1SSH_CONFIG(5) BSD File Formats Manual SSH_CONFIG(5)
2
4 ssh_config — OpenSSH SSH client configuration files
5
7 ~/.ssh/config
8 /etc/ssh/ssh_config
9
11 ssh(1) obtains configuration data from the following sources in the fol‐
12 lowing order:
13 1. command-line options
15 2. user's configuration file (~/.ssh/config)
16 3. system-wide configuration file (/etc/ssh/ssh_config)
17 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 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 The configuration file has the following format:
29 Empty lines and lines starting with ‘#’ are comments. Otherwise a line
31 is of the format “keyword arguments”. Configuration options may be sepa‐
32 rated by whitespace or optional whitespace and exactly one ‘=’; the lat‐
33 ter format is useful to avoid the need to quote whitespace when specify‐
34 ing configuration options using the ssh, scp, and sftp -o option. Argu‐
35 ments may optionally be enclosed in double quotes (") in order to repre‐
36 sent arguments containing spaces.
37 The possible keywords and their meanings are as follows (note that key‐
39 words are case-insensitive and arguments are case-sensitive):
40 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 See PATTERNS for more information on patterns.
49 AddressFamily
51 Specifies which address family to use when connecting. Valid
52 arguments are “any”, “inet” (use IPv4 only), or “inet6” (use IPv6
53 only).
54 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 BindAddress
62 Use the specified address on the local machine as the source
63 address 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 ChallengeResponseAuthentication
68 Specifies whether to use challenge-response authentication. The
69 argument to this keyword must be “yes” or “no”. The default is
70 “yes”.
71 CheckHostIP
73 If this flag is set to “yes”, ssh(1) will additionally check the
74 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 Cipher Specifies the cipher to use for encrypting the session in proto‐
80 col version 1. Currently, “blowfish”, “3des”, and “des” are sup‐
81 ported. des is only supported in the ssh(1) client for interop‐
82 erability with legacy protocol 1 implementations that do not sup‐
83 port the 3des cipher. Its use is strongly discouraged due to
84 cryptographic weaknesses. The default is “3des”.
85 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”, and
92 “cast128-cbc”. The default is:
93 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,
95 arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr,
96 aes192-ctr,aes256-ctr
97 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 Compression
107 Specifies whether to use compression. The argument must be “yes”
108 or “no”. The default is “no”.
109 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 ConnectionAttempts
118 Specifies the number of tries (one per second) to make before
119 exiting. The argument must be an integer. This may be useful in
120 scripts if the connection sometimes fails. The default is 1.
121 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
126 unreachable, not when it refuses the connection.
127 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 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 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 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 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 be
160 substituted by the local host name, ‘%h’ will be substituted by
161 the target host name, ‘%p’ the port, and ‘%r’ by the remote login
162 username. It is recommended that any ControlPath used for oppor‐
163 tunistic connection sharing include at least %h, %p, and %r.
164 This ensures that shared connections are uniquely identified.
165 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 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
174 local 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 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 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 be
191 placed in the non-hostspecific section. See ssh-keysign(8) for
192 more information.
193 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 disable
198 the escape character entirely (making the connection transparent
199 for binary data).
200 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 is
205 “no”.
206 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 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 ForwardX11
221 Specifies whether X11 connections will be automatically redi‐
222 rected over the secure channel and DISPLAY set. The argument
223 must be “yes” or “no”. The default is “no”.
224 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 ForwardX11Trusted
233 If this option is set to “yes”, remote X11 clients will have full
234 access to the original X11 display.
235 If this option is set to “no”, remote X11 clients will be consid‐
237 ered untrusted and prevented from stealing or tampering with data
238 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 The default is “no”.
243 See the X11 SECURITY extension specification for full details on
245 the restrictions imposed on untrusted clients.
246 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 “no”.
255 GlobalKnownHostsFile
257 Specifies a file to use for the global host key database instead
258 of /etc/ssh/ssh_known_hosts.
259 GSSAPIAuthentication
261 Specifies whether user authentication based on GSSAPI is allowed.
262 The default is “no”. Note that this option applies to protocol
263 version 2 only.
264 GSSAPIDelegateCredentials
266 Forward (delegate) credentials to the server. The default is
267 “no”. Note that this option applies to protocol version 2 only.
268 HashKnownHosts
270 Indicates that ssh(1) should hash host names and addresses when
271 they are added to ~/.ssh/known_hosts. These hashed names may be
272 used normally by ssh(1) and sshd(8), but they do not reveal iden‐
273 tifying information should the file's contents be disclosed. The
274 default is “no”. Note that existing names and addresses in known
275 hosts files will not be converted automatically, but may be manu‐
276 ally hashed using ssh-keygen(1).
277 HostbasedAuthentication
279 Specifies whether to try rhosts based authentication with public
280 key authentication. The argument must be “yes” or “no”. The
281 default is “no”. This option applies to protocol version 2 only
282 and is similar to RhostsRSAAuthentication.
283 HostKeyAlgorithms
285 Specifies the protocol version 2 host key algorithms that the
286 client wants to use in order of preference. The default for this
287 option is: “ssh-rsa,ssh-dss”.
288 HostKeyAlias
290 Specifies an alias that should be used instead of the real host
291 name when looking up or saving the host key in the host key data‐
292 base files. This option is useful for tunneling SSH connections
293 or for multiple servers running on a single host.
294 HostName
296 Specifies the real host name to log into. This can be used to
297 specify nicknames or abbreviations for hosts. The default is the
298 name given on the command line. Numeric IP addresses are also
299 permitted (both on the command line and in HostName specifica‐
300 tions).
301 IdentitiesOnly
303 Specifies that ssh(1) should only use the authentication identity
304 files configured in the ssh_config files, even if ssh-agent(1)
305 offers more identities. The argument to this keyword must be
306 “yes” or “no”. This option is intended for situations where ssh-
307 agent offers many different identities. The default is “no”.
308 IdentityFile
310 Specifies a file from which the user's RSA or DSA authentication
311 identity is read. The default is ~/.ssh/identity for protocol
312 version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for protocol ver‐
313 sion 2. Additionally, any identities represented by the authen‐
314 tication agent will be used for authentication.
315 The file name may use the tilde syntax to refer to a user's home
317 directory or one of the following escape characters: ‘%d’ (local
318 user's home directory), ‘%u’ (local user name), ‘%l’ (local host
319 name), ‘%h’ (remote host name) or ‘%r’ (remote user name).
320 It is possible to have multiple identity files specified in con‐
322 figuration files; all these identities will be tried in sequence.
323 KbdInteractiveDevices
325 Specifies the list of methods to use in keyboard-interactive
326 authentication. Multiple method names must be comma-separated.
327 The default is to use the server specified list. The methods
328 available vary depending on what the server supports. For an
329 OpenSSH server, it may be zero or more of: “bsdauth”, “pam”, and
330 “skey”.
331 LocalCommand
333 Specifies a command to execute on the local machine after suc‐
334 cessfully connecting to the server. The command string extends
335 to the end of the line, and is executed with /bin/sh. This
336 directive is ignored unless PermitLocalCommand has been enabled.
337 LocalForward
339 Specifies that a TCP port on the local machine be forwarded over
340 the secure channel to the specified host and port from the remote
341 machine. The first argument must be [bind_address:]port and the
342 second argument must be host:hostport. IPv6 addresses can be
343 specified by enclosing addresses in square brackets or by using
344 an alternative syntax: [bind_address/]port and host/hostport.
345 Multiple forwardings may be specified, and additional forwardings
346 can be given on the command line. Only the superuser can forward
347 privileged ports. By default, the local port is bound in accor‐
348 dance with the GatewayPorts setting. However, an explicit
349 bind_address may be used to bind the connection to a specific
350 address. The bind_address of “localhost” indicates that the lis‐
351 tening port be bound for local use only, while an empty address
352 or ‘*’ indicates that the port should be available from all
353 interfaces.
354 LogLevel
356 Gives the verbosity level that is used when logging messages from
357 ssh(1). The possible values are: QUIET, FATAL, ERROR, INFO, VER‐
358 BOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO.
359 DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify
360 higher levels of verbose output.
361 MACs Specifies the MAC (message authentication code) algorithms in
363 order of preference. The MAC algorithm is used in protocol ver‐
364 sion 2 for data integrity protection. Multiple algorithms must
365 be comma-separated. The default is:
366 “hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96”.
367 NoHostAuthenticationForLocalhost
369 This option can be used if the home directory is shared across
370 machines. In this case localhost will refer to a different
371 machine on each of the machines and the user will get many warn‐
372 ings about changed host keys. However, this option disables host
373 authentication for localhost. The argument to this keyword must
374 be “yes” or “no”. The default is to check the host key for
375 localhost.
376 NumberOfPasswordPrompts
378 Specifies the number of password prompts before giving up. The
379 argument to this keyword must be an integer. The default is 3.
380 PasswordAuthentication
382 Specifies whether to use password authentication. The argument
383 to this keyword must be “yes” or “no”. The default is “yes”.
384 PermitLocalCommand
386 Allow local command execution via the LocalCommand option or
387 using the !command escape sequence in ssh(1). The argument must
388 be “yes” or “no”. The default is “no”.
389 Port Specifies the port number to connect on the remote host. The
391 default is 22.
392 PreferredAuthentications
394 Specifies the order in which the client should try protocol 2
395 authentication methods. This allows a client to prefer one
396 method (e.g. keyboard-interactive) over another method (e.g.
397 password) The default for this option is: “gssapi-with-mic,
398 hostbased, publickey, keyboard-interactive, password”.
399 Protocol
401 Specifies the protocol versions ssh(1) should support in order of
402 preference. The possible values are ‘1’ and ‘2’. Multiple ver‐
403 sions must be comma-separated. The default is “2,1”. This means
404 that ssh tries version 2 and falls back to version 1 if version 2
405 is not available.
406 ProxyCommand
408 Specifies the command to use to connect to the server. The com‐
409 mand string extends to the end of the line, and is executed with
410 /bin/sh. In the command string, ‘%h’ will be substituted by the
411 host name to connect and ‘%p’ by the port. The command can be
412 basically anything, and should read from its standard input and
413 write to its standard output. It should eventually connect an
414 sshd(8) server running on some machine, or execute sshd -i some‐
415 where. Host key management will be done using the HostName of
416 the host being connected (defaulting to the name typed by the
417 user). Setting the command to “none” disables this option
418 entirely. Note that CheckHostIP is not available for connects
419 with a proxy command.
420 This directive is useful in conjunction with nc(1) and its proxy
422 support. For example, the following directive would connect via
423 an HTTP proxy at 192.0.2.0:
424 ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p
426 PubkeyAuthentication
428 Specifies whether to try public key authentication. The argument
429 to this keyword must be “yes” or “no”. The default is “yes”.
430 This option applies to protocol version 2 only.
431 RekeyLimit
433 Specifies the maximum amount of data that may be transmitted
434 before the session key is renegotiated. The argument is the num‐
435 ber of bytes, with an optional suffix of ‘K’, ‘M’, or ‘G’ to
436 indicate Kilobytes, Megabytes, or Gigabytes, respectively. The
437 default is between ‘1G’ and ‘4G’, depending on the cipher. This
438 option applies to protocol version 2 only.
439 RemoteForward
441 Specifies that a TCP port on the remote machine be forwarded over
442 the secure channel to the specified host and port from the local
443 machine. The first argument must be [bind_address:]port and the
444 second argument must be host:hostport. IPv6 addresses can be
445 specified by enclosing addresses in square brackets or by using
446 an alternative syntax: [bind_address/]port and host/hostport.
447 Multiple forwardings may be specified, and additional forwardings
448 can be given on the command line. Only the superuser can forward
449 privileged ports.
450 If the bind_address is not specified, the default is to only bind
452 to loopback addresses. If the bind_address is ‘*’ or an empty
453 string, then the forwarding is requested to listen on all inter‐
454 faces. Specifying a remote bind_address will only succeed if the
455 server's GatewayPorts option is enabled (see sshd_config(5)).
456 RhostsRSAAuthentication
458 Specifies whether to try rhosts based authentication with RSA
459 host authentication. The argument must be “yes” or “no”. The
460 default is “no”. This option applies to protocol version 1 only
461 and requires ssh(1) to be setuid root.
462 RSAAuthentication
464 Specifies whether to try RSA authentication. The argument to
465 this keyword must be “yes” or “no”. RSA authentication will only
466 be attempted if the identity file exists, or an authentication
467 agent is running. The default is “yes”. Note that this option
468 applies to protocol version 1 only.
469 SendEnv
471 Specifies what variables from the local environ(7) should be sent
472 to the server. Note that environment passing is only supported
473 for protocol 2. The server must also support it, and the server
474 must be configured to accept these environment variables. Refer
475 to AcceptEnv in sshd_config(5) for how to configure the server.
476 Variables are specified by name, which may contain wildcard char‐
477 acters. Multiple environment variables may be separated by
478 whitespace or spread across multiple SendEnv directives. The
479 default is not to send any environment variables.
480 See PATTERNS for more information on patterns.
482 ServerAliveCountMax
484 Sets the number of server alive messages (see below) which may be
485 sent without ssh(1) receiving any messages back from the server.
486 If this threshold is reached while server alive messages are
487 being sent, ssh will disconnect from the server, terminating the
488 session. It is important to note that the use of server alive
489 messages is very different from TCPKeepAlive (below). The server
490 alive messages are sent through the encrypted channel and there‐
491 fore will not be spoofable. The TCP keepalive option enabled by
492 TCPKeepAlive is spoofable. The server alive mechanism is valu‐
493 able when the client or server depend on knowing when a connec‐
494 tion has become inactive.
495 The default value is 3. If, for example, ServerAliveInterval
497 (see below) is set to 15 and ServerAliveCountMax is left at the
498 default, if the server becomes unresponsive, ssh will disconnect
499 after approximately 45 seconds. This option applies to protocol
500 version 2 only.
501 ServerAliveInterval
503 Sets a timeout interval in seconds after which if no data has
504 been received from the server, ssh(1) will send a message through
505 the encrypted channel to request a response from the server. The
506 default is 0, indicating that these messages will not be sent to
507 the server. This option applies to protocol version 2 only.
508 SmartcardDevice
510 Specifies which smartcard device to use. The argument to this
511 keyword is the device ssh(1) should use to communicate with a
512 smartcard used for storing the user's private RSA key. By
513 default, no device is specified and smartcard support is not
514 activated.
515 StrictHostKeyChecking
517 If this flag is set to “yes”, ssh(1) will never automatically add
518 host keys to the ~/.ssh/known_hosts file, and refuses to connect
519 to hosts whose host key has changed. This provides maximum pro‐
520 tection against trojan horse attacks, though it can be annoying
521 when the /etc/ssh/ssh_known_hosts file is poorly maintained or
522 when connections to new hosts are frequently made. This option
523 forces the user to manually add all new hosts. If this flag is
524 set to “no”, ssh will automatically add new host keys to the user
525 known hosts files. If this flag is set to “ask”, new host keys
526 will be added to the user known host files only after the user
527 has confirmed that is what they really want to do, and ssh will
528 refuse to connect to hosts whose host key has changed. The host
529 keys of known hosts will be verified automatically in all cases.
530 The argument must be “yes”, “no”, or “ask”. The default is
531 “ask”.
532 TCPKeepAlive
534 Specifies whether the system should send TCP keepalive messages
535 to the other side. If they are sent, death of the connection or
536 crash of one of the machines will be properly noticed. However,
537 this means that connections will die if the route is down tempo‐
538 rarily, and some people find it annoying.
539 The default is “yes” (to send TCP keepalive messages), and the
541 client will notice if the network goes down or the remote host
542 dies. This is important in scripts, and many users want it too.
543 To disable TCP keepalive messages, the value should be set to
545 “no”.
546 Tunnel Request tun(4) device forwarding between the client and the
548 server. The argument must be “yes”, “point-to-point” (layer 3),
549 “ethernet” (layer 2), or “no”. Specifying “yes” requests the
550 default tunnel mode, which is “point-to-point”. The default is
551 “no”.
552 TunnelDevice
554 Specifies the tun(4) devices to open on the client (local_tun)
555 and the server (remote_tun).
556 The argument must be local_tun[:remote_tun]. The devices may be
558 specified by numerical ID or the keyword “any”, which uses the
559 next available tunnel device. If remote_tun is not specified, it
560 defaults to “any”. The default is “any:any”.
561 UsePrivilegedPort
563 Specifies whether to use a privileged port for outgoing connec‐
564 tions. The argument must be “yes” or “no”. The default is “no”.
565 If set to “yes”, ssh(1) must be setuid root. Note that this
566 option must be set to “yes” for RhostsRSAAuthentication with
567 older servers.
568 User Specifies the user to log in as. This can be useful when a dif‐
570 ferent user name is used on different machines. This saves the
571 trouble of having to remember to give the user name on the com‐
572 mand line.
573 UserKnownHostsFile
575 Specifies a file to use for the user host key database instead of
576 ~/.ssh/known_hosts.
577 VerifyHostKeyDNS
579 Specifies whether to verify the remote key using DNS and SSHFP
580 resource records. If this option is set to “yes”, the client
581 will implicitly trust keys that match a secure fingerprint from
582 DNS. Insecure fingerprints will be handled as if this option was
583 set to “ask”. If this option is set to “ask”, information on
584 fingerprint match will be displayed, but the user will still need
585 to confirm new host keys according to the StrictHostKeyChecking
586 option. The argument must be “yes”, “no”, or “ask”. The default
587 is “no”. Note that this option applies to protocol version 2
588 only.
589 See also VERIFYING HOST KEYS in ssh(1).
591 XAuthLocation
593 Specifies the full pathname of the xauth(1) program. The default
594 is /usr/bin/xauth.
595
597 A pattern consists of zero or more non-whitespace characters, ‘*’ (a
598 wildcard that matches zero or more characters), or ‘?’ (a wildcard that
599 matches exactly one character). For example, to specify a set of decla‐
600 rations for any host in the “.co.uk” set of domains, the following pat‐
601 tern could be used:
602 Host *.co.uk
604 The following pattern would match any host in the 192.168.0.[0-9] network
606 range:
607 Host 192.168.0.?
609 A pattern-list is a comma-separated list of patterns. Patterns within
611 pattern-lists may be negated by preceding them with an exclamation mark
612 (‘!’). For example, to allow a key to be used from anywhere within an
613 organisation except from the “dialup” pool, the following entry (in
614 authorized_keys) could be used:
615 from="!*.dialup.example.com,*.example.com"
617
619 ~/.ssh/config
620 This is the per-user configuration file. The format of this file
621 is described above. This file is used by the SSH client.
622 Because of the potential for abuse, this file must have strict
623 permissions: read/write for the user, and not accessible by oth‐
624 ers.
625 /etc/ssh/ssh_config
627 Systemwide configuration file. This file provides defaults for
628 those values that are not specified in the user's configuration
629 file, and for those users who do not have a configuration file.
630 This file must be world-readable.
631
633 ssh(1)
634
636 OpenSSH is a derivative of the original and free ssh 1.2.12 release by
637 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
638 de Raadt and Dug Song removed many bugs, re-added newer features and cre‐
639 ated OpenSSH. Markus Friedl contributed the support for SSH protocol
640 versions 1.5 and 2.0.
641BSD September 25, 1999 BSD