diff options
author | Colin Watson <cjwatson@debian.org> | 2010-01-01 17:10:56 +0000 |
---|---|---|
committer | Colin Watson <cjwatson@debian.org> | 2010-01-01 17:10:56 +0000 |
commit | 54af7a4ae8d455791a631bdfaade4b64436ae16a (patch) | |
tree | e0ae21993bfc33f09c820b8b2e6b408ad855f4ff /ssh_config.0 | |
parent | faec50b554730338c0e9f34966c11368920b6a78 (diff) | |
parent | ef94e5613d37bcbf880f21ee6094e4b1c7683a4c (diff) |
Import 5.2p1 tarball
Diffstat (limited to 'ssh_config.0')
-rw-r--r-- | ssh_config.0 | 670 |
1 files changed, 670 insertions, 0 deletions
diff --git a/ssh_config.0 b/ssh_config.0 new file mode 100644 index 000000000..e5ded8e31 --- /dev/null +++ b/ssh_config.0 | |||
@@ -0,0 +1,670 @@ | |||
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. If more than one pattern is provided, | ||
44 | they should be separated by whitespace. A single `*' as a pat- | ||
45 | tern can be used to provide global defaults for all hosts. The | ||
46 | host is the hostname argument given on the command line (i.e. the | ||
47 | name is not converted to a canonicalized host name before match- | ||
48 | ing). | ||
49 | |||
50 | See PATTERNS for more information on patterns. | ||
51 | |||
52 | AddressFamily | ||
53 | Specifies which address family to use when connecting. Valid ar- | ||
54 | guments are ``any'', ``inet'' (use IPv4 only), or ``inet6'' (use | ||
55 | IPv6 only). | ||
56 | |||
57 | BatchMode | ||
58 | If set to ``yes'', passphrase/password querying will be disabled. | ||
59 | This option is useful in scripts and other batch jobs where no | ||
60 | user is present to supply the password. The argument must be | ||
61 | ``yes'' or ``no''. The default is ``no''. | ||
62 | |||
63 | BindAddress | ||
64 | Use the specified address on the local machine as the source ad- | ||
65 | dress of the connection. Only useful on systems with more than | ||
66 | one address. Note that this option does not work if | ||
67 | UsePrivilegedPort is set to ``yes''. | ||
68 | |||
69 | ChallengeResponseAuthentication | ||
70 | Specifies whether to use challenge-response authentication. The | ||
71 | argument to this keyword must be ``yes'' or ``no''. The default | ||
72 | is ``yes''. | ||
73 | |||
74 | CheckHostIP | ||
75 | If this flag is set to ``yes'', ssh(1) will additionally check | ||
76 | the host IP address in the known_hosts file. This allows ssh to | ||
77 | detect if a host key changed due to DNS spoofing. If the option | ||
78 | is set to ``no'', the check will not be executed. The default is | ||
79 | ``yes''. | ||
80 | |||
81 | Cipher Specifies the cipher to use for encrypting the session in proto- | ||
82 | col version 1. Currently, ``blowfish'', ``3des'', and ``des'' | ||
83 | are supported. des is only supported in the ssh(1) client for | ||
84 | interoperability with legacy protocol 1 implementations that do | ||
85 | not support the 3des cipher. Its use is strongly discouraged due | ||
86 | to cryptographic weaknesses. The default is ``3des''. | ||
87 | |||
88 | Ciphers | ||
89 | Specifies the ciphers allowed for protocol version 2 in order of | ||
90 | preference. Multiple ciphers must be comma-separated. The sup- | ||
91 | ported ciphers are ``3des-cbc'', ``aes128-cbc'', ``aes192-cbc'', | ||
92 | ``aes256-cbc'', ``aes128-ctr'', ``aes192-ctr'', ``aes256-ctr'', | ||
93 | ``arcfour128'', ``arcfour256'', ``arcfour'', ``blowfish-cbc'', | ||
94 | and ``cast128-cbc''. The default is: | ||
95 | |||
96 | aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, | ||
97 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc, | ||
98 | aes256-cbc,arcfour | ||
99 | |||
100 | ClearAllForwardings | ||
101 | Specifies that all local, remote, and dynamic port forwardings | ||
102 | specified in the configuration files or on the command line be | ||
103 | cleared. This option is primarily useful when used from the | ||
104 | ssh(1) command line to clear port forwardings set in configura- | ||
105 | tion files, and is automatically set by scp(1) and sftp(1). The | ||
106 | argument must be ``yes'' or ``no''. The default is ``no''. | ||
107 | |||
108 | Compression | ||
109 | Specifies whether to use compression. The argument must be | ||
110 | ``yes'' or ``no''. The default is ``no''. | ||
111 | |||
112 | CompressionLevel | ||
113 | Specifies the compression level to use if compression is enabled. | ||
114 | The argument must be an integer from 1 (fast) to 9 (slow, best). | ||
115 | The default level is 6, which is good for most applications. The | ||
116 | meaning of the values is the same as in gzip(1). Note that this | ||
117 | option applies to protocol version 1 only. | ||
118 | |||
119 | ConnectionAttempts | ||
120 | Specifies the number of tries (one per second) to make before ex- | ||
121 | iting. The argument must be an integer. This may be useful in | ||
122 | scripts if the connection sometimes fails. The default is 1. | ||
123 | |||
124 | ConnectTimeout | ||
125 | Specifies the timeout (in seconds) used when connecting to the | ||
126 | SSH server, instead of using the default system TCP timeout. | ||
127 | This value is used only when the target is down or really un- | ||
128 | reachable, not when it refuses the connection. | ||
129 | |||
130 | ControlMaster | ||
131 | Enables the sharing of multiple sessions over a single network | ||
132 | connection. When set to ``yes'', ssh(1) will listen for connec- | ||
133 | tions on a control socket specified using the ControlPath argu- | ||
134 | ment. Additional sessions can connect to this socket using the | ||
135 | same ControlPath with ControlMaster set to ``no'' (the default). | ||
136 | These sessions will try to reuse the master instance's network | ||
137 | connection rather than initiating new ones, but will fall back to | ||
138 | connecting normally if the control socket does not exist, or is | ||
139 | not listening. | ||
140 | |||
141 | Setting this to ``ask'' will cause ssh to listen for control con- | ||
142 | nections, but require confirmation using the SSH_ASKPASS program | ||
143 | before they are accepted (see ssh-add(1) for details). If the | ||
144 | ControlPath cannot be opened, ssh will continue without connect- | ||
145 | ing to a master instance. | ||
146 | |||
147 | X11 and ssh-agent(1) forwarding is supported over these multi- | ||
148 | plexed connections, however the display and agent forwarded will | ||
149 | be the one belonging to the master connection i.e. it is not pos- | ||
150 | sible to forward multiple displays or agents. | ||
151 | |||
152 | Two additional options allow for opportunistic multiplexing: try | ||
153 | to use a master connection but fall back to creating a new one if | ||
154 | one does not already exist. These options are: ``auto'' and | ||
155 | ``autoask''. The latter requires confirmation like the ``ask'' | ||
156 | option. | ||
157 | |||
158 | ControlPath | ||
159 | Specify the path to the control socket used for connection shar- | ||
160 | ing as described in the ControlMaster section above or the string | ||
161 | ``none'' to disable connection sharing. In the path, `%l' will | ||
162 | be substituted by the local host name, `%h' will be substituted | ||
163 | by the target host name, `%p' the port, and `%r' by the remote | ||
164 | login username. It is recommended that any ControlPath used for | ||
165 | opportunistic connection sharing include at least %h, %p, and %r. | ||
166 | This ensures that shared connections are uniquely identified. | ||
167 | |||
168 | DynamicForward | ||
169 | Specifies that a TCP port on the local machine be forwarded over | ||
170 | the secure channel, and the application protocol is then used to | ||
171 | determine where to connect to from the remote machine. | ||
172 | |||
173 | The argument must be [bind_address:]port. IPv6 addresses can be | ||
174 | specified by enclosing addresses in square brackets or by using | ||
175 | an alternative syntax: [bind_address/]port. By default, the lo- | ||
176 | cal port is bound in accordance with the GatewayPorts setting. | ||
177 | However, an explicit bind_address may be used to bind the connec- | ||
178 | tion to a specific address. The bind_address of ``localhost'' | ||
179 | indicates that the listening port be bound for local use only, | ||
180 | while an empty address or `*' indicates that the port should be | ||
181 | available from all interfaces. | ||
182 | |||
183 | Currently the SOCKS4 and SOCKS5 protocols are supported, and | ||
184 | ssh(1) will act as a SOCKS server. Multiple forwardings may be | ||
185 | specified, and additional forwardings can be given on the command | ||
186 | line. Only the superuser can forward privileged ports. | ||
187 | |||
188 | EnableSSHKeysign | ||
189 | Setting this option to ``yes'' in the global client configuration | ||
190 | file /etc/ssh/ssh_config enables the use of the helper program | ||
191 | ssh-keysign(8) during HostbasedAuthentication. The argument must | ||
192 | be ``yes'' or ``no''. The default is ``no''. This option should | ||
193 | be placed in the non-hostspecific section. See ssh-keysign(8) | ||
194 | for more information. | ||
195 | |||
196 | EscapeChar | ||
197 | Sets the escape character (default: `~'). The escape character | ||
198 | can also be set on the command line. The argument should be a | ||
199 | single character, `^' followed by a letter, or ``none'' to dis- | ||
200 | able the escape character entirely (making the connection trans- | ||
201 | parent for binary data). | ||
202 | |||
203 | ExitOnForwardFailure | ||
204 | Specifies whether ssh(1) should terminate the connection if it | ||
205 | cannot set up all requested dynamic, tunnel, local, and remote | ||
206 | port forwardings. The argument must be ``yes'' or ``no''. The | ||
207 | default is ``no''. | ||
208 | |||
209 | ForwardAgent | ||
210 | Specifies whether the connection to the authentication agent (if | ||
211 | any) will be forwarded to the remote machine. The argument must | ||
212 | be ``yes'' or ``no''. The default is ``no''. | ||
213 | |||
214 | Agent forwarding should be enabled with caution. Users with the | ||
215 | ability to bypass file permissions on the remote host (for the | ||
216 | agent's Unix-domain socket) can access the local agent through | ||
217 | the forwarded connection. An attacker cannot obtain key material | ||
218 | from the agent, however they can perform operations on the keys | ||
219 | that enable them to authenticate using the identities loaded into | ||
220 | the agent. | ||
221 | |||
222 | ForwardX11 | ||
223 | Specifies whether X11 connections will be automatically redirect- | ||
224 | ed over the secure channel and DISPLAY set. The argument must be | ||
225 | ``yes'' or ``no''. The default is ``no''. | ||
226 | |||
227 | X11 forwarding should be enabled with caution. Users with the | ||
228 | ability to bypass file permissions on the remote host (for the | ||
229 | user's X11 authorization database) can access the local X11 dis- | ||
230 | play through the forwarded connection. An attacker may then be | ||
231 | able to perform activities such as keystroke monitoring if the | ||
232 | ForwardX11Trusted option is also enabled. | ||
233 | |||
234 | ForwardX11Trusted | ||
235 | If this option is set to ``yes'', remote X11 clients will have | ||
236 | full access to the original X11 display. | ||
237 | |||
238 | If this option is set to ``no'', remote X11 clients will be con- | ||
239 | sidered untrusted and prevented from stealing or tampering with | ||
240 | data belonging to trusted X11 clients. Furthermore, the xauth(1) | ||
241 | token used for the session will be set to expire after 20 min- | ||
242 | utes. Remote clients will be refused access after this time. | ||
243 | |||
244 | The default is ``no''. | ||
245 | |||
246 | See the X11 SECURITY extension specification for full details on | ||
247 | the restrictions imposed on untrusted clients. | ||
248 | |||
249 | GatewayPorts | ||
250 | Specifies whether remote hosts are allowed to connect to local | ||
251 | forwarded ports. By default, ssh(1) binds local port forwardings | ||
252 | to the loopback address. This prevents other remote hosts from | ||
253 | connecting to forwarded ports. GatewayPorts can be used to spec- | ||
254 | ify that ssh should bind local port forwardings to the wildcard | ||
255 | address, thus allowing remote hosts to connect to forwarded | ||
256 | ports. The argument must be ``yes'' or ``no''. The default is | ||
257 | ``no''. | ||
258 | |||
259 | GlobalKnownHostsFile | ||
260 | Specifies a file to use for the global host key database instead | ||
261 | of /etc/ssh/ssh_known_hosts. | ||
262 | |||
263 | GSSAPIAuthentication | ||
264 | Specifies whether user authentication based on GSSAPI is allowed. | ||
265 | The default is ``no''. Note that this option applies to protocol | ||
266 | version 2 only. | ||
267 | |||
268 | GSSAPIDelegateCredentials | ||
269 | Forward (delegate) credentials to the server. The default is | ||
270 | ``no''. Note that this option applies to protocol version 2 on- | ||
271 | ly. | ||
272 | |||
273 | HashKnownHosts | ||
274 | Indicates that ssh(1) should hash host names and addresses when | ||
275 | they are added to ~/.ssh/known_hosts. These hashed names may be | ||
276 | used normally by ssh(1) and sshd(8), but they do not reveal iden- | ||
277 | tifying information should the file's contents be disclosed. The | ||
278 | default is ``no''. Note that existing names and addresses in | ||
279 | known hosts files will not be converted automatically, but may be | ||
280 | manually hashed using ssh-keygen(1). | ||
281 | |||
282 | HostbasedAuthentication | ||
283 | Specifies whether to try rhosts based authentication with public | ||
284 | key authentication. The argument must be ``yes'' or ``no''. The | ||
285 | default is ``no''. This option applies to protocol version 2 on- | ||
286 | ly and is similar to RhostsRSAAuthentication. | ||
287 | |||
288 | HostKeyAlgorithms | ||
289 | Specifies the protocol version 2 host key algorithms that the | ||
290 | client wants to use in order of preference. The default for this | ||
291 | option is: ``ssh-rsa,ssh-dss''. | ||
292 | |||
293 | HostKeyAlias | ||
294 | Specifies an alias that should be used instead of the real host | ||
295 | name when looking up or saving the host key in the host key | ||
296 | database files. This option is useful for tunneling SSH connec- | ||
297 | tions or for multiple servers running on a single host. | ||
298 | |||
299 | HostName | ||
300 | Specifies the real host name to log into. This can be used to | ||
301 | specify nicknames or abbreviations for hosts. The default is the | ||
302 | name given on the command line. Numeric IP addresses are also | ||
303 | permitted (both on the command line and in HostName specifica- | ||
304 | tions). | ||
305 | |||
306 | IdentitiesOnly | ||
307 | Specifies that ssh(1) should only use the authentication identity | ||
308 | files configured in the ssh_config files, even if ssh-agent(1) | ||
309 | offers more identities. The argument to this keyword must be | ||
310 | ``yes'' or ``no''. This option is intended for situations where | ||
311 | ssh-agent offers many different identities. The default is | ||
312 | ``no''. | ||
313 | |||
314 | IdentityFile | ||
315 | Specifies a file from which the user's RSA or DSA authentication | ||
316 | identity is read. The default is ~/.ssh/identity for protocol | ||
317 | version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for protocol ver- | ||
318 | sion 2. Additionally, any identities represented by the authen- | ||
319 | tication agent will be used for authentication. | ||
320 | |||
321 | The file name may use the tilde syntax to refer to a user's home | ||
322 | directory or one of the following escape characters: `%d' (local | ||
323 | user's home directory), `%u' (local user name), `%l' (local host | ||
324 | name), `%h' (remote host name) or `%r' (remote user name). | ||
325 | |||
326 | It is possible to have multiple identity files specified in con- | ||
327 | figuration files; all these identities will be tried in sequence. | ||
328 | |||
329 | KbdInteractiveAuthentication | ||
330 | Specifies whether to use keyboard-interactive authentication. | ||
331 | The argument to this keyword must be ``yes'' or ``no''. The de- | ||
332 | fault is ``yes''. | ||
333 | |||
334 | KbdInteractiveDevices | ||
335 | Specifies the list of methods to use in keyboard-interactive au- | ||
336 | thentication. Multiple method names must be comma-separated. | ||
337 | The default is to use the server specified list. The methods | ||
338 | available vary depending on what the server supports. For an | ||
339 | OpenSSH server, it may be zero or more of: ``bsdauth'', ``pam'', | ||
340 | and ``skey''. | ||
341 | |||
342 | LocalCommand | ||
343 | Specifies a command to execute on the local machine after suc- | ||
344 | cessfully connecting to the server. The command string extends | ||
345 | to the end of the line, and is executed with the user's shell. | ||
346 | The following escape character substitutions will be performed: | ||
347 | `%d' (local user's home directory), `%h' (remote host name), `%l' | ||
348 | (local host name), `%n' (host name as provided on the command | ||
349 | line), `%p' (remote port), `%r' (remote user name) or `%u' (local | ||
350 | user name). This directive is ignored unless PermitLocalCommand | ||
351 | has been enabled. | ||
352 | |||
353 | LocalForward | ||
354 | Specifies that a TCP port on the local machine be forwarded over | ||
355 | the secure channel to the specified host and port from the remote | ||
356 | machine. The first argument must be [bind_address:]port and the | ||
357 | second argument must be host:hostport. IPv6 addresses can be | ||
358 | specified by enclosing addresses in square brackets or by using | ||
359 | an alternative syntax: [bind_address/]port and host/hostport. | ||
360 | Multiple forwardings may be specified, and additional forwardings | ||
361 | can be given on the command line. Only the superuser can forward | ||
362 | privileged ports. By default, the local port is bound in accor- | ||
363 | dance with the GatewayPorts setting. However, an explicit | ||
364 | bind_address may be used to bind the connection to a specific ad- | ||
365 | dress. The bind_address of ``localhost'' indicates that the lis- | ||
366 | tening port be bound for local use only, while an empty address | ||
367 | or `*' indicates that the port should be available from all in- | ||
368 | terfaces. | ||
369 | |||
370 | LogLevel | ||
371 | Gives the verbosity level that is used when logging messages from | ||
372 | ssh(1). The possible values are: QUIET, FATAL, ERROR, INFO, VER- | ||
373 | BOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. | ||
374 | DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify | ||
375 | higher levels of verbose output. | ||
376 | |||
377 | MACs Specifies the MAC (message authentication code) algorithms in or- | ||
378 | der of preference. The MAC algorithm is used in protocol version | ||
379 | 2 for data integrity protection. Multiple algorithms must be | ||
380 | comma-separated. The default is: | ||
381 | |||
382 | hmac-md5,hmac-sha1,umac-64@openssh.com, | ||
383 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 | ||
384 | |||
385 | NoHostAuthenticationForLocalhost | ||
386 | This option can be used if the home directory is shared across | ||
387 | machines. In this case localhost will refer to a different ma- | ||
388 | chine on each of the machines and the user will get many warnings | ||
389 | about changed host keys. However, this option disables host au- | ||
390 | thentication for localhost. The argument to this keyword must be | ||
391 | ``yes'' or ``no''. The default is to check the host key for lo- | ||
392 | calhost. | ||
393 | |||
394 | NumberOfPasswordPrompts | ||
395 | Specifies the number of password prompts before giving up. The | ||
396 | argument to this keyword must be an integer. The default is 3. | ||
397 | |||
398 | PasswordAuthentication | ||
399 | Specifies whether to use password authentication. The argument | ||
400 | to this keyword must be ``yes'' or ``no''. The default is | ||
401 | ``yes''. | ||
402 | |||
403 | PermitLocalCommand | ||
404 | Allow local command execution via the LocalCommand option or us- | ||
405 | ing the !command escape sequence in ssh(1). The argument must be | ||
406 | ``yes'' or ``no''. The default is ``no''. | ||
407 | |||
408 | Port Specifies the port number to connect on the remote host. The de- | ||
409 | fault is 22. | ||
410 | |||
411 | PreferredAuthentications | ||
412 | Specifies the order in which the client should try protocol 2 au- | ||
413 | thentication methods. This allows a client to prefer one method | ||
414 | (e.g. keyboard-interactive) over another method (e.g. password) | ||
415 | The default for this option is: ``gssapi-with-mic,hostbased, | ||
416 | publickey, keyboard-interactive, password''. | ||
417 | |||
418 | Protocol | ||
419 | Specifies the protocol versions ssh(1) should support in order of | ||
420 | preference. The possible values are `1' and `2'. Multiple ver- | ||
421 | sions must be comma-separated. The default is ``2,1''. This | ||
422 | means that ssh tries version 2 and falls back to version 1 if | ||
423 | version 2 is not available. | ||
424 | |||
425 | ProxyCommand | ||
426 | Specifies the command to use to connect to the server. The com- | ||
427 | mand string extends to the end of the line, and is executed with | ||
428 | the user's shell. In the command string, `%h' will be substitut- | ||
429 | ed by the host name to connect and `%p' by the port. The command | ||
430 | can be basically anything, and should read from its standard in- | ||
431 | put and write to its standard output. It should eventually con- | ||
432 | nect an sshd(8) server running on some machine, or execute sshd | ||
433 | -i somewhere. Host key management will be done using the Host- | ||
434 | Name of the host being connected (defaulting to the name typed by | ||
435 | the user). Setting the command to ``none'' disables this option | ||
436 | entirely. Note that CheckHostIP is not available for connects | ||
437 | with a proxy command. | ||
438 | |||
439 | This directive is useful in conjunction with nc(1) and its proxy | ||
440 | support. For example, the following directive would connect via | ||
441 | an HTTP proxy at 192.0.2.0: | ||
442 | |||
443 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p | ||
444 | |||
445 | PubkeyAuthentication | ||
446 | Specifies whether to try public key authentication. The argument | ||
447 | to this keyword must be ``yes'' or ``no''. The default is | ||
448 | ``yes''. This option applies to protocol version 2 only. | ||
449 | |||
450 | RekeyLimit | ||
451 | Specifies the maximum amount of data that may be transmitted be- | ||
452 | fore the session key is renegotiated. The argument is the number | ||
453 | of bytes, with an optional suffix of `K', `M', or `G' to indicate | ||
454 | Kilobytes, Megabytes, or Gigabytes, respectively. The default is | ||
455 | between `1G' and `4G', depending on the cipher. This option ap- | ||
456 | plies to protocol version 2 only. | ||
457 | |||
458 | RemoteForward | ||
459 | Specifies that a TCP port on the remote machine be forwarded over | ||
460 | the secure channel to the specified host and port from the local | ||
461 | machine. The first argument must be [bind_address:]port and the | ||
462 | second argument must be host:hostport. IPv6 addresses can be | ||
463 | specified by enclosing addresses in square brackets or by using | ||
464 | an alternative syntax: [bind_address/]port and host/hostport. | ||
465 | Multiple forwardings may be specified, and additional forwardings | ||
466 | can be given on the command line. Privileged ports can be for- | ||
467 | warded only when logging in as root on the remote machine. | ||
468 | |||
469 | If the port argument is `0', the listen port will be dynamically | ||
470 | allocated on the server and reported to the client at run time. | ||
471 | |||
472 | If the bind_address is not specified, the default is to only bind | ||
473 | to loopback addresses. If the bind_address is `*' or an empty | ||
474 | string, then the forwarding is requested to listen on all inter- | ||
475 | faces. Specifying a remote bind_address will only succeed if the | ||
476 | server's GatewayPorts option is enabled (see sshd_config(5)). | ||
477 | |||
478 | RhostsRSAAuthentication | ||
479 | Specifies whether to try rhosts based authentication with RSA | ||
480 | host authentication. The argument must be ``yes'' or ``no''. | ||
481 | The default is ``no''. This option applies to protocol version 1 | ||
482 | only and requires ssh(1) to be setuid root. | ||
483 | |||
484 | RSAAuthentication | ||
485 | Specifies whether to try RSA authentication. The argument to | ||
486 | this keyword must be ``yes'' or ``no''. RSA authentication will | ||
487 | only be attempted if the identity file exists, or an authentica- | ||
488 | tion agent is running. The default is ``yes''. Note that this | ||
489 | option applies to protocol version 1 only. | ||
490 | |||
491 | SendEnv | ||
492 | Specifies what variables from the local environ(7) should be sent | ||
493 | to the server. Note that environment passing is only supported | ||
494 | for protocol 2. The server must also support it, and the server | ||
495 | must be configured to accept these environment variables. Refer | ||
496 | to AcceptEnv in sshd_config(5) for how to configure the server. | ||
497 | Variables are specified by name, which may contain wildcard char- | ||
498 | acters. Multiple environment variables may be separated by | ||
499 | whitespace or spread across multiple SendEnv directives. The de- | ||
500 | fault is not to send any environment variables. | ||
501 | |||
502 | See PATTERNS for more information on patterns. | ||
503 | |||
504 | ServerAliveCountMax | ||
505 | Sets the number of server alive messages (see below) which may be | ||
506 | sent without ssh(1) receiving any messages back from the server. | ||
507 | If this threshold is reached while server alive messages are be- | ||
508 | ing sent, ssh will disconnect from the server, terminating the | ||
509 | session. It is important to note that the use of server alive | ||
510 | messages is very different from TCPKeepAlive (below). The server | ||
511 | alive messages are sent through the encrypted channel and there- | ||
512 | fore will not be spoofable. The TCP keepalive option enabled by | ||
513 | TCPKeepAlive is spoofable. The server alive mechanism is valu- | ||
514 | able when the client or server depend on knowing when a connec- | ||
515 | tion has become inactive. | ||
516 | |||
517 | The default value is 3. If, for example, ServerAliveInterval | ||
518 | (see below) is set to 15 and ServerAliveCountMax is left at the | ||
519 | default, if the server becomes unresponsive, ssh will disconnect | ||
520 | after approximately 45 seconds. This option applies to protocol | ||
521 | version 2 only. | ||
522 | |||
523 | ServerAliveInterval | ||
524 | Sets a timeout interval in seconds after which if no data has | ||
525 | been received from the server, ssh(1) will send a message through | ||
526 | the encrypted channel to request a response from the server. The | ||
527 | default is 0, indicating that these messages will not be sent to | ||
528 | the server. This option applies to protocol version 2 only. | ||
529 | |||
530 | SmartcardDevice | ||
531 | Specifies which smartcard device to use. The argument to this | ||
532 | keyword is the device ssh(1) should use to communicate with a | ||
533 | smartcard used for storing the user's private RSA key. By de- | ||
534 | fault, no device is specified and smartcard support is not acti- | ||
535 | vated. | ||
536 | |||
537 | StrictHostKeyChecking | ||
538 | If this flag is set to ``yes'', ssh(1) will never automatically | ||
539 | add host keys to the ~/.ssh/known_hosts file, and refuses to con- | ||
540 | nect to hosts whose host key has changed. This provides maximum | ||
541 | protection against trojan horse attacks, though it can be annoy- | ||
542 | ing when the /etc/ssh/ssh_known_hosts file is poorly maintained | ||
543 | or when connections to new hosts are frequently made. This op- | ||
544 | tion forces the user to manually add all new hosts. If this flag | ||
545 | is set to ``no'', ssh will automatically add new host keys to the | ||
546 | user known hosts files. If this flag is set to ``ask'', new host | ||
547 | keys will be added to the user known host files only after the | ||
548 | user has confirmed that is what they really want to do, and ssh | ||
549 | will refuse to connect to hosts whose host key has changed. The | ||
550 | host keys of known hosts will be verified automatically in all | ||
551 | cases. The argument must be ``yes'', ``no'', or ``ask''. The | ||
552 | default is ``ask''. | ||
553 | |||
554 | TCPKeepAlive | ||
555 | Specifies whether the system should send TCP keepalive messages | ||
556 | to the other side. If they are sent, death of the connection or | ||
557 | crash of one of the machines will be properly noticed. However, | ||
558 | this means that connections will die if the route is down tem- | ||
559 | porarily, and some people find it annoying. | ||
560 | |||
561 | The default is ``yes'' (to send TCP keepalive messages), and the | ||
562 | client will notice if the network goes down or the remote host | ||
563 | dies. This is important in scripts, and many users want it too. | ||
564 | |||
565 | To disable TCP keepalive messages, the value should be set to | ||
566 | ``no''. | ||
567 | |||
568 | Tunnel Request tun(4) device forwarding between the client and the serv- | ||
569 | er. The argument must be ``yes'', ``point-to-point'' (layer 3), | ||
570 | ``ethernet'' (layer 2), or ``no''. Specifying ``yes'' requests | ||
571 | the default tunnel mode, which is ``point-to-point''. The de- | ||
572 | fault is ``no''. | ||
573 | |||
574 | TunnelDevice | ||
575 | Specifies the tun(4) devices to open on the client (local_tun) | ||
576 | and the server (remote_tun). | ||
577 | |||
578 | The argument must be local_tun[:remote_tun]. The devices may be | ||
579 | specified by numerical ID or the keyword ``any'', which uses the | ||
580 | next available tunnel device. If remote_tun is not specified, it | ||
581 | defaults to ``any''. The default is ``any:any''. | ||
582 | |||
583 | UsePrivilegedPort | ||
584 | Specifies whether to use a privileged port for outgoing connec- | ||
585 | tions. The argument must be ``yes'' or ``no''. The default is | ||
586 | ``no''. If set to ``yes'', ssh(1) must be setuid root. Note | ||
587 | that this option must be set to ``yes'' for | ||
588 | RhostsRSAAuthentication with older servers. | ||
589 | |||
590 | User Specifies the user to log in as. This can be useful when a dif- | ||
591 | ferent user name is used on different machines. This saves the | ||
592 | trouble of having to remember to give the user name on the com- | ||
593 | mand line. | ||
594 | |||
595 | UserKnownHostsFile | ||
596 | Specifies a file to use for the user host key database instead of | ||
597 | ~/.ssh/known_hosts. | ||
598 | |||
599 | VerifyHostKeyDNS | ||
600 | Specifies whether to verify the remote key using DNS and SSHFP | ||
601 | resource records. If this option is set to ``yes'', the client | ||
602 | will implicitly trust keys that match a secure fingerprint from | ||
603 | DNS. Insecure fingerprints will be handled as if this option was | ||
604 | set to ``ask''. If this option is set to ``ask'', information on | ||
605 | fingerprint match will be displayed, but the user will still need | ||
606 | to confirm new host keys according to the StrictHostKeyChecking | ||
607 | option. The argument must be ``yes'', ``no'', or ``ask''. The | ||
608 | default is ``no''. Note that this option applies to protocol | ||
609 | version 2 only. | ||
610 | |||
611 | See also VERIFYING HOST KEYS in ssh(1). | ||
612 | |||
613 | VisualHostKey | ||
614 | If this flag is set to ``yes'', an ASCII art representation of | ||
615 | the remote host key fingerprint is printed in addition to the hex | ||
616 | fingerprint string at login and for unknown host keys. If this | ||
617 | flag is set to ``no'', no fingerprint strings are printed at lo- | ||
618 | gin and only the hex fingerprint string will be printed for un- | ||
619 | known host keys. The default is ``no''. | ||
620 | |||
621 | XAuthLocation | ||
622 | Specifies the full pathname of the xauth(1) program. The default | ||
623 | is /usr/X11R6/bin/xauth. | ||
624 | |||
625 | PATTERNS | ||
626 | A pattern consists of zero or more non-whitespace characters, `*' (a | ||
627 | wildcard that matches zero or more characters), or `?' (a wildcard that | ||
628 | matches exactly one character). For example, to specify a set of decla- | ||
629 | rations for any host in the ``.co.uk'' set of domains, the following pat- | ||
630 | tern could be used: | ||
631 | |||
632 | Host *.co.uk | ||
633 | |||
634 | The following pattern would match any host in the 192.168.0.[0-9] network | ||
635 | range: | ||
636 | |||
637 | Host 192.168.0.? | ||
638 | |||
639 | A pattern-list is a comma-separated list of patterns. Patterns within | ||
640 | pattern-lists may be negated by preceding them with an exclamation mark | ||
641 | (`!'). For example, to allow a key to be used from anywhere within an | ||
642 | organisation except from the ``dialup'' pool, the following entry (in au- | ||
643 | thorized_keys) could be used: | ||
644 | |||
645 | from="!*.dialup.example.com,*.example.com" | ||
646 | |||
647 | FILES | ||
648 | ~/.ssh/config | ||
649 | This is the per-user configuration file. The format of this file | ||
650 | is described above. This file is used by the SSH client. Be- | ||
651 | cause of the potential for abuse, this file must have strict per- | ||
652 | missions: read/write for the user, and not accessible by others. | ||
653 | |||
654 | /etc/ssh/ssh_config | ||
655 | Systemwide configuration file. This file provides defaults for | ||
656 | those values that are not specified in the user's configuration | ||
657 | file, and for those users who do not have a configuration file. | ||
658 | This file must be world-readable. | ||
659 | |||
660 | SEE ALSO | ||
661 | ssh(1) | ||
662 | |||
663 | AUTHORS | ||
664 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
665 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
666 | de Raadt and Dug Song removed many bugs, re-added newer features and cre- | ||
667 | ated OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
668 | versions 1.5 and 2.0. | ||
669 | |||
670 | OpenBSD 4.5 February 22, 2009 11 | ||