diff options
author | Colin Watson <cjwatson@debian.org> | 2007-06-12 11:03:36 +0000 |
---|---|---|
committer | Colin Watson <cjwatson@debian.org> | 2007-06-12 11:03:36 +0000 |
commit | 086ea76990b1e6287c24b6db74adffd4605eb3b0 (patch) | |
tree | 4650093038f9f66b02823fb07f49d6a4becd1667 /ssh_config.0 | |
parent | 4ee72c71e31226c81743439fe1ed2b521b5ddb7e (diff) | |
parent | 3e2e0ac10674d77618c4c7339e18b83ced247492 (diff) |
Import OpenSSH 4.6p1.
Diffstat (limited to 'ssh_config.0')
-rw-r--r-- | ssh_config.0 | 645 |
1 files changed, 645 insertions, 0 deletions
diff --git a/ssh_config.0 b/ssh_config.0 new file mode 100644 index 000000000..2ca4ee31b --- /dev/null +++ b/ssh_config.0 | |||
@@ -0,0 +1,645 @@ | |||
1 | SSH_CONFIG(5) OpenBSD Programmer's Manual SSH_CONFIG(5) | ||
2 | |||
3 | NAME | ||
4 | ssh_config - OpenSSH SSH client configuration files | ||
5 | |||
6 | SYNOPSIS | ||
7 | ~/.ssh/config | ||
8 | /etc/ssh/ssh_config | ||
9 | |||
10 | DESCRIPTION | ||
11 | ssh(1) obtains configuration data from the following sources in the fol- | ||
12 | lowing order: | ||
13 | |||
14 | 1. command-line options | ||
15 | 2. user's configuration file (~/.ssh/config) | ||
16 | 3. system-wide configuration file (/etc/ssh/ssh_config) | ||
17 | |||
18 | For each parameter, the first obtained value will be used. The configu- | ||
19 | ration files contain sections separated by ``Host'' specifications, and | ||
20 | that section is only applied for hosts that match one of the patterns | ||
21 | given in the specification. The matched host name is the one given on | ||
22 | the command line. | ||
23 | |||
24 | Since the first obtained value for each parameter is used, more host-spe- | ||
25 | cific declarations should be given near the beginning of the file, and | ||
26 | general defaults at the end. | ||
27 | |||
28 | The configuration file has the following format: | ||
29 | |||
30 | Empty lines and lines starting with `#' are comments. Otherwise a line | ||
31 | is of the format ``keyword arguments''. Configuration options may be | ||
32 | separated by whitespace or optional whitespace and exactly one `='; the | ||
33 | latter format is useful to avoid the need to quote whitespace when speci- | ||
34 | fying configuration options using the ssh, scp, and sftp -o option. Ar- | ||
35 | guments may optionally be enclosed in double quotes (") in order to rep- | ||
36 | resent arguments containing spaces. | ||
37 | |||
38 | The possible keywords and their meanings are as follows (note that key- | ||
39 | words are case-insensitive and arguments are case-sensitive): | ||
40 | |||
41 | Host Restricts the following declarations (up to the next Host key- | ||
42 | word) to be only for those hosts that match one of the patterns | ||
43 | given after the keyword. A single `*' as a pattern can be used | ||
44 | to provide global defaults for all hosts. The host is the | ||
45 | hostname argument given on the command line (i.e. the name is not | ||
46 | converted to a canonicalized host name before matching). | ||
47 | |||
48 | See PATTERNS for more information on patterns. | ||
49 | |||
50 | AddressFamily | ||
51 | Specifies which address family to use when connecting. Valid ar- | ||
52 | guments are ``any'', ``inet'' (use IPv4 only), or ``inet6'' (use | ||
53 | IPv6 only). | ||
54 | |||
55 | BatchMode | ||
56 | If set to ``yes'', passphrase/password querying will be disabled. | ||
57 | This option is useful in scripts and other batch jobs where no | ||
58 | user is present to supply the password. The argument must be | ||
59 | ``yes'' or ``no''. The default is ``no''. | ||
60 | |||
61 | BindAddress | ||
62 | Use the specified address on the local machine as the source ad- | ||
63 | dress of the connection. Only useful on systems with more than | ||
64 | one address. Note that this option does not work if | ||
65 | UsePrivilegedPort is set to ``yes''. | ||
66 | |||
67 | ChallengeResponseAuthentication | ||
68 | Specifies whether to use challenge-response authentication. The | ||
69 | argument to this keyword must be ``yes'' or ``no''. The default | ||
70 | is ``yes''. | ||
71 | |||
72 | CheckHostIP | ||
73 | If this flag is set to ``yes'', ssh(1) will additionally check | ||
74 | the host IP address in the known_hosts file. This allows ssh to | ||
75 | detect if a host key changed due to DNS spoofing. If the option | ||
76 | is set to ``no'', the check will not be executed. The default is | ||
77 | ``yes''. | ||
78 | |||
79 | Cipher Specifies the cipher to use for encrypting the session in proto- | ||
80 | col version 1. Currently, ``blowfish'', ``3des'', and ``des'' | ||
81 | are supported. des is only supported in the ssh(1) client for | ||
82 | interoperability with legacy protocol 1 implementations that do | ||
83 | not support the 3des cipher. Its use is strongly discouraged due | ||
84 | to cryptographic weaknesses. The default is ``3des''. | ||
85 | |||
86 | Ciphers | ||
87 | Specifies the ciphers allowed for protocol version 2 in order of | ||
88 | preference. Multiple ciphers must be comma-separated. The sup- | ||
89 | ported ciphers are ``3des-cbc'', ``aes128-cbc'', ``aes192-cbc'', | ||
90 | ``aes256-cbc'', ``aes128-ctr'', ``aes192-ctr'', ``aes256-ctr'', | ||
91 | ``arcfour128'', ``arcfour256'', ``arcfour'', ``blowfish-cbc'', | ||
92 | and ``cast128-cbc''. The default is: | ||
93 | |||
94 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128, | ||
95 | arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr, | ||
96 | aes192-ctr,aes256-ctr | ||
97 | |||
98 | ClearAllForwardings | ||
99 | Specifies that all local, remote, and dynamic port forwardings | ||
100 | specified in the configuration files or on the command line be | ||
101 | cleared. This option is primarily useful when used from the | ||
102 | ssh(1) command line to clear port forwardings set in configura- | ||
103 | tion files, and is automatically set by scp(1) and sftp(1). The | ||
104 | argument must be ``yes'' or ``no''. The default is ``no''. | ||
105 | |||
106 | Compression | ||
107 | Specifies whether to use compression. The argument must be | ||
108 | ``yes'' or ``no''. The default is ``no''. | ||
109 | |||
110 | CompressionLevel | ||
111 | Specifies the compression level to use if compression is enabled. | ||
112 | The argument must be an integer from 1 (fast) to 9 (slow, best). | ||
113 | The default level is 6, which is good for most applications. The | ||
114 | meaning of the values is the same as in gzip(1). Note that this | ||
115 | option applies to protocol version 1 only. | ||
116 | |||
117 | ConnectionAttempts | ||
118 | Specifies the number of tries (one per second) to make before ex- | ||
119 | iting. The argument must be an integer. This may be useful in | ||
120 | scripts if the connection sometimes fails. The default is 1. | ||
121 | |||
122 | ConnectTimeout | ||
123 | Specifies the timeout (in seconds) used when connecting to the | ||
124 | SSH server, instead of using the default system TCP timeout. | ||
125 | This value is used only when the target is down or really un- | ||
126 | reachable, not when it refuses the connection. | ||
127 | |||
128 | ControlMaster | ||
129 | Enables the sharing of multiple sessions over a single network | ||
130 | connection. When set to ``yes'', ssh(1) will listen for connec- | ||
131 | tions on a control socket specified using the ControlPath argu- | ||
132 | ment. Additional sessions can connect to this socket using the | ||
133 | same ControlPath with ControlMaster set to ``no'' (the default). | ||
134 | These sessions will try to reuse the master instance's network | ||
135 | connection rather than initiating new ones, but will fall back to | ||
136 | connecting normally if the control socket does not exist, or is | ||
137 | not listening. | ||
138 | |||
139 | Setting this to ``ask'' will cause ssh to listen for control con- | ||
140 | nections, but require confirmation using the SSH_ASKPASS program | ||
141 | before they are accepted (see ssh-add(1) for details). If the | ||
142 | ControlPath cannot be opened, ssh will continue without connect- | ||
143 | ing to a master instance. | ||
144 | |||
145 | X11 and ssh-agent(1) forwarding is supported over these multi- | ||
146 | plexed connections, however the display and agent forwarded will | ||
147 | be the one belonging to the master connection i.e. it is not pos- | ||
148 | sible to forward multiple displays or agents. | ||
149 | |||
150 | Two additional options allow for opportunistic multiplexing: try | ||
151 | to use a master connection but fall back to creating a new one if | ||
152 | one does not already exist. These options are: ``auto'' and | ||
153 | ``autoask''. The latter requires confirmation like the ``ask'' | ||
154 | option. | ||
155 | |||
156 | ControlPath | ||
157 | Specify the path to the control socket used for connection shar- | ||
158 | ing as described in the ControlMaster section above or the string | ||
159 | ``none'' to disable connection sharing. In the path, `%l' will | ||
160 | be substituted by the local host name, `%h' will be substituted | ||
161 | by the target host name, `%p' the port, and `%r' by the remote | ||
162 | login username. It is recommended that any ControlPath used for | ||
163 | opportunistic connection sharing include at least %h, %p, and %r. | ||
164 | This ensures that shared connections are uniquely identified. | ||
165 | |||
166 | DynamicForward | ||
167 | Specifies that a TCP port on the local machine be forwarded over | ||
168 | the secure channel, and the application protocol is then used to | ||
169 | determine where to connect to from the remote machine. | ||
170 | |||
171 | The argument must be [bind_address:]port. IPv6 addresses can be | ||
172 | specified by enclosing addresses in square brackets or by using | ||
173 | an alternative syntax: [bind_address/]port. By default, the lo- | ||
174 | cal port is bound in accordance with the GatewayPorts setting. | ||
175 | However, an explicit bind_address may be used to bind the connec- | ||
176 | tion to a specific address. The bind_address of ``localhost'' | ||
177 | indicates that the listening port be bound for local use only, | ||
178 | while an empty address or `*' indicates that the port should be | ||
179 | available from all interfaces. | ||
180 | |||
181 | Currently the SOCKS4 and SOCKS5 protocols are supported, and | ||
182 | ssh(1) will act as a SOCKS server. Multiple forwardings may be | ||
183 | specified, and additional forwardings can be given on the command | ||
184 | line. Only the superuser can forward privileged ports. | ||
185 | |||
186 | EnableSSHKeysign | ||
187 | Setting this option to ``yes'' in the global client configuration | ||
188 | file /etc/ssh/ssh_config enables the use of the helper program | ||
189 | ssh-keysign(8) during HostbasedAuthentication. The argument must | ||
190 | be ``yes'' or ``no''. The default is ``no''. This option should | ||
191 | be placed in the non-hostspecific section. See ssh-keysign(8) | ||
192 | for more information. | ||
193 | |||
194 | EscapeChar | ||
195 | Sets the escape character (default: `~'). The escape character | ||
196 | can also be set on the command line. The argument should be a | ||
197 | single character, `^' followed by a letter, or ``none'' to dis- | ||
198 | able the escape character entirely (making the connection trans- | ||
199 | parent for binary data). | ||
200 | |||
201 | ExitOnForwardFailure | ||
202 | Specifies whether ssh(1) should terminate the connection if it | ||
203 | cannot set up all requested dynamic, local, and remote port for- | ||
204 | wardings. The argument must be ``yes'' or ``no''. The default | ||
205 | is ``no''. | ||
206 | |||
207 | ForwardAgent | ||
208 | Specifies whether the connection to the authentication agent (if | ||
209 | any) will be forwarded to the remote machine. The argument must | ||
210 | be ``yes'' or ``no''. The default is ``no''. | ||
211 | |||
212 | Agent forwarding should be enabled with caution. Users with the | ||
213 | ability to bypass file permissions on the remote host (for the | ||
214 | agent's Unix-domain socket) can access the local agent through | ||
215 | the forwarded connection. An attacker cannot obtain key material | ||
216 | from the agent, however they can perform operations on the keys | ||
217 | that enable them to authenticate using the identities loaded into | ||
218 | the agent. | ||
219 | |||
220 | ForwardX11 | ||
221 | Specifies whether X11 connections will be automatically redirect- | ||
222 | ed over the secure channel and DISPLAY set. The argument must be | ||
223 | ``yes'' or ``no''. The default is ``no''. | ||
224 | |||
225 | X11 forwarding should be enabled with caution. Users with the | ||
226 | ability to bypass file permissions on the remote host (for the | ||
227 | user's X11 authorization database) can access the local X11 dis- | ||
228 | play through the forwarded connection. An attacker may then be | ||
229 | able to perform activities such as keystroke monitoring if the | ||
230 | ForwardX11Trusted option is also enabled. | ||
231 | |||
232 | ForwardX11Trusted | ||
233 | If this option is set to ``yes'', remote X11 clients will have | ||
234 | full access to the original X11 display. | ||
235 | |||
236 | If this option is set to ``no'', remote X11 clients will be con- | ||
237 | sidered untrusted and prevented from stealing or tampering with | ||
238 | data belonging to trusted X11 clients. Furthermore, the xauth(1) | ||
239 | token used for the session will be set to expire after 20 min- | ||
240 | utes. Remote clients will be refused access after this time. | ||
241 | |||
242 | The default is ``no''. | ||
243 | |||
244 | See the X11 SECURITY extension specification for full details on | ||
245 | the restrictions imposed on untrusted clients. | ||
246 | |||
247 | GatewayPorts | ||
248 | Specifies whether remote hosts are allowed to connect to local | ||
249 | forwarded ports. By default, ssh(1) binds local port forwardings | ||
250 | to the loopback address. This prevents other remote hosts from | ||
251 | connecting to forwarded ports. GatewayPorts can be used to spec- | ||
252 | ify that ssh should bind local port forwardings to the wildcard | ||
253 | address, thus allowing remote hosts to connect to forwarded | ||
254 | ports. The argument must be ``yes'' or ``no''. The default is | ||
255 | ``no''. | ||
256 | |||
257 | GlobalKnownHostsFile | ||
258 | Specifies a file to use for the global host key database instead | ||
259 | of /etc/ssh/ssh_known_hosts. | ||
260 | |||
261 | GSSAPIAuthentication | ||
262 | Specifies whether user authentication based on GSSAPI is allowed. | ||
263 | The default is ``no''. Note that this option applies to protocol | ||
264 | version 2 only. | ||
265 | |||
266 | GSSAPIDelegateCredentials | ||
267 | Forward (delegate) credentials to the server. The default is | ||
268 | ``no''. Note that this option applies to protocol version 2 on- | ||
269 | ly. | ||
270 | |||
271 | HashKnownHosts | ||
272 | Indicates that ssh(1) should hash host names and addresses when | ||
273 | they are added to ~/.ssh/known_hosts. These hashed names may be | ||
274 | used normally by ssh(1) and sshd(8), but they do not reveal iden- | ||
275 | tifying information should the file's contents be disclosed. The | ||
276 | default is ``no''. Note that existing names and addresses in | ||
277 | known hosts files will not be converted automatically, but may be | ||
278 | manually hashed using ssh-keygen(1). | ||
279 | |||
280 | HostbasedAuthentication | ||
281 | Specifies whether to try rhosts based authentication with public | ||
282 | key authentication. The argument must be ``yes'' or ``no''. The | ||
283 | default is ``no''. This option applies to protocol version 2 on- | ||
284 | ly and is similar to RhostsRSAAuthentication. | ||
285 | |||
286 | HostKeyAlgorithms | ||
287 | Specifies the protocol version 2 host key algorithms that the | ||
288 | client wants to use in order of preference. The default for this | ||
289 | option is: ``ssh-rsa,ssh-dss''. | ||
290 | |||
291 | HostKeyAlias | ||
292 | Specifies an alias that should be used instead of the real host | ||
293 | name when looking up or saving the host key in the host key | ||
294 | database files. This option is useful for tunneling SSH connec- | ||
295 | tions or for multiple servers running on a single host. | ||
296 | |||
297 | HostName | ||
298 | Specifies the real host name to log into. This can be used to | ||
299 | specify nicknames or abbreviations for hosts. The default is the | ||
300 | name given on the command line. Numeric IP addresses are also | ||
301 | permitted (both on the command line and in HostName specifica- | ||
302 | tions). | ||
303 | |||
304 | IdentitiesOnly | ||
305 | Specifies that ssh(1) should only use the authentication identity | ||
306 | files configured in the ssh_config files, even if ssh-agent(1) | ||
307 | offers more identities. The argument to this keyword must be | ||
308 | ``yes'' or ``no''. This option is intended for situations where | ||
309 | ssh-agent offers many different identities. The default is | ||
310 | ``no''. | ||
311 | |||
312 | IdentityFile | ||
313 | Specifies a file from which the user's RSA or DSA authentication | ||
314 | identity is read. The default is ~/.ssh/identity for protocol | ||
315 | version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for protocol ver- | ||
316 | sion 2. Additionally, any identities represented by the authen- | ||
317 | tication agent will be used for authentication. | ||
318 | |||
319 | The file name may use the tilde syntax to refer to a user's home | ||
320 | directory or one of the following escape characters: `%d' (local | ||
321 | user's home directory), `%u' (local user name), `%l' (local host | ||
322 | name), `%h' (remote host name) or `%r' (remote user name). | ||
323 | |||
324 | It is possible to have multiple identity files specified in con- | ||
325 | figuration files; all these identities will be tried in sequence. | ||
326 | |||
327 | KbdInteractiveDevices | ||
328 | Specifies the list of methods to use in keyboard-interactive au- | ||
329 | thentication. Multiple method names must be comma-separated. | ||
330 | The default is to use the server specified list. The methods | ||
331 | available vary depending on what the server supports. For an | ||
332 | OpenSSH server, it may be zero or more of: ``bsdauth'', ``pam'', | ||
333 | and ``skey''. | ||
334 | |||
335 | LocalCommand | ||
336 | Specifies a command to execute on the local machine after suc- | ||
337 | cessfully connecting to the server. The command string extends | ||
338 | to the end of the line, and is executed with /bin/sh. This di- | ||
339 | rective is ignored unless PermitLocalCommand has been enabled. | ||
340 | |||
341 | LocalForward | ||
342 | Specifies that a TCP port on the local machine be forwarded over | ||
343 | the secure channel to the specified host and port from the remote | ||
344 | machine. The first argument must be [bind_address:]port and the | ||
345 | second argument must be host:hostport. IPv6 addresses can be | ||
346 | specified by enclosing addresses in square brackets or by using | ||
347 | an alternative syntax: [bind_address/]port and host/hostport. | ||
348 | Multiple forwardings may be specified, and additional forwardings | ||
349 | can be given on the command line. Only the superuser can forward | ||
350 | privileged ports. By default, the local port is bound in accor- | ||
351 | dance with the GatewayPorts setting. However, an explicit | ||
352 | bind_address may be used to bind the connection to a specific ad- | ||
353 | dress. The bind_address of ``localhost'' indicates that the lis- | ||
354 | tening port be bound for local use only, while an empty address | ||
355 | or `*' indicates that the port should be available from all in- | ||
356 | terfaces. | ||
357 | |||
358 | LogLevel | ||
359 | Gives the verbosity level that is used when logging messages from | ||
360 | ssh(1). The possible values are: QUIET, FATAL, ERROR, INFO, VER- | ||
361 | BOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. | ||
362 | DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify | ||
363 | higher levels of verbose output. | ||
364 | |||
365 | MACs Specifies the MAC (message authentication code) algorithms in or- | ||
366 | der of preference. The MAC algorithm is used in protocol version | ||
367 | 2 for data integrity protection. Multiple algorithms must be | ||
368 | comma-separated. The default is: ``hmac-md5,hmac-sha1,hmac- | ||
369 | ripemd160,hmac-sha1-96,hmac-md5-96''. | ||
370 | |||
371 | NoHostAuthenticationForLocalhost | ||
372 | This option can be used if the home directory is shared across | ||
373 | machines. In this case localhost will refer to a different ma- | ||
374 | chine on each of the machines and the user will get many warnings | ||
375 | about changed host keys. However, this option disables host au- | ||
376 | thentication for localhost. The argument to this keyword must be | ||
377 | ``yes'' or ``no''. The default is to check the host key for lo- | ||
378 | calhost. | ||
379 | |||
380 | NumberOfPasswordPrompts | ||
381 | Specifies the number of password prompts before giving up. The | ||
382 | argument to this keyword must be an integer. The default is 3. | ||
383 | |||
384 | PasswordAuthentication | ||
385 | Specifies whether to use password authentication. The argument | ||
386 | to this keyword must be ``yes'' or ``no''. The default is | ||
387 | ``yes''. | ||
388 | |||
389 | PermitLocalCommand | ||
390 | Allow local command execution via the LocalCommand option or us- | ||
391 | ing the !command escape sequence in ssh(1). The argument must be | ||
392 | ``yes'' or ``no''. The default is ``no''. | ||
393 | |||
394 | Port Specifies the port number to connect on the remote host. The de- | ||
395 | fault is 22. | ||
396 | |||
397 | PreferredAuthentications | ||
398 | Specifies the order in which the client should try protocol 2 au- | ||
399 | thentication methods. This allows a client to prefer one method | ||
400 | (e.g. keyboard-interactive) over another method (e.g. password) | ||
401 | The default for this option is: ``gssapi-with-mic,hostbased, | ||
402 | publickey, keyboard-interactive, password''. | ||
403 | |||
404 | Protocol | ||
405 | Specifies the protocol versions ssh(1) should support in order of | ||
406 | preference. The possible values are `1' and `2'. Multiple ver- | ||
407 | sions must be comma-separated. The default is ``2,1''. This | ||
408 | means that ssh tries version 2 and falls back to version 1 if | ||
409 | version 2 is not available. | ||
410 | |||
411 | ProxyCommand | ||
412 | Specifies the command to use to connect to the server. The com- | ||
413 | mand string extends to the end of the line, and is executed with | ||
414 | /bin/sh. In the command string, `%h' will be substituted by the | ||
415 | host name to connect and `%p' by the port. The command can be | ||
416 | basically anything, and should read from its standard input and | ||
417 | write to its standard output. It should eventually connect an | ||
418 | sshd(8) server running on some machine, or execute sshd -i some- | ||
419 | where. Host key management will be done using the HostName of | ||
420 | the host being connected (defaulting to the name typed by the us- | ||
421 | er). Setting the command to ``none'' disables this option en- | ||
422 | tirely. Note that CheckHostIP is not available for connects with | ||
423 | a proxy command. | ||
424 | |||
425 | This directive is useful in conjunction with nc(1) and its proxy | ||
426 | support. For example, the following directive would connect via | ||
427 | an HTTP proxy at 192.0.2.0: | ||
428 | |||
429 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p | ||
430 | |||
431 | PubkeyAuthentication | ||
432 | Specifies whether to try public key authentication. The argument | ||
433 | to this keyword must be ``yes'' or ``no''. The default is | ||
434 | ``yes''. This option applies to protocol version 2 only. | ||
435 | |||
436 | RekeyLimit | ||
437 | Specifies the maximum amount of data that may be transmitted be- | ||
438 | fore the session key is renegotiated. The argument is the number | ||
439 | of bytes, with an optional suffix of `K', `M', or `G' to indicate | ||
440 | Kilobytes, Megabytes, or Gigabytes, respectively. The default is | ||
441 | between `1G' and `4G', depending on the cipher. This option ap- | ||
442 | plies to protocol version 2 only. | ||
443 | |||
444 | RemoteForward | ||
445 | Specifies that a TCP port on the remote machine be forwarded over | ||
446 | the secure channel to the specified host and port from the local | ||
447 | machine. The first argument must be [bind_address:]port and the | ||
448 | second argument must be host:hostport. IPv6 addresses can be | ||
449 | specified by enclosing addresses in square brackets or by using | ||
450 | an alternative syntax: [bind_address/]port and host/hostport. | ||
451 | Multiple forwardings may be specified, and additional forwardings | ||
452 | can be given on the command line. Only the superuser can forward | ||
453 | privileged ports. | ||
454 | |||
455 | If the bind_address is not specified, the default is to only bind | ||
456 | to loopback addresses. If the bind_address is `*' or an empty | ||
457 | string, then the forwarding is requested to listen on all inter- | ||
458 | faces. Specifying a remote bind_address will only succeed if the | ||
459 | server's GatewayPorts option is enabled (see sshd_config(5)). | ||
460 | |||
461 | RhostsRSAAuthentication | ||
462 | Specifies whether to try rhosts based authentication with RSA | ||
463 | host authentication. The argument must be ``yes'' or ``no''. | ||
464 | The default is ``no''. This option applies to protocol version 1 | ||
465 | only and requires ssh(1) to be setuid root. | ||
466 | |||
467 | RSAAuthentication | ||
468 | Specifies whether to try RSA authentication. The argument to | ||
469 | this keyword must be ``yes'' or ``no''. RSA authentication will | ||
470 | only be attempted if the identity file exists, or an authentica- | ||
471 | tion agent is running. The default is ``yes''. Note that this | ||
472 | option applies to protocol version 1 only. | ||
473 | |||
474 | SendEnv | ||
475 | Specifies what variables from the local environ(7) should be sent | ||
476 | to the server. Note that environment passing is only supported | ||
477 | for protocol 2. The server must also support it, and the server | ||
478 | must be configured to accept these environment variables. Refer | ||
479 | to AcceptEnv in sshd_config(5) for how to configure the server. | ||
480 | Variables are specified by name, which may contain wildcard char- | ||
481 | acters. Multiple environment variables may be separated by | ||
482 | whitespace or spread across multiple SendEnv directives. The de- | ||
483 | fault is not to send any environment variables. | ||
484 | |||
485 | See PATTERNS for more information on patterns. | ||
486 | |||
487 | ServerAliveCountMax | ||
488 | Sets the number of server alive messages (see below) which may be | ||
489 | sent without ssh(1) receiving any messages back from the server. | ||
490 | If this threshold is reached while server alive messages are be- | ||
491 | ing sent, ssh will disconnect from the server, terminating the | ||
492 | session. It is important to note that the use of server alive | ||
493 | messages is very different from TCPKeepAlive (below). The server | ||
494 | alive messages are sent through the encrypted channel and there- | ||
495 | fore will not be spoofable. The TCP keepalive option enabled by | ||
496 | TCPKeepAlive is spoofable. The server alive mechanism is valu- | ||
497 | able when the client or server depend on knowing when a connec- | ||
498 | tion has become inactive. | ||
499 | |||
500 | The default value is 3. If, for example, ServerAliveInterval | ||
501 | (see below) is set to 15 and ServerAliveCountMax is left at the | ||
502 | default, if the server becomes unresponsive, ssh will disconnect | ||
503 | after approximately 45 seconds. This option applies to protocol | ||
504 | version 2 only. | ||
505 | |||
506 | ServerAliveInterval | ||
507 | Sets a timeout interval in seconds after which if no data has | ||
508 | been received from the server, ssh(1) will send a message through | ||
509 | the encrypted channel to request a response from the server. The | ||
510 | default is 0, indicating that these messages will not be sent to | ||
511 | the server. This option applies to protocol version 2 only. | ||
512 | |||
513 | SmartcardDevice | ||
514 | Specifies which smartcard device to use. The argument to this | ||
515 | keyword is the device ssh(1) should use to communicate with a | ||
516 | smartcard used for storing the user's private RSA key. By de- | ||
517 | fault, no device is specified and smartcard support is not acti- | ||
518 | vated. | ||
519 | |||
520 | StrictHostKeyChecking | ||
521 | If this flag is set to ``yes'', ssh(1) will never automatically | ||
522 | add host keys to the ~/.ssh/known_hosts file, and refuses to con- | ||
523 | nect to hosts whose host key has changed. This provides maximum | ||
524 | protection against trojan horse attacks, though it can be annoy- | ||
525 | ing when the /etc/ssh/ssh_known_hosts file is poorly maintained | ||
526 | or when connections to new hosts are frequently made. This op- | ||
527 | tion forces the user to manually add all new hosts. If this flag | ||
528 | is set to ``no'', ssh will automatically add new host keys to the | ||
529 | user known hosts files. If this flag is set to ``ask'', new host | ||
530 | keys will be added to the user known host files only after the | ||
531 | user has confirmed that is what they really want to do, and ssh | ||
532 | will refuse to connect to hosts whose host key has changed. The | ||
533 | host keys of known hosts will be verified automatically in all | ||
534 | cases. The argument must be ``yes'', ``no'', or ``ask''. The | ||
535 | default is ``ask''. | ||
536 | |||
537 | TCPKeepAlive | ||
538 | Specifies whether the system should send TCP keepalive messages | ||
539 | to the other side. If they are sent, death of the connection or | ||
540 | crash of one of the machines will be properly noticed. However, | ||
541 | this means that connections will die if the route is down tem- | ||
542 | porarily, and some people find it annoying. | ||
543 | |||
544 | The default is ``yes'' (to send TCP keepalive messages), and the | ||
545 | client will notice if the network goes down or the remote host | ||
546 | dies. This is important in scripts, and many users want it too. | ||
547 | |||
548 | To disable TCP keepalive messages, the value should be set to | ||
549 | ``no''. | ||
550 | |||
551 | Tunnel Request tun(4) device forwarding between the client and the serv- | ||
552 | er. The argument must be ``yes'', ``point-to-point'' (layer 3), | ||
553 | ``ethernet'' (layer 2), or ``no''. Specifying ``yes'' requests | ||
554 | the default tunnel mode, which is ``point-to-point''. The de- | ||
555 | fault is ``no''. | ||
556 | |||
557 | TunnelDevice | ||
558 | Specifies the tun(4) devices to open on the client (local_tun) | ||
559 | and the server (remote_tun). | ||
560 | |||
561 | The argument must be local_tun[:remote_tun]. The devices may be | ||
562 | specified by numerical ID or the keyword ``any'', which uses the | ||
563 | next available tunnel device. If remote_tun is not specified, it | ||
564 | defaults to ``any''. The default is ``any:any''. | ||
565 | |||
566 | UsePrivilegedPort | ||
567 | Specifies whether to use a privileged port for outgoing connec- | ||
568 | tions. The argument must be ``yes'' or ``no''. The default is | ||
569 | ``no''. If set to ``yes'', ssh(1) must be setuid root. Note | ||
570 | that this option must be set to ``yes'' for | ||
571 | RhostsRSAAuthentication with older servers. | ||
572 | |||
573 | User Specifies the user to log in as. This can be useful when a dif- | ||
574 | ferent user name is used on different machines. This saves the | ||
575 | trouble of having to remember to give the user name on the com- | ||
576 | mand line. | ||
577 | |||
578 | UserKnownHostsFile | ||
579 | Specifies a file to use for the user host key database instead of | ||
580 | ~/.ssh/known_hosts. | ||
581 | |||
582 | VerifyHostKeyDNS | ||
583 | Specifies whether to verify the remote key using DNS and SSHFP | ||
584 | resource records. If this option is set to ``yes'', the client | ||
585 | will implicitly trust keys that match a secure fingerprint from | ||
586 | DNS. Insecure fingerprints will be handled as if this option was | ||
587 | set to ``ask''. If this option is set to ``ask'', information on | ||
588 | fingerprint match will be displayed, but the user will still need | ||
589 | to confirm new host keys according to the StrictHostKeyChecking | ||
590 | option. The argument must be ``yes'', ``no'', or ``ask''. The | ||
591 | default is ``no''. Note that this option applies to protocol | ||
592 | version 2 only. | ||
593 | |||
594 | See also VERIFYING HOST KEYS in ssh(1). | ||
595 | |||
596 | XAuthLocation | ||
597 | Specifies the full pathname of the xauth(1) program. The default | ||
598 | is /usr/X11R6/bin/xauth. | ||
599 | |||
600 | PATTERNS | ||
601 | A pattern consists of zero or more non-whitespace characters, `*' (a | ||
602 | wildcard that matches zero or more characters), or `?' (a wildcard that | ||
603 | matches exactly one character). For example, to specify a set of decla- | ||
604 | rations for any host in the ``.co.uk'' set of domains, the following pat- | ||
605 | tern could be used: | ||
606 | |||
607 | Host *.co.uk | ||
608 | |||
609 | The following pattern would match any host in the 192.168.0.[0-9] network | ||
610 | range: | ||
611 | |||
612 | Host 192.168.0.? | ||
613 | |||
614 | A pattern-list is a comma-separated list of patterns. Patterns within | ||
615 | pattern-lists may be negated by preceding them with an exclamation mark | ||
616 | (`!'). For example, to allow a key to be used from anywhere within an | ||
617 | organisation except from the ``dialup'' pool, the following entry (in au- | ||
618 | thorized_keys) could be used: | ||
619 | |||
620 | from="!*.dialup.example.com,*.example.com" | ||
621 | |||
622 | FILES | ||
623 | ~/.ssh/config | ||
624 | This is the per-user configuration file. The format of this file | ||
625 | is described above. This file is used by the SSH client. Be- | ||
626 | cause of the potential for abuse, this file must have strict per- | ||
627 | missions: read/write for the user, and not accessible by others. | ||
628 | |||
629 | /etc/ssh/ssh_config | ||
630 | Systemwide configuration file. This file provides defaults for | ||
631 | those values that are not specified in the user's configuration | ||
632 | file, and for those users who do not have a configuration file. | ||
633 | This file must be world-readable. | ||
634 | |||
635 | SEE ALSO | ||
636 | ssh(1) | ||
637 | |||
638 | AUTHORS | ||
639 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
640 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
641 | de Raadt and Dug Song removed many bugs, re-added newer features and cre- | ||
642 | ated OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
643 | versions 1.5 and 2.0. | ||
644 | |||
645 | OpenBSD 4.1 September 25, 1999 10 | ||