ssh_config.0 revision 180740
1SSH_CONFIG(5) OpenBSD Programmer's Manual SSH_CONFIG(5) 2 3NAME 4 ssh_config - OpenSSH SSH client configuration files 5 6SYNOPSIS 7 ~/.ssh/config 8 /etc/ssh/ssh_config 9 10DESCRIPTION 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 600PATTERNS 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 622FILES 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 635SEE ALSO 636 ssh(1) 637 638AUTHORS 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 645OpenBSD 4.1 September 25, 1999 10 646