 not in /etc/ssh/ssh_known_hosts. See sshd(8).
471
472 $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
473 Contains the authentication identity of the user. They are for
474 protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
475 These files contain sensitive data and should be readable by the
476 user but not accessible by others (read/write/execute). Note
477 that ssh ignores a private key file if it is accessible by othM--
478 ers. It is possible to specify a passphrase when generating the
479 key; the passphrase will be used to encrypt the sensitive part of
480 this file using 3DES.
481
482 $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
483 Contains the public key for authentication (public part of the
484 identity file in human-readable form). The contents of the
485 $HOME/.ssh/identity.pub file should be added to
486 $HOME/.ssh/authorized_keys on all machines where the user wishes
487 to log in using protocol version 1 RSA authentication. The conM--
488 tents of the $HOME/.ssh/id_dsa.pub and $HOME/.ssh/id_rsa.pub file
489 should be added to $HOME/.ssh/authorized_keys on all machines
490 where the user wishes to log in using protocol version 2 DSA/RSA
491 authentication. These files are not sensitive and can (but need
492 not) be readable by anyone. These files are never used automatiM--
493 cally and are not necessary; they are only provided for the conM--
494 venience of the user.
495
496 $HOME/.ssh/config
497 This is the per-user configuration file. The file format and
498 configuration options are described in ssh_config(5).
499
500 $HOME/.ssh/authorized_keys
501 Lists the public keys (RSA/DSA) that can be used for logging in
502 as this user. The format of this file is described in the
503 sshd(8) manual page. In the simplest form the format is the same
504 as the .pub identity files. This file is not highly sensitive,
505 but the recommended permissions are read/write for the user, and
506 not accessible by others.
507
508 /etc/ssh/ssh_known_hosts
509 Systemwide list of known host keys. This file should be prepared
510 by the system administrator to contain the public host keys of
511 all machines in the organization. This file should be world-
512 readable. This file contains public keys, one per line, in the
513 following format (fields separated by spaces): system name, pubM--
514 lic key and optional comment field. When different names are
515 used for the same machine, all such names should be listed, sepaM--
516 rated by commas. The format is described on the sshd(8) manual
517 page.
518
519 The canonical system name (as returned by name servers) is used
520 by sshd(8) to verify the client host when logging in; other names
521 are needed because ssh does not convert the user-supplied name to
522 a canonical name before checking the key, because someone with
523 access to the name servers would then be able to fool host
524 authentication.
525
526 /etc/ssh/ssh_config
527 Systemwide configuration file. The file format and configuration
528 options are described in ssh_config(5).
529
530 /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key,
531 /etc/ssh/ssh_host_rsa_key
532 These three files contain the private parts of the host keys and
533 are used for RhostsRSAAuthentication and HostbasedAuthentication.
534 If the protocol version 1 RhostsRSAAuthentication method is used,
535 ssh must be setuid root, since the host key is readable only by
536 root. For protocol version 2, ssh uses ssh-keysign(8) to access
537 the host keys for HostbasedAuthentication. This eliminates the
538 requirement that ssh be setuid root when that authentication
539 method is used. By default ssh is not setuid root.
540
541 $HOME/.rhosts
542 This file is used in .rhosts authentication to list the host/user
543 pairs that are permitted to log in. (Note that this file is also
544 used by rlogin and rsh, which makes using this file insecure.)
545 Each line of the file contains a host name (in the canonical form
546 returned by name servers), and then a user name on that host,
547 separated by a space. On some machines this file may need to be
548 world-readable if the user's home directory is on a NFS partiM--
549 tion, because sshd(8) reads it as root. Additionally, this file
550 must be owned by the user, and must not have write permissions
551 for anyone else. The recommended permission for most machines is
552 read/write for the user, and not accessible by others.
553
554 Note that by default sshd(8) will be installed so that it
555 requires successful RSA host authentication before permitting
556 .rhosts authentication. If the server machine does not have the
557 client's host key in /etc/ssh/ssh_known_hosts, it can be stored
558 in $HOME/.ssh/known_hosts. The easiest way to do this is to conM--
559 nect back to the client from the server machine using ssh; this
560 will automatically add the host key to $HOME/.ssh/known_hosts.
561
562 $HOME/.shosts
563 This file is used exactly the same way as .rhosts. The purpose
564 for having this file is to be able to use rhosts authentication
565 with ssh without permitting login with rlogin or rsh(1).
566
567 /etc/hosts.equiv
568 This file is used during .rhosts authentication. It contains
569 canonical hosts names, one per line (the full format is described
570 on the sshd(8) manual page). If the client host is found in this
571 file, login is automatically permitted provided client and server
572 user names are the same. Additionally, successful RSA host
573 authentication is normally required. This file should only be
574 writable by root.
575
576 /etc/shosts.equiv
577 This file is processed exactly as /etc/hosts.equiv. This file
578 may be useful to permit logins using ssh but not using
579 rsh/rlogin.
580
581 /etc/ssh/sshrc
582 Commands in this file are executed by ssh when the user logs in
583 just before the user's shell (or command) is started. See the
584 sshd(8) manual page for more information.
585
586 $HOME/.ssh/rc
587 Commands in this file are executed by ssh when the user logs in
588 just before the user's shell (or command) is started. See the
589 sshd(8) manual page for more information.
590
591 $HOME/.ssh/environment
592 Contains additional definitions for environment variables, see
593 section ENVIRONMENT above.
594
595DIAGNOSTICS
596 ssh exits with the exit status of the remote command or with 255 if an
597 error occurred.
598
599AUTHORS
600 OpenSSH is a derivative of the original and free ssh 1.2.12 release by
601 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
602 de Raadt and Dug Song removed many bugs, re-added newer features and creM--
603 ated OpenSSH. Markus Friedl contributed the support for SSH protocol
604 versions 1.5 and 2.0.
605
606SEE ALSO
607 rsh(1), scp(1), sftp(1), ssh-add(1), ssh-agent(1), ssh-keygen(1),
608 telnet(1), ssh_config(5), ssh-keysign(8), sshd(8)
609
610 T. Ylonen, T. Kivinen, M. Saarinen, T. Rinne, and S. Lehtinen, SSH
611 Protocol Architecture, draft-ietf-secsh-architecture-12.txt, January
612 2002, work in progress material.
613
614BSD September 25, 1999 BSD