ssh_config.0 revision 207311
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. 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. ssh(1) will try 320 to load certificate information from the filename obtained by ap- 321 pending -cert.pub to the path of a specified IdentityFile. 322 323 The file name may use the tilde syntax to refer to a user's home 324 directory or one of the following escape characters: `%d' (local 325 user's home directory), `%u' (local user name), `%l' (local host 326 name), `%h' (remote host name) or `%r' (remote user name). 327 328 It is possible to have multiple identity files specified in con- 329 figuration files; all these identities will be tried in sequence. 330 331 KbdInteractiveAuthentication 332 Specifies whether to use keyboard-interactive authentication. 333 The argument to this keyword must be ``yes'' or ``no''. The de- 334 fault is ``yes''. 335 336 KbdInteractiveDevices 337 Specifies the list of methods to use in keyboard-interactive au- 338 thentication. Multiple method names must be comma-separated. 339 The default is to use the server specified list. The methods 340 available vary depending on what the server supports. For an 341 OpenSSH server, it may be zero or more of: ``bsdauth'', ``pam'', 342 and ``skey''. 343 344 LocalCommand 345 Specifies a command to execute on the local machine after suc- 346 cessfully connecting to the server. The command string extends 347 to the end of the line, and is executed with the user's shell. 348 The following escape character substitutions will be performed: 349 `%d' (local user's home directory), `%h' (remote host name), `%l' 350 (local host name), `%n' (host name as provided on the command 351 line), `%p' (remote port), `%r' (remote user name) or `%u' (local 352 user name). 353 354 The command is run synchronously and does not have access to the 355 session of the ssh(1) that spawned it. It should not be used for 356 interactive commands. 357 358 This directive is ignored unless PermitLocalCommand has been en- 359 abled. 360 361 LocalForward 362 Specifies that a TCP port on the local machine be forwarded over 363 the secure channel to the specified host and port from the remote 364 machine. The first argument must be [bind_address:]port and the 365 second argument must be host:hostport. IPv6 addresses can be 366 specified by enclosing addresses in square brackets or by using 367 an alternative syntax: [bind_address/]port and host/hostport. 368 Multiple forwardings may be specified, and additional forwardings 369 can be given on the command line. Only the superuser can forward 370 privileged ports. By default, the local port is bound in accor- 371 dance with the GatewayPorts setting. However, an explicit 372 bind_address may be used to bind the connection to a specific ad- 373 dress. The bind_address of ``localhost'' indicates that the lis- 374 tening port be bound for local use only, while an empty address 375 or `*' indicates that the port should be available from all in- 376 terfaces. 377 378 LogLevel 379 Gives the verbosity level that is used when logging messages from 380 ssh(1). The possible values are: QUIET, FATAL, ERROR, INFO, VER- 381 BOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. 382 DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify 383 higher levels of verbose output. 384 385 MACs Specifies the MAC (message authentication code) algorithms in or- 386 der of preference. The MAC algorithm is used in protocol version 387 2 for data integrity protection. Multiple algorithms must be 388 comma-separated. The default is: 389 390 hmac-md5,hmac-sha1,umac-64@openssh.com, 391 hmac-ripemd160,hmac-sha1-96,hmac-md5-96 392 393 NoHostAuthenticationForLocalhost 394 This option can be used if the home directory is shared across 395 machines. In this case localhost will refer to a different ma- 396 chine on each of the machines and the user will get many warnings 397 about changed host keys. However, this option disables host au- 398 thentication for localhost. The argument to this keyword must be 399 ``yes'' or ``no''. The default is to check the host key for lo- 400 calhost. 401 402 NumberOfPasswordPrompts 403 Specifies the number of password prompts before giving up. The 404 argument to this keyword must be an integer. The default is 3. 405 406 PasswordAuthentication 407 Specifies whether to use password authentication. The argument 408 to this keyword must be ``yes'' or ``no''. The default is 409 ``yes''. 410 411 PermitLocalCommand 412 Allow local command execution via the LocalCommand option or us- 413 ing the !command escape sequence in ssh(1). The argument must be 414 ``yes'' or ``no''. The default is ``no''. 415 416 PKCS11Provider 417 Specifies which PKCS#11 provider to use. The argument to this 418 keyword is the PKCS#11 shared libary ssh(1) should use to commu- 419 nicate with a PKCS#11 token providing the user's private RSA key. 420 421 Port Specifies the port number to connect on the remote host. The de- 422 fault is 22. 423 424 PreferredAuthentications 425 Specifies the order in which the client should try protocol 2 au- 426 thentication methods. This allows a client to prefer one method 427 (e.g. keyboard-interactive) over another method (e.g. password) 428 The default for this option is: ``gssapi-with- 429 mic,hostbased,publickey,keyboard-interactive,password''. 430 431 Protocol 432 Specifies the protocol versions ssh(1) should support in order of 433 preference. The possible values are `1' and `2'. Multiple ver- 434 sions must be comma-separated. When this option is set to 435 ``2,1'' ssh will try version 2 and fall back to version 1 if ver- 436 sion 2 is not available. The default is `2'. 437 438 ProxyCommand 439 Specifies the command to use to connect to the server. The com- 440 mand string extends to the end of the line, and is executed with 441 the user's shell. In the command string, `%h' will be substitut- 442 ed by the host name to connect and `%p' by the port. The command 443 can be basically anything, and should read from its standard in- 444 put and write to its standard output. It should eventually con- 445 nect an sshd(8) server running on some machine, or execute sshd 446 -i somewhere. Host key management will be done using the Host- 447 Name of the host being connected (defaulting to the name typed by 448 the user). Setting the command to ``none'' disables this option 449 entirely. Note that CheckHostIP is not available for connects 450 with a proxy command. 451 452 This directive is useful in conjunction with nc(1) and its proxy 453 support. For example, the following directive would connect via 454 an HTTP proxy at 192.0.2.0: 455 456 ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p 457 458 PubkeyAuthentication 459 Specifies whether to try public key authentication. The argument 460 to this keyword must be ``yes'' or ``no''. The default is 461 ``yes''. This option applies to protocol version 2 only. 462 463 RekeyLimit 464 Specifies the maximum amount of data that may be transmitted be- 465 fore the session key is renegotiated. The argument is the number 466 of bytes, with an optional suffix of `K', `M', or `G' to indicate 467 Kilobytes, Megabytes, or Gigabytes, respectively. The default is 468 between `1G' and `4G', depending on the cipher. This option ap- 469 plies to protocol version 2 only. 470 471 RemoteForward 472 Specifies that a TCP port on the remote machine be forwarded over 473 the secure channel to the specified host and port from the local 474 machine. The first argument must be [bind_address:]port and the 475 second argument must be host:hostport. IPv6 addresses can be 476 specified by enclosing addresses in square brackets or by using 477 an alternative syntax: [bind_address/]port and host/hostport. 478 Multiple forwardings may be specified, and additional forwardings 479 can be given on the command line. Privileged ports can be for- 480 warded only when logging in as root on the remote machine. 481 482 If the port argument is `0', the listen port will be dynamically 483 allocated on the server and reported to the client at run time. 484 485 If the bind_address is not specified, the default is to only bind 486 to loopback addresses. If the bind_address is `*' or an empty 487 string, then the forwarding is requested to listen on all inter- 488 faces. Specifying a remote bind_address will only succeed if the 489 server's GatewayPorts option is enabled (see sshd_config(5)). 490 491 RhostsRSAAuthentication 492 Specifies whether to try rhosts based authentication with RSA 493 host authentication. The argument must be ``yes'' or ``no''. 494 The default is ``no''. This option applies to protocol version 1 495 only and requires ssh(1) to be setuid root. 496 497 RSAAuthentication 498 Specifies whether to try RSA authentication. The argument to 499 this keyword must be ``yes'' or ``no''. RSA authentication will 500 only be attempted if the identity file exists, or an authentica- 501 tion agent is running. The default is ``yes''. Note that this 502 option applies to protocol version 1 only. 503 504 SendEnv 505 Specifies what variables from the local environ(7) should be sent 506 to the server. Note that environment passing is only supported 507 for protocol 2. The server must also support it, and the server 508 must be configured to accept these environment variables. Refer 509 to AcceptEnv in sshd_config(5) for how to configure the server. 510 Variables are specified by name, which may contain wildcard char- 511 acters. Multiple environment variables may be separated by 512 whitespace or spread across multiple SendEnv directives. The de- 513 fault is not to send any environment variables. 514 515 See PATTERNS for more information on patterns. 516 517 ServerAliveCountMax 518 Sets the number of server alive messages (see below) which may be 519 sent without ssh(1) receiving any messages back from the server. 520 If this threshold is reached while server alive messages are be- 521 ing sent, ssh will disconnect from the server, terminating the 522 session. It is important to note that the use of server alive 523 messages is very different from TCPKeepAlive (below). The server 524 alive messages are sent through the encrypted channel and there- 525 fore will not be spoofable. The TCP keepalive option enabled by 526 TCPKeepAlive is spoofable. The server alive mechanism is valu- 527 able when the client or server depend on knowing when a connec- 528 tion has become inactive. 529 530 The default value is 3. If, for example, ServerAliveInterval 531 (see below) is set to 15 and ServerAliveCountMax is left at the 532 default, if the server becomes unresponsive, ssh will disconnect 533 after approximately 45 seconds. This option applies to protocol 534 version 2 only. 535 536 ServerAliveInterval 537 Sets a timeout interval in seconds after which if no data has 538 been received from the server, ssh(1) will send a message through 539 the encrypted channel to request a response from the server. The 540 default is 0, indicating that these messages will not be sent to 541 the server. This option applies to protocol version 2 only. 542 543 StrictHostKeyChecking 544 If this flag is set to ``yes'', ssh(1) will never automatically 545 add host keys to the ~/.ssh/known_hosts file, and refuses to con- 546 nect to hosts whose host key has changed. This provides maximum 547 protection against trojan horse attacks, though it can be annoy- 548 ing when the /etc/ssh/ssh_known_hosts file is poorly maintained 549 or when connections to new hosts are frequently made. This op- 550 tion forces the user to manually add all new hosts. If this flag 551 is set to ``no'', ssh will automatically add new host keys to the 552 user known hosts files. If this flag is set to ``ask'', new host 553 keys will be added to the user known host files only after the 554 user has confirmed that is what they really want to do, and ssh 555 will refuse to connect to hosts whose host key has changed. The 556 host keys of known hosts will be verified automatically in all 557 cases. The argument must be ``yes'', ``no'', or ``ask''. The 558 default is ``ask''. 559 560 TCPKeepAlive 561 Specifies whether the system should send TCP keepalive messages 562 to the other side. If they are sent, death of the connection or 563 crash of one of the machines will be properly noticed. However, 564 this means that connections will die if the route is down tem- 565 porarily, and some people find it annoying. 566 567 The default is ``yes'' (to send TCP keepalive messages), and the 568 client will notice if the network goes down or the remote host 569 dies. This is important in scripts, and many users want it too. 570 571 To disable TCP keepalive messages, the value should be set to 572 ``no''. 573 574 Tunnel Request tun(4) device forwarding between the client and the serv- 575 er. The argument must be ``yes'', ``point-to-point'' (layer 3), 576 ``ethernet'' (layer 2), or ``no''. Specifying ``yes'' requests 577 the default tunnel mode, which is ``point-to-point''. The de- 578 fault is ``no''. 579 580 TunnelDevice 581 Specifies the tun(4) devices to open on the client (local_tun) 582 and the server (remote_tun). 583 584 The argument must be local_tun[:remote_tun]. The devices may be 585 specified by numerical ID or the keyword ``any'', which uses the 586 next available tunnel device. If remote_tun is not specified, it 587 defaults to ``any''. The default is ``any:any''. 588 589 UsePrivilegedPort 590 Specifies whether to use a privileged port for outgoing connec- 591 tions. The argument must be ``yes'' or ``no''. The default is 592 ``no''. If set to ``yes'', ssh(1) must be setuid root. Note 593 that this option must be set to ``yes'' for 594 RhostsRSAAuthentication with older servers. 595 596 User Specifies the user to log in as. This can be useful when a dif- 597 ferent user name is used on different machines. This saves the 598 trouble of having to remember to give the user name on the com- 599 mand line. 600 601 UserKnownHostsFile 602 Specifies a file to use for the user host key database instead of 603 ~/.ssh/known_hosts. 604 605 VerifyHostKeyDNS 606 Specifies whether to verify the remote key using DNS and SSHFP 607 resource records. If this option is set to ``yes'', the client 608 will implicitly trust keys that match a secure fingerprint from 609 DNS. Insecure fingerprints will be handled as if this option was 610 set to ``ask''. If this option is set to ``ask'', information on 611 fingerprint match will be displayed, but the user will still need 612 to confirm new host keys according to the StrictHostKeyChecking 613 option. The argument must be ``yes'', ``no'', or ``ask''. The 614 default is ``no''. Note that this option applies to protocol 615 version 2 only. 616 617 See also VERIFYING HOST KEYS in ssh(1). 618 619 VisualHostKey 620 If this flag is set to ``yes'', an ASCII art representation of 621 the remote host key fingerprint is printed in addition to the hex 622 fingerprint string at login and for unknown host keys. If this 623 flag is set to ``no'', no fingerprint strings are printed at lo- 624 gin and only the hex fingerprint string will be printed for un- 625 known host keys. The default is ``no''. 626 627 XAuthLocation 628 Specifies the full pathname of the xauth(1) program. The default 629 is /usr/X11R6/bin/xauth. 630 631PATTERNS 632 A pattern consists of zero or more non-whitespace characters, `*' (a 633 wildcard that matches zero or more characters), or `?' (a wildcard that 634 matches exactly one character). For example, to specify a set of decla- 635 rations for any host in the ``.co.uk'' set of domains, the following pat- 636 tern could be used: 637 638 Host *.co.uk 639 640 The following pattern would match any host in the 192.168.0.[0-9] network 641 range: 642 643 Host 192.168.0.? 644 645 A pattern-list is a comma-separated list of patterns. Patterns within 646 pattern-lists may be negated by preceding them with an exclamation mark 647 (`!'). For example, to allow a key to be used from anywhere within an 648 organisation except from the ``dialup'' pool, the following entry (in au- 649 thorized_keys) could be used: 650 651 from="!*.dialup.example.com,*.example.com" 652 653FILES 654 ~/.ssh/config 655 This is the per-user configuration file. The format of this file 656 is described above. This file is used by the SSH client. Be- 657 cause of the potential for abuse, this file must have strict per- 658 missions: read/write for the user, and not accessible by others. 659 660 /etc/ssh/ssh_config 661 Systemwide configuration file. This file provides defaults for 662 those values that are not specified in the user's configuration 663 file, and for those users who do not have a configuration file. 664 This file must be world-readable. 665 666SEE ALSO 667 ssh(1) 668 669AUTHORS 670 OpenSSH is a derivative of the original and free ssh 1.2.12 release by 671 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo 672 de Raadt and Dug Song removed many bugs, re-added newer features and cre- 673 ated OpenSSH. Markus Friedl contributed the support for SSH protocol 674 versions 1.5 and 2.0. 675 676OpenBSD 4.7 March 26, 2010 11 677