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3c0ef626 | 1 | .\" -*- nroff -*- |
2 | .\" | |
3 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | .\" All rights reserved | |
6 | .\" | |
7 | .\" As far as I am concerned, the code I have written for this software | |
8 | .\" can be used freely for any purpose. Any derived versions of this | |
9 | .\" software must be clearly marked as such, and if the derived work is | |
10 | .\" incompatible with the protocol description in the RFC file, it must be | |
11 | .\" called by a name other than "ssh" or "Secure Shell". | |
12 | .\" | |
13 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. | |
14 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. | |
15 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. | |
16 | .\" | |
17 | .\" Redistribution and use in source and binary forms, with or without | |
18 | .\" modification, are permitted provided that the following conditions | |
19 | .\" are met: | |
20 | .\" 1. Redistributions of source code must retain the above copyright | |
21 | .\" notice, this list of conditions and the following disclaimer. | |
22 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
23 | .\" notice, this list of conditions and the following disclaimer in the | |
24 | .\" documentation and/or other materials provided with the distribution. | |
25 | .\" | |
26 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
27 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
28 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
29 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
30 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
31 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
32 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
33 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
34 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
35 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
36 | .\" | |
7e82606e | 37 | .\" $OpenBSD: ssh.1,v 1.194 2004/08/12 21:41:13 jakob Exp $ |
3c0ef626 | 38 | .Dd September 25, 1999 |
39 | .Dt SSH 1 | |
40 | .Os | |
41 | .Sh NAME | |
42 | .Nm ssh | |
43 | .Nd OpenSSH SSH client (remote login program) | |
44 | .Sh SYNOPSIS | |
45 | .Nm ssh | |
7e82606e | 46 | .Op Fl 1246AaCfgkMNnqsTtVvXxY |
3c0ef626 | 47 | .Op Fl b Ar bind_address |
48 | .Op Fl c Ar cipher_spec | |
7e82606e | 49 | .Bk -words |
540d72c3 | 50 | .Op Fl D Ar port |
3c0ef626 | 51 | .Op Fl e Ar escape_char |
3c0ef626 | 52 | .Op Fl F Ar configfile |
540d72c3 | 53 | .Op Fl i Ar identity_file |
3c0ef626 | 54 | .Oo Fl L Xo |
55 | .Sm off | |
56 | .Ar port : | |
57 | .Ar host : | |
58 | .Ar hostport | |
59 | .Sm on | |
60 | .Xc | |
61 | .Oc | |
bfe49944 | 62 | .Ek |
540d72c3 | 63 | .Op Fl l Ar login_name |
64 | .Op Fl m Ar mac_spec | |
65 | .Op Fl o Ar option | |
bfe49944 | 66 | .Bk -words |
540d72c3 | 67 | .Op Fl p Ar port |
68 | .Ek | |
3c0ef626 | 69 | .Oo Fl R Xo |
70 | .Sm off | |
71 | .Ar port : | |
72 | .Ar host : | |
73 | .Ar hostport | |
74 | .Sm on | |
75 | .Xc | |
76 | .Oc | |
7e82606e | 77 | .Op Fl S Ar ctl |
540d72c3 | 78 | .Oo Ar user Ns @ Oc Ns Ar hostname |
3c0ef626 | 79 | .Op Ar command |
80 | .Sh DESCRIPTION | |
81 | .Nm | |
82 | (SSH client) is a program for logging into a remote machine and for | |
83 | executing commands on a remote machine. | |
540d72c3 | 84 | It is intended to replace rlogin and rsh, |
85 | and provide secure encrypted communications between | |
3c0ef626 | 86 | two untrusted hosts over an insecure network. |
540d72c3 | 87 | X11 connections and arbitrary TCP/IP ports |
88 | can also be forwarded over the secure channel. | |
3c0ef626 | 89 | .Pp |
90 | .Nm | |
91 | connects and logs into the specified | |
540d72c3 | 92 | .Ar hostname |
93 | (with optional | |
94 | .Ar user | |
95 | name). | |
3c0ef626 | 96 | The user must prove |
97 | his/her identity to the remote machine using one of several methods | |
540d72c3 | 98 | depending on the protocol version used. |
3c0ef626 | 99 | .Pp |
540d72c3 | 100 | If |
101 | .Ar command | |
102 | is specified, | |
103 | .Ar command | |
104 | is executed on the remote host instead of a login shell. | |
3c0ef626 | 105 | .Ss SSH protocol version 1 |
3c0ef626 | 106 | First, if the machine the user logs in from is listed in |
107 | .Pa /etc/hosts.equiv | |
108 | or | |
109 | .Pa /etc/shosts.equiv | |
110 | on the remote machine, and the user names are | |
111 | the same on both sides, the user is immediately permitted to log in. | |
112 | Second, if | |
540d72c3 | 113 | .Pa .rhosts |
3c0ef626 | 114 | or |
540d72c3 | 115 | .Pa .shosts |
3c0ef626 | 116 | exists in the user's home directory on the |
117 | remote machine and contains a line containing the name of the client | |
118 | machine and the name of the user on that machine, the user is | |
119 | permitted to log in. | |
120 | This form of authentication alone is normally not | |
121 | allowed by the server because it is not secure. | |
122 | .Pp | |
123 | The second authentication method is the | |
540d72c3 | 124 | .Em rhosts |
3c0ef626 | 125 | or |
540d72c3 | 126 | .Em hosts.equiv |
3c0ef626 | 127 | method combined with RSA-based host authentication. |
128 | It means that if the login would be permitted by | |
129 | .Pa $HOME/.rhosts , | |
130 | .Pa $HOME/.shosts , | |
131 | .Pa /etc/hosts.equiv , | |
132 | or | |
133 | .Pa /etc/shosts.equiv , | |
134 | and if additionally the server can verify the client's | |
135 | host key (see | |
db32a221 | 136 | .Pa /etc/ssh/ssh_known_hosts |
3c0ef626 | 137 | and |
138 | .Pa $HOME/.ssh/known_hosts | |
139 | in the | |
140 | .Sx FILES | |
540d72c3 | 141 | section), only then is login permitted. |
3c0ef626 | 142 | This authentication method closes security holes due to IP |
143 | spoofing, DNS spoofing and routing spoofing. | |
144 | [Note to the administrator: | |
145 | .Pa /etc/hosts.equiv , | |
146 | .Pa $HOME/.rhosts , | |
147 | and the rlogin/rsh protocol in general, are inherently insecure and should be | |
148 | disabled if security is desired.] | |
149 | .Pp | |
150 | As a third authentication method, | |
151 | .Nm | |
152 | supports RSA based authentication. | |
153 | The scheme is based on public-key cryptography: there are cryptosystems | |
154 | where encryption and decryption are done using separate keys, and it | |
155 | is not possible to derive the decryption key from the encryption key. | |
156 | RSA is one such system. | |
157 | The idea is that each user creates a public/private | |
158 | key pair for authentication purposes. | |
159 | The server knows the public key, and only the user knows the private key. | |
540d72c3 | 160 | .Pp |
3c0ef626 | 161 | The file |
162 | .Pa $HOME/.ssh/authorized_keys | |
540d72c3 | 163 | lists the public keys that are permitted for logging in. |
3c0ef626 | 164 | When the user logs in, the |
165 | .Nm | |
166 | program tells the server which key pair it would like to use for | |
167 | authentication. | |
540d72c3 | 168 | The server checks if this key is permitted, and if so, |
169 | sends the user (actually the | |
3c0ef626 | 170 | .Nm |
171 | program running on behalf of the user) a challenge, a random number, | |
172 | encrypted by the user's public key. | |
540d72c3 | 173 | The challenge can only be decrypted using the proper private key. |
174 | The user's client then decrypts the challenge using the private key, | |
175 | proving that he/she knows the private key | |
176 | but without disclosing it to the server. | |
3c0ef626 | 177 | .Pp |
178 | .Nm | |
179 | implements the RSA authentication protocol automatically. | |
180 | The user creates his/her RSA key pair by running | |
181 | .Xr ssh-keygen 1 . | |
182 | This stores the private key in | |
183 | .Pa $HOME/.ssh/identity | |
540d72c3 | 184 | and stores the public key in |
3c0ef626 | 185 | .Pa $HOME/.ssh/identity.pub |
186 | in the user's home directory. | |
187 | The user should then copy the | |
188 | .Pa identity.pub | |
189 | to | |
190 | .Pa $HOME/.ssh/authorized_keys | |
191 | in his/her home directory on the remote machine (the | |
192 | .Pa authorized_keys | |
193 | file corresponds to the conventional | |
194 | .Pa $HOME/.rhosts | |
195 | file, and has one key | |
196 | per line, though the lines can be very long). | |
197 | After this, the user can log in without giving the password. | |
540d72c3 | 198 | RSA authentication is much more secure than |
199 | .Em rhosts | |
200 | authentication. | |
3c0ef626 | 201 | .Pp |
202 | The most convenient way to use RSA authentication may be with an | |
203 | authentication agent. | |
204 | See | |
205 | .Xr ssh-agent 1 | |
206 | for more information. | |
207 | .Pp | |
208 | If other authentication methods fail, | |
209 | .Nm | |
210 | prompts the user for a password. | |
211 | The password is sent to the remote | |
212 | host for checking; however, since all communications are encrypted, | |
213 | the password cannot be seen by someone listening on the network. | |
3c0ef626 | 214 | .Ss SSH protocol version 2 |
540d72c3 | 215 | When a user connects using protocol version 2, |
db32a221 | 216 | similar authentication methods are available. |
3c0ef626 | 217 | Using the default values for |
218 | .Cm PreferredAuthentications , | |
219 | the client will try to authenticate first using the hostbased method; | |
540d72c3 | 220 | if this method fails, public key authentication is attempted, |
221 | and finally if this method fails, keyboard-interactive and | |
3c0ef626 | 222 | password authentication are tried. |
223 | .Pp | |
224 | The public key method is similar to RSA authentication described | |
225 | in the previous section and allows the RSA or DSA algorithm to be used: | |
226 | The client uses his private key, | |
227 | .Pa $HOME/.ssh/id_dsa | |
228 | or | |
229 | .Pa $HOME/.ssh/id_rsa , | |
230 | to sign the session identifier and sends the result to the server. | |
231 | The server checks whether the matching public key is listed in | |
232 | .Pa $HOME/.ssh/authorized_keys | |
233 | and grants access if both the key is found and the signature is correct. | |
234 | The session identifier is derived from a shared Diffie-Hellman value | |
235 | and is only known to the client and the server. | |
236 | .Pp | |
540d72c3 | 237 | If public key authentication fails or is not available, a password |
238 | can be sent encrypted to the remote host to prove the user's identity. | |
3c0ef626 | 239 | .Pp |
240 | Additionally, | |
241 | .Nm | |
242 | supports hostbased or challenge response authentication. | |
243 | .Pp | |
244 | Protocol 2 provides additional mechanisms for confidentiality | |
7e82606e | 245 | (the traffic is encrypted using AES, 3DES, Blowfish, CAST128 or Arcfour) |
246 | and integrity (hmac-md5, hmac-sha1, hmac-ripemd160). | |
3c0ef626 | 247 | Note that protocol 1 lacks a strong mechanism for ensuring the |
248 | integrity of the connection. | |
3c0ef626 | 249 | .Ss Login session and remote execution |
3c0ef626 | 250 | When the user's identity has been accepted by the server, the server |
251 | either executes the given command, or logs into the machine and gives | |
252 | the user a normal shell on the remote machine. | |
253 | All communication with | |
254 | the remote command or shell will be automatically encrypted. | |
255 | .Pp | |
256 | If a pseudo-terminal has been allocated (normal login session), the | |
257 | user may use the escape characters noted below. | |
258 | .Pp | |
540d72c3 | 259 | If no pseudo-tty has been allocated, |
260 | the session is transparent and can be used to reliably transfer binary data. | |
3c0ef626 | 261 | On most systems, setting the escape character to |
262 | .Dq none | |
263 | will also make the session transparent even if a tty is used. | |
264 | .Pp | |
265 | The session terminates when the command or shell on the remote | |
266 | machine exits and all X11 and TCP/IP connections have been closed. | |
540d72c3 | 267 | The exit status of the remote program is returned as the exit status of |
3c0ef626 | 268 | .Nm ssh . |
3c0ef626 | 269 | .Ss Escape Characters |
540d72c3 | 270 | When a pseudo-terminal has been requested, |
271 | .Nm | |
272 | supports a number of functions through the use of an escape character. | |
3c0ef626 | 273 | .Pp |
274 | A single tilde character can be sent as | |
275 | .Ic ~~ | |
276 | or by following the tilde by a character other than those described below. | |
277 | The escape character must always follow a newline to be interpreted as | |
278 | special. | |
279 | The escape character can be changed in configuration files using the | |
280 | .Cm EscapeChar | |
281 | configuration directive or on the command line by the | |
282 | .Fl e | |
283 | option. | |
284 | .Pp | |
285 | The supported escapes (assuming the default | |
286 | .Ql ~ ) | |
287 | are: | |
288 | .Bl -tag -width Ds | |
289 | .It Cm ~. | |
540d72c3 | 290 | Disconnect. |
3c0ef626 | 291 | .It Cm ~^Z |
540d72c3 | 292 | Background |
293 | .Nm ssh . | |
3c0ef626 | 294 | .It Cm ~# |
540d72c3 | 295 | List forwarded connections. |
3c0ef626 | 296 | .It Cm ~& |
540d72c3 | 297 | Background |
298 | .Nm | |
299 | at logout when waiting for forwarded connection / X11 sessions to terminate. | |
3c0ef626 | 300 | .It Cm ~? |
540d72c3 | 301 | Display a list of escape characters. |
7cac2b65 | 302 | .It Cm ~B |
540d72c3 | 303 | Send a BREAK to the remote system |
304 | (only useful for SSH protocol version 2 and if the peer supports it). | |
db32a221 | 305 | .It Cm ~C |
7e82606e | 306 | Open command line. |
307 | Currently this allows the addition of port forwardings using the | |
db32a221 | 308 | .Fl L |
309 | and | |
310 | .Fl R | |
7e82606e | 311 | options (see below). |
312 | It also allows the cancellation of existing remote port-forwardings | |
313 | using | |
314 | .Fl KR Ar hostport . | |
315 | Basic help is available, using the | |
316 | .Fl h | |
317 | option. | |
3c0ef626 | 318 | .It Cm ~R |
540d72c3 | 319 | Request rekeying of the connection |
320 | (only useful for SSH protocol version 2 and if the peer supports it). | |
3c0ef626 | 321 | .El |
3c0ef626 | 322 | .Ss X11 and TCP forwarding |
3c0ef626 | 323 | If the |
324 | .Cm ForwardX11 | |
325 | variable is set to | |
326 | .Dq yes | |
540d72c3 | 327 | (or see the description of the |
3c0ef626 | 328 | .Fl X |
329 | and | |
330 | .Fl x | |
331 | options described later) | |
332 | and the user is using X11 (the | |
333 | .Ev DISPLAY | |
334 | environment variable is set), the connection to the X11 display is | |
335 | automatically forwarded to the remote side in such a way that any X11 | |
336 | programs started from the shell (or command) will go through the | |
337 | encrypted channel, and the connection to the real X server will be made | |
338 | from the local machine. | |
339 | The user should not manually set | |
340 | .Ev DISPLAY . | |
341 | Forwarding of X11 connections can be | |
342 | configured on the command line or in configuration files. | |
343 | .Pp | |
344 | The | |
345 | .Ev DISPLAY | |
346 | value set by | |
347 | .Nm | |
540d72c3 | 348 | will point to the server machine, but with a display number greater than zero. |
3c0ef626 | 349 | This is normal, and happens because |
350 | .Nm | |
351 | creates a | |
352 | .Dq proxy | |
353 | X server on the server machine for forwarding the | |
354 | connections over the encrypted channel. | |
355 | .Pp | |
356 | .Nm | |
357 | will also automatically set up Xauthority data on the server machine. | |
358 | For this purpose, it will generate a random authorization cookie, | |
359 | store it in Xauthority on the server, and verify that any forwarded | |
360 | connections carry this cookie and replace it by the real cookie when | |
361 | the connection is opened. | |
362 | The real authentication cookie is never | |
363 | sent to the server machine (and no cookies are sent in the plain). | |
364 | .Pp | |
d03f4262 | 365 | If the |
366 | .Cm ForwardAgent | |
367 | variable is set to | |
368 | .Dq yes | |
540d72c3 | 369 | (or see the description of the |
d03f4262 | 370 | .Fl A |
371 | and | |
372 | .Fl a | |
bfe49944 | 373 | options described later) and |
d03f4262 | 374 | the user is using an authentication agent, the connection to the agent |
375 | is automatically forwarded to the remote side. | |
3c0ef626 | 376 | .Pp |
377 | Forwarding of arbitrary TCP/IP connections over the secure channel can | |
378 | be specified either on the command line or in a configuration file. | |
379 | One possible application of TCP/IP forwarding is a secure connection to an | |
380 | electronic purse; another is going through firewalls. | |
3c0ef626 | 381 | .Ss Server authentication |
3c0ef626 | 382 | .Nm |
383 | automatically maintains and checks a database containing | |
384 | identifications for all hosts it has ever been used with. | |
385 | Host keys are stored in | |
386 | .Pa $HOME/.ssh/known_hosts | |
387 | in the user's home directory. | |
388 | Additionally, the file | |
db32a221 | 389 | .Pa /etc/ssh/ssh_known_hosts |
3c0ef626 | 390 | is automatically checked for known hosts. |
391 | Any new hosts are automatically added to the user's file. | |
540d72c3 | 392 | If a host's identification ever changes, |
3c0ef626 | 393 | .Nm |
394 | warns about this and disables password authentication to prevent a | |
395 | trojan horse from getting the user's password. | |
540d72c3 | 396 | Another purpose of this mechanism is to prevent man-in-the-middle attacks |
397 | which could otherwise be used to circumvent the encryption. | |
3c0ef626 | 398 | The |
399 | .Cm StrictHostKeyChecking | |
44a053a3 | 400 | option can be used to prevent logins to machines whose |
3c0ef626 | 401 | host key is not known or has changed. |
402 | .Pp | |
7e82606e | 403 | .Nm |
404 | can be configured to verify host identification using fingerprint resource | |
405 | records (SSHFP) published in DNS. | |
406 | The | |
407 | .Cm VerifyHostKeyDNS | |
408 | option can be used to control how DNS lookups are performed. | |
409 | SSHFP resource records can be generated using | |
410 | .Xr ssh-keygen 1 . | |
411 | .Pp | |
3c0ef626 | 412 | The options are as follows: |
413 | .Bl -tag -width Ds | |
540d72c3 | 414 | .It Fl 1 |
415 | Forces | |
416 | .Nm | |
417 | to try protocol version 1 only. | |
418 | .It Fl 2 | |
419 | Forces | |
420 | .Nm | |
421 | to try protocol version 2 only. | |
422 | .It Fl 4 | |
423 | Forces | |
424 | .Nm | |
425 | to use IPv4 addresses only. | |
426 | .It Fl 6 | |
427 | Forces | |
428 | .Nm | |
429 | to use IPv6 addresses only. | |
3c0ef626 | 430 | .It Fl A |
431 | Enables forwarding of the authentication agent connection. | |
432 | This can also be specified on a per-host basis in a configuration file. | |
d03f4262 | 433 | .Pp |
bfe49944 | 434 | Agent forwarding should be enabled with caution. |
435 | Users with the ability to bypass file permissions on the remote host | |
436 | (for the agent's Unix-domain socket) | |
437 | can access the local agent through the forwarded connection. | |
438 | An attacker cannot obtain key material from the agent, | |
d03f4262 | 439 | however they can perform operations on the keys that enable them to |
440 | authenticate using the identities loaded into the agent. | |
540d72c3 | 441 | .It Fl a |
442 | Disables forwarding of the authentication agent connection. | |
3c0ef626 | 443 | .It Fl b Ar bind_address |
444 | Specify the interface to transmit from on machines with multiple | |
445 | interfaces or aliased addresses. | |
540d72c3 | 446 | .It Fl C |
447 | Requests compression of all data (including stdin, stdout, stderr, and | |
448 | data for forwarded X11 and TCP/IP connections). | |
449 | The compression algorithm is the same used by | |
450 | .Xr gzip 1 , | |
451 | and the | |
452 | .Dq level | |
453 | can be controlled by the | |
454 | .Cm CompressionLevel | |
455 | option for protocol version 1. | |
456 | Compression is desirable on modem lines and other | |
457 | slow connections, but will only slow down things on fast networks. | |
458 | The default value can be set on a host-by-host basis in the | |
459 | configuration files; see the | |
460 | .Cm Compression | |
461 | option. | |
7e82606e | 462 | .It Fl c Ar cipher_spec |
463 | Selects the cipher specification for encrypting the session. | |
464 | .Pp | |
465 | Protocol version 1 allows specification of a single cipher. | |
466 | The suported values are | |
467 | .Dq 3des , | |
468 | .Dq blowfish | |
469 | and | |
470 | .Dq des . | |
3c0ef626 | 471 | .Ar 3des |
472 | (triple-des) is an encrypt-decrypt-encrypt triple with three different keys. | |
7e82606e | 473 | It is believed to be secure. |
3c0ef626 | 474 | .Ar blowfish |
540d72c3 | 475 | is a fast block cipher; it appears very secure and is much faster than |
3c0ef626 | 476 | .Ar 3des . |
477 | .Ar des | |
478 | is only supported in the | |
479 | .Nm | |
480 | client for interoperability with legacy protocol 1 implementations | |
481 | that do not support the | |
482 | .Ar 3des | |
bfe49944 | 483 | cipher. |
484 | Its use is strongly discouraged due to cryptographic weaknesses. | |
7e82606e | 485 | The default is |
486 | .Dq 3des . | |
487 | .Pp | |
488 | For protocol version 2 | |
489 | .Ar cipher_spec | |
490 | is a comma-separated list of ciphers | |
491 | listed in order of preference. | |
492 | The supported ciphers are | |
493 | .Dq 3des-cbc , | |
494 | .Dq aes128-cbc , | |
495 | .Dq aes192-cbc , | |
496 | .Dq aes256-cbc , | |
497 | .Dq aes128-ctr , | |
498 | .Dq aes192-ctr , | |
499 | .Dq aes256-ctr , | |
500 | .Dq arcfour , | |
501 | .Dq blowfish-cbc , | |
502 | and | |
503 | .Dq cast128-cbc . | |
504 | The default is | |
505 | .Bd -literal | |
506 | ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour, | |
507 | aes192-cbc,aes256-cbc'' | |
508 | .Ed | |
540d72c3 | 509 | .It Fl D Ar port |
510 | Specifies a local | |
511 | .Dq dynamic | |
512 | application-level port forwarding. | |
513 | This works by allocating a socket to listen to | |
514 | .Ar port | |
515 | on the local side, and whenever a connection is made to this port, the | |
516 | connection is forwarded over the secure channel, and the application | |
517 | protocol is then used to determine where to connect to from the | |
518 | remote machine. | |
519 | Currently the SOCKS4 and SOCKS5 protocols are supported, and | |
520 | .Nm | |
521 | will act as a SOCKS server. | |
522 | Only root can forward privileged ports. | |
523 | Dynamic port forwardings can also be specified in the configuration file. | |
524 | .It Fl e Ar ch | ^ch | none | |
3c0ef626 | 525 | Sets the escape character for sessions with a pty (default: |
526 | .Ql ~ ) . | |
527 | The escape character is only recognized at the beginning of a line. | |
528 | The escape character followed by a dot | |
529 | .Pq Ql \&. | |
540d72c3 | 530 | closes the connection; |
531 | followed by control-Z suspends the connection; | |
532 | and followed by itself sends the escape character once. | |
3c0ef626 | 533 | Setting the character to |
534 | .Dq none | |
535 | disables any escapes and makes the session fully transparent. | |
540d72c3 | 536 | .It Fl F Ar configfile |
537 | Specifies an alternative per-user configuration file. | |
538 | If a configuration file is given on the command line, | |
539 | the system-wide configuration file | |
540 | .Pq Pa /etc/ssh/ssh_config | |
541 | will be ignored. | |
542 | The default for the per-user configuration file is | |
543 | .Pa $HOME/.ssh/config . | |
3c0ef626 | 544 | .It Fl f |
545 | Requests | |
546 | .Nm | |
547 | to go to background just before command execution. | |
548 | This is useful if | |
549 | .Nm | |
550 | is going to ask for passwords or passphrases, but the user | |
551 | wants it in the background. | |
552 | This implies | |
553 | .Fl n . | |
554 | The recommended way to start X11 programs at a remote site is with | |
555 | something like | |
556 | .Ic ssh -f host xterm . | |
557 | .It Fl g | |
558 | Allows remote hosts to connect to local forwarded ports. | |
540d72c3 | 559 | .It Fl I Ar smartcard_device |
560 | Specifies which smartcard device to use. | |
561 | The argument is the device | |
562 | .Nm | |
563 | should use to communicate with a smartcard used for storing the user's | |
564 | private RSA key. | |
3c0ef626 | 565 | .It Fl i Ar identity_file |
db32a221 | 566 | Selects a file from which the identity (private key) for |
3c0ef626 | 567 | RSA or DSA authentication is read. |
db32a221 | 568 | The default is |
3c0ef626 | 569 | .Pa $HOME/.ssh/identity |
db32a221 | 570 | for protocol version 1, and |
571 | .Pa $HOME/.ssh/id_rsa | |
572 | and | |
573 | .Pa $HOME/.ssh/id_dsa | |
574 | for protocol version 2. | |
3c0ef626 | 575 | Identity files may also be specified on |
576 | a per-host basis in the configuration file. | |
577 | It is possible to have multiple | |
578 | .Fl i | |
579 | options (and multiple identities specified in | |
580 | configuration files). | |
3c0ef626 | 581 | .It Fl k |
540d72c3 | 582 | Disables forwarding (delegation) of GSSAPI credentials to the server. |
583 | .It Fl L Xo | |
584 | .Sm off | |
585 | .Ar port : host : hostport | |
586 | .Sm on | |
587 | .Xc | |
588 | Specifies that the given port on the local (client) host is to be | |
589 | forwarded to the given host and port on the remote side. | |
590 | This works by allocating a socket to listen to | |
591 | .Ar port | |
592 | on the local side, and whenever a connection is made to this port, the | |
593 | connection is forwarded over the secure channel, and a connection is | |
594 | made to | |
595 | .Ar host | |
596 | port | |
597 | .Ar hostport | |
598 | from the remote machine. | |
599 | Port forwardings can also be specified in the configuration file. | |
600 | Only root can forward privileged ports. | |
601 | IPv6 addresses can be specified with an alternative syntax: | |
602 | .Sm off | |
603 | .Xo | |
604 | .Ar port No / Ar host No / | |
605 | .Ar hostport . | |
606 | .Xc | |
607 | .Sm on | |
3c0ef626 | 608 | .It Fl l Ar login_name |
609 | Specifies the user to log in as on the remote machine. | |
610 | This also may be specified on a per-host basis in the configuration file. | |
7e82606e | 611 | .It Fl M |
612 | Places the | |
613 | .Nm | |
614 | client into | |
615 | .Dq master | |
616 | mode for connection sharing. | |
617 | Refer to the description of | |
618 | .Cm ControlMaster | |
619 | in | |
620 | .Xr ssh_config 5 | |
621 | for details. | |
3c0ef626 | 622 | .It Fl m Ar mac_spec |
623 | Additionally, for protocol version 2 a comma-separated list of MAC | |
624 | (message authentication code) algorithms can | |
625 | be specified in order of preference. | |
626 | See the | |
627 | .Cm MACs | |
628 | keyword for more information. | |
540d72c3 | 629 | .It Fl N |
630 | Do not execute a remote command. | |
631 | This is useful for just forwarding ports | |
632 | (protocol version 2 only). | |
3c0ef626 | 633 | .It Fl n |
634 | Redirects stdin from | |
635 | .Pa /dev/null | |
636 | (actually, prevents reading from stdin). | |
637 | This must be used when | |
638 | .Nm | |
639 | is run in the background. | |
640 | A common trick is to use this to run X11 programs on a remote machine. | |
641 | For example, | |
642 | .Ic ssh -n shadows.cs.hut.fi emacs & | |
643 | will start an emacs on shadows.cs.hut.fi, and the X11 | |
644 | connection will be automatically forwarded over an encrypted channel. | |
645 | The | |
646 | .Nm | |
647 | program will be put in the background. | |
648 | (This does not work if | |
649 | .Nm | |
650 | needs to ask for a password or passphrase; see also the | |
651 | .Fl f | |
652 | option.) | |
3c0ef626 | 653 | .It Fl o Ar option |
654 | Can be used to give options in the format used in the configuration file. | |
655 | This is useful for specifying options for which there is no separate | |
656 | command-line flag. | |
540d72c3 | 657 | For full details of the options listed below, and their possible values, see |
658 | .Xr ssh_config 5 . | |
659 | .Pp | |
660 | .Bl -tag -width Ds -offset indent -compact | |
661 | .It AddressFamily | |
662 | .It BatchMode | |
663 | .It BindAddress | |
664 | .It ChallengeResponseAuthentication | |
665 | .It CheckHostIP | |
666 | .It Cipher | |
667 | .It Ciphers | |
668 | .It ClearAllForwardings | |
669 | .It Compression | |
670 | .It CompressionLevel | |
671 | .It ConnectionAttempts | |
7e82606e | 672 | .It ConnectTimeout |
673 | .It ControlMaster | |
674 | .It ControlPath | |
540d72c3 | 675 | .It DynamicForward |
676 | .It EscapeChar | |
677 | .It ForwardAgent | |
678 | .It ForwardX11 | |
679 | .It ForwardX11Trusted | |
680 | .It GatewayPorts | |
681 | .It GlobalKnownHostsFile | |
682 | .It GSSAPIAuthentication | |
683 | .It GSSAPIDelegateCredentials | |
684 | .It Host | |
685 | .It HostbasedAuthentication | |
686 | .It HostKeyAlgorithms | |
687 | .It HostKeyAlias | |
688 | .It HostName | |
689 | .It IdentityFile | |
12a403af | 690 | .It IdentitiesOnly |
540d72c3 | 691 | .It LocalForward |
692 | .It LogLevel | |
693 | .It MACs | |
694 | .It NoHostAuthenticationForLocalhost | |
695 | .It NumberOfPasswordPrompts | |
696 | .It PasswordAuthentication | |
697 | .It Port | |
698 | .It PreferredAuthentications | |
699 | .It Protocol | |
700 | .It ProxyCommand | |
701 | .It PubkeyAuthentication | |
702 | .It RemoteForward | |
703 | .It RhostsRSAAuthentication | |
704 | .It RSAAuthentication | |
7e82606e | 705 | .It SendEnv |
540d72c3 | 706 | .It ServerAliveInterval |
707 | .It ServerAliveCountMax | |
708 | .It SmartcardDevice | |
709 | .It StrictHostKeyChecking | |
710 | .It TCPKeepAlive | |
711 | .It UsePrivilegedPort | |
712 | .It User | |
713 | .It UserKnownHostsFile | |
714 | .It VerifyHostKeyDNS | |
715 | .It XAuthLocation | |
716 | .El | |
3c0ef626 | 717 | .It Fl p Ar port |
718 | Port to connect to on the remote host. | |
719 | This can be specified on a | |
720 | per-host basis in the configuration file. | |
3c0ef626 | 721 | .It Fl q |
722 | Quiet mode. | |
723 | Causes all warning and diagnostic messages to be suppressed. | |
540d72c3 | 724 | .It Fl R Xo |
725 | .Sm off | |
726 | .Ar port : host : hostport | |
727 | .Sm on | |
728 | .Xc | |
729 | Specifies that the given port on the remote (server) host is to be | |
730 | forwarded to the given host and port on the local side. | |
731 | This works by allocating a socket to listen to | |
732 | .Ar port | |
733 | on the remote side, and whenever a connection is made to this port, the | |
734 | connection is forwarded over the secure channel, and a connection is | |
735 | made to | |
736 | .Ar host | |
737 | port | |
738 | .Ar hostport | |
739 | from the local machine. | |
740 | Port forwardings can also be specified in the configuration file. | |
741 | Privileged ports can be forwarded only when | |
742 | logging in as root on the remote machine. | |
743 | IPv6 addresses can be specified with an alternative syntax: | |
744 | .Sm off | |
745 | .Xo | |
746 | .Ar port No / Ar host No / | |
747 | .Ar hostport . | |
748 | .Xc | |
749 | .Sm on | |
7e82606e | 750 | .It Fl S Ar ctl |
751 | Specifies the location of a control socket for connection sharing. | |
752 | Refer to the description of | |
753 | .Cm ControlPath | |
754 | and | |
755 | .Cm ControlMaster | |
756 | in | |
757 | .Xr ssh_config 5 | |
758 | for details. | |
3c0ef626 | 759 | .It Fl s |
7cac2b65 | 760 | May be used to request invocation of a subsystem on the remote system. |
761 | Subsystems are a feature of the SSH2 protocol which facilitate the use | |
540d72c3 | 762 | of SSH as a secure transport for other applications (eg.\& |
763 | .Xr sftp 1 ) . | |
7cac2b65 | 764 | The subsystem is specified as the remote command. |
540d72c3 | 765 | .It Fl T |
766 | Disable pseudo-tty allocation. | |
3c0ef626 | 767 | .It Fl t |
768 | Force pseudo-tty allocation. | |
769 | This can be used to execute arbitrary | |
770 | screen-based programs on a remote machine, which can be very useful, | |
771 | e.g., when implementing menu services. | |
772 | Multiple | |
773 | .Fl t | |
774 | options force tty allocation, even if | |
775 | .Nm | |
776 | has no local tty. | |
540d72c3 | 777 | .It Fl V |
778 | Display the version number and exit. | |
3c0ef626 | 779 | .It Fl v |
780 | Verbose mode. | |
781 | Causes | |
782 | .Nm | |
783 | to print debugging messages about its progress. | |
784 | This is helpful in | |
785 | debugging connection, authentication, and configuration problems. | |
786 | Multiple | |
787 | .Fl v | |
7cac2b65 | 788 | options increase the verbosity. |
789 | The maximum is 3. | |
3c0ef626 | 790 | .It Fl X |
791 | Enables X11 forwarding. | |
792 | This can also be specified on a per-host basis in a configuration file. | |
d03f4262 | 793 | .Pp |
bfe49944 | 794 | X11 forwarding should be enabled with caution. |
795 | Users with the ability to bypass file permissions on the remote host | |
796 | (for the user's X authorization database) | |
797 | can access the local X11 display through the forwarded connection. | |
798 | An attacker may then be able to perform activities such as keystroke monitoring. | |
540d72c3 | 799 | .It Fl x |
800 | Disables X11 forwarding. | |
801 | .It Fl Y | |
802 | Enables trusted X11 forwarding. | |
3c0ef626 | 803 | .El |
804 | .Sh CONFIGURATION FILES | |
805 | .Nm | |
44a053a3 | 806 | may additionally obtain configuration data from |
807 | a per-user configuration file and a system-wide configuration file. | |
808 | The file format and configuration options are described in | |
809 | .Xr ssh_config 5 . | |
3c0ef626 | 810 | .Sh ENVIRONMENT |
811 | .Nm | |
812 | will normally set the following environment variables: | |
540d72c3 | 813 | .Bl -tag -width LOGNAME |
3c0ef626 | 814 | .It Ev DISPLAY |
815 | The | |
816 | .Ev DISPLAY | |
817 | variable indicates the location of the X11 server. | |
818 | It is automatically set by | |
819 | .Nm | |
820 | to point to a value of the form | |
821 | .Dq hostname:n | |
822 | where hostname indicates | |
540d72c3 | 823 | the host where the shell runs, and n is an integer \*(Ge 1. |
3c0ef626 | 824 | .Nm |
825 | uses this special value to forward X11 connections over the secure | |
826 | channel. | |
827 | The user should normally not set | |
828 | .Ev DISPLAY | |
829 | explicitly, as that | |
830 | will render the X11 connection insecure (and will require the user to | |
831 | manually copy any required authorization cookies). | |
832 | .It Ev HOME | |
833 | Set to the path of the user's home directory. | |
834 | .It Ev LOGNAME | |
835 | Synonym for | |
836 | .Ev USER ; | |
837 | set for compatibility with systems that use this variable. | |
838 | .It Ev MAIL | |
839 | Set to the path of the user's mailbox. | |
840 | .It Ev PATH | |
841 | Set to the default | |
842 | .Ev PATH , | |
843 | as specified when compiling | |
844 | .Nm ssh . | |
845 | .It Ev SSH_ASKPASS | |
846 | If | |
847 | .Nm | |
848 | needs a passphrase, it will read the passphrase from the current | |
849 | terminal if it was run from a terminal. | |
850 | If | |
851 | .Nm | |
852 | does not have a terminal associated with it but | |
853 | .Ev DISPLAY | |
854 | and | |
855 | .Ev SSH_ASKPASS | |
856 | are set, it will execute the program specified by | |
857 | .Ev SSH_ASKPASS | |
858 | and open an X11 window to read the passphrase. | |
859 | This is particularly useful when calling | |
860 | .Nm | |
861 | from a | |
862 | .Pa .Xsession | |
863 | or related script. | |
864 | (Note that on some machines it | |
865 | may be necessary to redirect the input from | |
866 | .Pa /dev/null | |
867 | to make this work.) | |
868 | .It Ev SSH_AUTH_SOCK | |
869 | Identifies the path of a unix-domain socket used to communicate with the | |
870 | agent. | |
d03f4262 | 871 | .It Ev SSH_CONNECTION |
872 | Identifies the client and server ends of the connection. | |
3c0ef626 | 873 | The variable contains |
d03f4262 | 874 | four space-separated values: client ip-address, client port number, |
875 | server ip-address and server port number. | |
3c0ef626 | 876 | .It Ev SSH_ORIGINAL_COMMAND |
877 | The variable contains the original command line if a forced command | |
878 | is executed. | |
879 | It can be used to extract the original arguments. | |
880 | .It Ev SSH_TTY | |
881 | This is set to the name of the tty (path to the device) associated | |
882 | with the current shell or command. | |
883 | If the current session has no tty, | |
884 | this variable is not set. | |
885 | .It Ev TZ | |
886 | The timezone variable is set to indicate the present timezone if it | |
887 | was set when the daemon was started (i.e., the daemon passes the value | |
888 | on to new connections). | |
889 | .It Ev USER | |
890 | Set to the name of the user logging in. | |
891 | .El | |
892 | .Pp | |
893 | Additionally, | |
894 | .Nm | |
895 | reads | |
896 | .Pa $HOME/.ssh/environment , | |
897 | and adds lines of the format | |
898 | .Dq VARNAME=value | |
d03f4262 | 899 | to the environment if the file exists and if users are allowed to |
900 | change their environment. | |
540d72c3 | 901 | For more information, see the |
d03f4262 | 902 | .Cm PermitUserEnvironment |
903 | option in | |
904 | .Xr sshd_config 5 . | |
3c0ef626 | 905 | .Sh FILES |
906 | .Bl -tag -width Ds | |
907 | .It Pa $HOME/.ssh/known_hosts | |
908 | Records host keys for all hosts the user has logged into that are not | |
909 | in | |
db32a221 | 910 | .Pa /etc/ssh/ssh_known_hosts . |
3c0ef626 | 911 | See |
912 | .Xr sshd 8 . | |
913 | .It Pa $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa | |
914 | Contains the authentication identity of the user. | |
915 | They are for protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively. | |
916 | These files | |
917 | contain sensitive data and should be readable by the user but not | |
918 | accessible by others (read/write/execute). | |
919 | Note that | |
920 | .Nm | |
921 | ignores a private key file if it is accessible by others. | |
922 | It is possible to specify a passphrase when | |
923 | generating the key; the passphrase will be used to encrypt the | |
924 | sensitive part of this file using 3DES. | |
925 | .It Pa $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub | |
926 | Contains the public key for authentication (public part of the | |
927 | identity file in human-readable form). | |
928 | The contents of the | |
929 | .Pa $HOME/.ssh/identity.pub | |
540d72c3 | 930 | file should be added to the file |
3c0ef626 | 931 | .Pa $HOME/.ssh/authorized_keys |
932 | on all machines | |
933 | where the user wishes to log in using protocol version 1 RSA authentication. | |
934 | The contents of the | |
935 | .Pa $HOME/.ssh/id_dsa.pub | |
936 | and | |
937 | .Pa $HOME/.ssh/id_rsa.pub | |
938 | file should be added to | |
939 | .Pa $HOME/.ssh/authorized_keys | |
940 | on all machines | |
941 | where the user wishes to log in using protocol version 2 DSA/RSA authentication. | |
942 | These files are not | |
943 | sensitive and can (but need not) be readable by anyone. | |
944 | These files are | |
945 | never used automatically and are not necessary; they are only provided for | |
946 | the convenience of the user. | |
947 | .It Pa $HOME/.ssh/config | |
948 | This is the per-user configuration file. | |
44a053a3 | 949 | The file format and configuration options are described in |
950 | .Xr ssh_config 5 . | |
7e82606e | 951 | Because of the potential for abuse, this file must have strict permissions: |
952 | read/write for the user, and not accessible by others. | |
3c0ef626 | 953 | .It Pa $HOME/.ssh/authorized_keys |
954 | Lists the public keys (RSA/DSA) that can be used for logging in as this user. | |
955 | The format of this file is described in the | |
956 | .Xr sshd 8 | |
957 | manual page. | |
540d72c3 | 958 | In the simplest form the format is the same as the |
959 | .Pa .pub | |
3c0ef626 | 960 | identity files. |
961 | This file is not highly sensitive, but the recommended | |
962 | permissions are read/write for the user, and not accessible by others. | |
db32a221 | 963 | .It Pa /etc/ssh/ssh_known_hosts |
3c0ef626 | 964 | Systemwide list of known host keys. |
965 | This file should be prepared by the | |
966 | system administrator to contain the public host keys of all machines in the | |
967 | organization. | |
968 | This file should be world-readable. | |
969 | This file contains | |
970 | public keys, one per line, in the following format (fields separated | |
971 | by spaces): system name, public key and optional comment field. | |
972 | When different names are used | |
973 | for the same machine, all such names should be listed, separated by | |
974 | commas. | |
540d72c3 | 975 | The format is described in the |
3c0ef626 | 976 | .Xr sshd 8 |
977 | manual page. | |
978 | .Pp | |
979 | The canonical system name (as returned by name servers) is used by | |
980 | .Xr sshd 8 | |
981 | to verify the client host when logging in; other names are needed because | |
982 | .Nm | |
983 | does not convert the user-supplied name to a canonical name before | |
984 | checking the key, because someone with access to the name servers | |
985 | would then be able to fool host authentication. | |
db32a221 | 986 | .It Pa /etc/ssh/ssh_config |
3c0ef626 | 987 | Systemwide configuration file. |
44a053a3 | 988 | The file format and configuration options are described in |
989 | .Xr ssh_config 5 . | |
db32a221 | 990 | .It Pa /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key |
3c0ef626 | 991 | These three files contain the private parts of the host keys |
992 | and are used for | |
993 | .Cm RhostsRSAAuthentication | |
994 | and | |
995 | .Cm HostbasedAuthentication . | |
44a053a3 | 996 | If the protocol version 1 |
997 | .Cm RhostsRSAAuthentication | |
998 | method is used, | |
999 | .Nm | |
1000 | must be setuid root, since the host key is readable only by root. | |
1001 | For protocol version 2, | |
1002 | .Nm | |
1003 | uses | |
1004 | .Xr ssh-keysign 8 | |
1005 | to access the host keys for | |
1006 | .Cm HostbasedAuthentication . | |
1007 | This eliminates the requirement that | |
1008 | .Nm | |
1009 | be setuid root when that authentication method is used. | |
1010 | By default | |
3c0ef626 | 1011 | .Nm |
44a053a3 | 1012 | is not setuid root. |
3c0ef626 | 1013 | .It Pa $HOME/.rhosts |
1014 | This file is used in | |
540d72c3 | 1015 | .Em rhosts |
3c0ef626 | 1016 | authentication to list the |
1017 | host/user pairs that are permitted to log in. | |
1018 | (Note that this file is | |
1019 | also used by rlogin and rsh, which makes using this file insecure.) | |
1020 | Each line of the file contains a host name (in the canonical form | |
1021 | returned by name servers), and then a user name on that host, | |
1022 | separated by a space. | |
1023 | On some machines this file may need to be | |
1024 | world-readable if the user's home directory is on a NFS partition, | |
1025 | because | |
1026 | .Xr sshd 8 | |
1027 | reads it as root. | |
1028 | Additionally, this file must be owned by the user, | |
1029 | and must not have write permissions for anyone else. | |
1030 | The recommended | |
1031 | permission for most machines is read/write for the user, and not | |
1032 | accessible by others. | |
1033 | .Pp | |
1034 | Note that by default | |
1035 | .Xr sshd 8 | |
1036 | will be installed so that it requires successful RSA host | |
540d72c3 | 1037 | authentication before permitting |
1038 | .Em rhosts | |
1039 | authentication. | |
3c0ef626 | 1040 | If the server machine does not have the client's host key in |
db32a221 | 1041 | .Pa /etc/ssh/ssh_known_hosts , |
3c0ef626 | 1042 | it can be stored in |
1043 | .Pa $HOME/.ssh/known_hosts . | |
1044 | The easiest way to do this is to | |
1045 | connect back to the client from the server machine using ssh; this | |
1046 | will automatically add the host key to | |
1047 | .Pa $HOME/.ssh/known_hosts . | |
1048 | .It Pa $HOME/.shosts | |
1049 | This file is used exactly the same way as | |
540d72c3 | 1050 | .Pa .rhosts . |
3c0ef626 | 1051 | The purpose for |
1052 | having this file is to be able to use rhosts authentication with | |
1053 | .Nm | |
1054 | without permitting login with | |
540d72c3 | 1055 | .Xr rlogin |
3c0ef626 | 1056 | or |
1057 | .Xr rsh 1 . | |
1058 | .It Pa /etc/hosts.equiv | |
1059 | This file is used during | |
540d72c3 | 1060 | .Em rhosts |
7cac2b65 | 1061 | authentication. |
3c0ef626 | 1062 | It contains |
540d72c3 | 1063 | canonical hosts names, one per line (the full format is described in the |
3c0ef626 | 1064 | .Xr sshd 8 |
1065 | manual page). | |
1066 | If the client host is found in this file, login is | |
1067 | automatically permitted provided client and server user names are the | |
1068 | same. | |
1069 | Additionally, successful RSA host authentication is normally | |
1070 | required. | |
1071 | This file should only be writable by root. | |
1072 | .It Pa /etc/shosts.equiv | |
1073 | This file is processed exactly as | |
1074 | .Pa /etc/hosts.equiv . | |
1075 | This file may be useful to permit logins using | |
1076 | .Nm | |
1077 | but not using rsh/rlogin. | |
db32a221 | 1078 | .It Pa /etc/ssh/sshrc |
3c0ef626 | 1079 | Commands in this file are executed by |
1080 | .Nm | |
1081 | when the user logs in just before the user's shell (or command) is started. | |
1082 | See the | |
1083 | .Xr sshd 8 | |
1084 | manual page for more information. | |
1085 | .It Pa $HOME/.ssh/rc | |
1086 | Commands in this file are executed by | |
1087 | .Nm | |
1088 | when the user logs in just before the user's shell (or command) is | |
1089 | started. | |
1090 | See the | |
1091 | .Xr sshd 8 | |
1092 | manual page for more information. | |
1093 | .It Pa $HOME/.ssh/environment | |
1094 | Contains additional definitions for environment variables, see section | |
1095 | .Sx ENVIRONMENT | |
1096 | above. | |
1097 | .El | |
db32a221 | 1098 | .Sh DIAGNOSTICS |
1099 | .Nm | |
1100 | exits with the exit status of the remote command or with 255 | |
1101 | if an error occurred. | |
3c0ef626 | 1102 | .Sh SEE ALSO |
540d72c3 | 1103 | .Xr gzip 1 , |
3c0ef626 | 1104 | .Xr rsh 1 , |
1105 | .Xr scp 1 , | |
1106 | .Xr sftp 1 , | |
1107 | .Xr ssh-add 1 , | |
1108 | .Xr ssh-agent 1 , | |
1109 | .Xr ssh-keygen 1 , | |
1110 | .Xr telnet 1 , | |
540d72c3 | 1111 | .Xr hosts.equiv 5 , |
276b07a3 | 1112 | .Xr ssh_config 5 , |
1113 | .Xr ssh-keysign 8 , | |
3c0ef626 | 1114 | .Xr sshd 8 |
1115 | .Rs | |
1116 | .%A T. Ylonen | |
1117 | .%A T. Kivinen | |
1118 | .%A M. Saarinen | |
1119 | .%A T. Rinne | |
1120 | .%A S. Lehtinen | |
1121 | .%T "SSH Protocol Architecture" | |
db32a221 | 1122 | .%N draft-ietf-secsh-architecture-12.txt |
1123 | .%D January 2002 | |
3c0ef626 | 1124 | .%O work in progress material |
1125 | .Re | |
7cac2b65 | 1126 | .Sh AUTHORS |
1127 | OpenSSH is a derivative of the original and free | |
1128 | ssh 1.2.12 release by Tatu Ylonen. | |
1129 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
1130 | Theo de Raadt and Dug Song | |
1131 | removed many bugs, re-added newer features and | |
1132 | created OpenSSH. | |
1133 | Markus Friedl contributed the support for SSH | |
1134 | protocol versions 1.5 and 2.0. |