Annotation of src/usr.bin/ssh/ssh_config.5, Revision 1.35
1.1 stevesk 1: .\" -*- nroff -*-
2: .\"
3: .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4: .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: .\" All rights reserved
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7: .\" As far as I am concerned, the code I have written for this software
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9: .\" software must be clearly marked as such, and if the derived work is
10: .\" incompatible with the protocol description in the RFC file, it must be
11: .\" called by a name other than "ssh" or "Secure Shell".
12: .\"
13: .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
14: .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
15: .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
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1.35 ! dtucker 37: .\" $OpenBSD: ssh_config.5,v 1.34 2004/05/06 11:24:23 jmc Exp $
1.1 stevesk 38: .Dd September 25, 1999
39: .Dt SSH_CONFIG 5
40: .Os
41: .Sh NAME
42: .Nm ssh_config
43: .Nd OpenSSH SSH client configuration files
44: .Sh SYNOPSIS
45: .Bl -tag -width Ds -compact
46: .It Pa $HOME/.ssh/config
47: .It Pa /etc/ssh/ssh_config
48: .El
49: .Sh DESCRIPTION
50: .Nm ssh
51: obtains configuration data from the following sources in
52: the following order:
1.2 stevesk 53: .Bl -enum -offset indent -compact
54: .It
55: command-line options
56: .It
57: user's configuration file
58: .Pq Pa $HOME/.ssh/config
59: .It
60: system-wide configuration file
61: .Pq Pa /etc/ssh/ssh_config
62: .El
1.1 stevesk 63: .Pp
64: For each parameter, the first obtained value
65: will be used.
66: The configuration files contain sections bracketed by
67: .Dq Host
68: specifications, and that section is only applied for hosts that
69: match one of the patterns given in the specification.
70: The matched host name is the one given on the command line.
71: .Pp
72: Since the first obtained value for each parameter is used, more
73: host-specific declarations should be given near the beginning of the
74: file, and general defaults at the end.
75: .Pp
76: The configuration file has the following format:
77: .Pp
78: Empty lines and lines starting with
79: .Ql #
80: are comments.
81: .Pp
82: Otherwise a line is of the format
83: .Dq keyword arguments .
84: Configuration options may be separated by whitespace or
85: optional whitespace and exactly one
86: .Ql = ;
87: the latter format is useful to avoid the need to quote whitespace
88: when specifying configuration options using the
89: .Nm ssh ,
90: .Nm scp
91: and
92: .Nm sftp
93: .Fl o
94: option.
95: .Pp
96: The possible
97: keywords and their meanings are as follows (note that
98: keywords are case-insensitive and arguments are case-sensitive):
99: .Bl -tag -width Ds
100: .It Cm Host
101: Restricts the following declarations (up to the next
102: .Cm Host
103: keyword) to be only for those hosts that match one of the patterns
104: given after the keyword.
105: .Ql \&*
106: and
1.20 jmc 107: .Ql \&?
1.1 stevesk 108: can be used as wildcards in the
109: patterns.
110: A single
111: .Ql \&*
112: as a pattern can be used to provide global
113: defaults for all hosts.
114: The host is the
115: .Ar hostname
116: argument given on the command line (i.e., the name is not converted to
117: a canonicalized host name before matching).
1.10 djm 118: .It Cm AddressFamily
1.11 jmc 119: Specifies which address family to use when connecting.
120: Valid arguments are
1.10 djm 121: .Dq any ,
122: .Dq inet
123: (Use IPv4 only) or
124: .Dq inet6
125: (Use IPv6 only.)
1.1 stevesk 126: .It Cm BatchMode
127: If set to
128: .Dq yes ,
129: passphrase/password querying will be disabled.
130: This option is useful in scripts and other batch jobs where no user
131: is present to supply the password.
132: The argument must be
133: .Dq yes
134: or
135: .Dq no .
136: The default is
137: .Dq no .
138: .It Cm BindAddress
139: Specify the interface to transmit from on machines with multiple
140: interfaces or aliased addresses.
141: Note that this option does not work if
142: .Cm UsePrivilegedPort
143: is set to
144: .Dq yes .
145: .It Cm ChallengeResponseAuthentication
146: Specifies whether to use challenge response authentication.
147: The argument to this keyword must be
148: .Dq yes
149: or
150: .Dq no .
151: The default is
152: .Dq yes .
153: .It Cm CheckHostIP
154: If this flag is set to
155: .Dq yes ,
156: ssh will additionally check the host IP address in the
157: .Pa known_hosts
158: file.
159: This allows ssh to detect if a host key changed due to DNS spoofing.
160: If the option is set to
161: .Dq no ,
162: the check will not be executed.
163: The default is
164: .Dq yes .
165: .It Cm Cipher
166: Specifies the cipher to use for encrypting the session
167: in protocol version 1.
168: Currently,
169: .Dq blowfish ,
170: .Dq 3des ,
171: and
172: .Dq des
173: are supported.
174: .Ar des
175: is only supported in the
176: .Nm ssh
177: client for interoperability with legacy protocol 1 implementations
178: that do not support the
179: .Ar 3des
1.7 jmc 180: cipher.
181: Its use is strongly discouraged due to cryptographic weaknesses.
1.1 stevesk 182: The default is
183: .Dq 3des .
184: .It Cm Ciphers
185: Specifies the ciphers allowed for protocol version 2
186: in order of preference.
187: Multiple ciphers must be comma-separated.
1.35 ! dtucker 188: The supported ciphers are
! 189: .Dq 3des-cbc ,
! 190: .Dq aes128-cbc ,
! 191: .Dq aes192-cbc ,
! 192: .Dq aes256-cbc ,
! 193: .Dq aes128-ctr ,
! 194: .Dq aes192-ctr ,
! 195: .Dq aes256-ctr ,
! 196: .Dq arcfour ,
! 197: .Dq blowfish-cbc ,
! 198: and
! 199: .Dq cast128-cbc .
1.1 stevesk 200: The default is
201: .Bd -literal
202: ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
203: aes192-cbc,aes256-cbc''
204: .Ed
205: .It Cm ClearAllForwardings
206: Specifies that all local, remote and dynamic port forwardings
207: specified in the configuration files or on the command line be
1.7 jmc 208: cleared.
209: This option is primarily useful when used from the
1.1 stevesk 210: .Nm ssh
211: command line to clear port forwardings set in
212: configuration files, and is automatically set by
213: .Xr scp 1
214: and
215: .Xr sftp 1 .
216: The argument must be
217: .Dq yes
218: or
219: .Dq no .
220: The default is
221: .Dq no .
222: .It Cm Compression
223: Specifies whether to use compression.
224: The argument must be
225: .Dq yes
226: or
227: .Dq no .
228: The default is
229: .Dq no .
230: .It Cm CompressionLevel
231: Specifies the compression level to use if compression is enabled.
232: The argument must be an integer from 1 (fast) to 9 (slow, best).
233: The default level is 6, which is good for most applications.
234: The meaning of the values is the same as in
235: .Xr gzip 1 .
236: Note that this option applies to protocol version 1 only.
237: .It Cm ConnectionAttempts
238: Specifies the number of tries (one per second) to make before exiting.
239: The argument must be an integer.
240: This may be useful in scripts if the connection sometimes fails.
241: The default is 1.
1.9 djm 242: .It Cm ConnectTimeout
243: Specifies the timeout (in seconds) used when connecting to the ssh
1.11 jmc 244: server, instead of using the default system TCP timeout.
245: This value is used only when the target is down or really unreachable,
246: not when it refuses the connection.
1.1 stevesk 247: .It Cm DynamicForward
248: Specifies that a TCP/IP port on the local machine be forwarded
249: over the secure channel, and the application
250: protocol is then used to determine where to connect to from the
1.7 jmc 251: remote machine.
252: The argument must be a port number.
1.15 markus 253: Currently the SOCKS4 and SOCKS5 protocols are supported, and
1.1 stevesk 254: .Nm ssh
1.15 markus 255: will act as a SOCKS server.
1.1 stevesk 256: Multiple forwardings may be specified, and
1.7 jmc 257: additional forwardings can be given on the command line.
258: Only the superuser can forward privileged ports.
1.14 markus 259: .It Cm EnableSSHKeysign
260: Setting this option to
261: .Dq yes
262: in the global client configuration file
263: .Pa /etc/ssh/ssh_config
264: enables the use of the helper program
265: .Xr ssh-keysign 8
266: during
267: .Cm HostbasedAuthentication .
268: The argument must be
269: .Dq yes
270: or
271: .Dq no .
272: The default is
273: .Dq no .
1.23 jmc 274: This option should be placed in the non-hostspecific section.
1.14 markus 275: See
276: .Xr ssh-keysign 8
277: for more information.
1.1 stevesk 278: .It Cm EscapeChar
279: Sets the escape character (default:
280: .Ql ~ ) .
281: The escape character can also
282: be set on the command line.
283: The argument should be a single character,
284: .Ql ^
285: followed by a letter, or
286: .Dq none
287: to disable the escape
288: character entirely (making the connection transparent for binary
289: data).
290: .It Cm ForwardAgent
291: Specifies whether the connection to the authentication agent (if any)
292: will be forwarded to the remote machine.
293: The argument must be
294: .Dq yes
295: or
296: .Dq no .
297: The default is
298: .Dq no .
1.3 stevesk 299: .Pp
1.7 jmc 300: Agent forwarding should be enabled with caution.
301: Users with the ability to bypass file permissions on the remote host
302: (for the agent's Unix-domain socket)
303: can access the local agent through the forwarded connection.
304: An attacker cannot obtain key material from the agent,
1.3 stevesk 305: however they can perform operations on the keys that enable them to
306: authenticate using the identities loaded into the agent.
1.1 stevesk 307: .It Cm ForwardX11
308: Specifies whether X11 connections will be automatically redirected
309: over the secure channel and
310: .Ev DISPLAY
311: set.
312: The argument must be
313: .Dq yes
314: or
315: .Dq no .
316: The default is
317: .Dq no .
1.3 stevesk 318: .Pp
1.7 jmc 319: X11 forwarding should be enabled with caution.
320: Users with the ability to bypass file permissions on the remote host
1.22 markus 321: (for the user's X11 authorization database)
1.7 jmc 322: can access the local X11 display through the forwarded connection.
1.22 markus 323: An attacker may then be able to perform activities such as keystroke monitoring
324: if the
325: .Cm ForwardX11Trusted
326: option is also enabled.
327: .It Cm ForwardX11Trusted
1.34 jmc 328: If this option is set to
1.22 markus 329: .Dq yes
330: then remote X11 clients will have full access to the original X11 display.
331: If this option is set to
332: .Dq no
333: then remote X11 clients will be considered untrusted and prevented
334: from stealing or tampering with data belonging to trusted X11
335: clients.
336: .Pp
337: The default is
338: .Dq no .
339: .Pp
340: See the X11 SECURITY extension specification for full details on
341: the restrictions imposed on untrusted clients.
1.1 stevesk 342: .It Cm GatewayPorts
343: Specifies whether remote hosts are allowed to connect to local
344: forwarded ports.
345: By default,
346: .Nm ssh
1.7 jmc 347: binds local port forwardings to the loopback address.
348: This prevents other remote hosts from connecting to forwarded ports.
1.1 stevesk 349: .Cm GatewayPorts
350: can be used to specify that
351: .Nm ssh
352: should bind local port forwardings to the wildcard address,
353: thus allowing remote hosts to connect to forwarded ports.
354: The argument must be
355: .Dq yes
356: or
357: .Dq no .
358: The default is
359: .Dq no .
360: .It Cm GlobalKnownHostsFile
361: Specifies a file to use for the global
362: host key database instead of
363: .Pa /etc/ssh/ssh_known_hosts .
1.18 markus 364: .It Cm GSSAPIAuthentication
1.27 markus 365: Specifies whether user authentication based on GSSAPI is allowed.
1.20 jmc 366: The default is
1.21 markus 367: .Dq no .
1.18 markus 368: Note that this option applies to protocol version 2 only.
369: .It Cm GSSAPIDelegateCredentials
370: Forward (delegate) credentials to the server.
371: The default is
372: .Dq no .
373: Note that this option applies to protocol version 2 only.
1.1 stevesk 374: .It Cm HostbasedAuthentication
375: Specifies whether to try rhosts based authentication with public key
376: authentication.
377: The argument must be
378: .Dq yes
379: or
380: .Dq no .
381: The default is
382: .Dq no .
383: This option applies to protocol version 2 only and
384: is similar to
385: .Cm RhostsRSAAuthentication .
386: .It Cm HostKeyAlgorithms
387: Specifies the protocol version 2 host key algorithms
388: that the client wants to use in order of preference.
389: The default for this option is:
390: .Dq ssh-rsa,ssh-dss .
391: .It Cm HostKeyAlias
392: Specifies an alias that should be used instead of the
393: real host name when looking up or saving the host key
394: in the host key database files.
395: This option is useful for tunneling ssh connections
396: or for multiple servers running on a single host.
397: .It Cm HostName
398: Specifies the real host name to log into.
399: This can be used to specify nicknames or abbreviations for hosts.
400: Default is the name given on the command line.
401: Numeric IP addresses are also permitted (both on the command line and in
402: .Cm HostName
403: specifications).
404: .It Cm IdentityFile
405: Specifies a file from which the user's RSA or DSA authentication identity
1.11 jmc 406: is read.
407: The default is
1.1 stevesk 408: .Pa $HOME/.ssh/identity
409: for protocol version 1, and
410: .Pa $HOME/.ssh/id_rsa
411: and
412: .Pa $HOME/.ssh/id_dsa
413: for protocol version 2.
414: Additionally, any identities represented by the authentication agent
415: will be used for authentication.
416: The file name may use the tilde
417: syntax to refer to a user's home directory.
418: It is possible to have
419: multiple identity files specified in configuration files; all these
420: identities will be tried in sequence.
1.29 markus 421: .It Cm IdentitiesOnly
422: Specifies that
423: .Nm ssh
424: should only use the authentication identity files configured in the
1.31 jmc 425: .Nm
1.29 markus 426: files,
427: even if the
428: .Nm ssh-agent
429: offers more identities.
430: The argument to this keyword must be
431: .Dq yes
432: or
433: .Dq no .
434: This option is intented for situations where
435: .Nm ssh-agent
436: offers many different identities.
437: The default is
438: .Dq no .
1.1 stevesk 439: .It Cm LocalForward
440: Specifies that a TCP/IP port on the local machine be forwarded over
441: the secure channel to the specified host and port from the remote machine.
442: The first argument must be a port number, and the second must be
443: .Ar host:port .
444: IPv6 addresses can be specified with an alternative syntax:
445: .Ar host/port .
446: Multiple forwardings may be specified, and additional
447: forwardings can be given on the command line.
448: Only the superuser can forward privileged ports.
449: .It Cm LogLevel
450: Gives the verbosity level that is used when logging messages from
451: .Nm ssh .
452: The possible values are:
453: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3.
1.7 jmc 454: The default is INFO.
455: DEBUG and DEBUG1 are equivalent.
456: DEBUG2 and DEBUG3 each specify higher levels of verbose output.
1.1 stevesk 457: .It Cm MACs
458: Specifies the MAC (message authentication code) algorithms
459: in order of preference.
460: The MAC algorithm is used in protocol version 2
461: for data integrity protection.
462: Multiple algorithms must be comma-separated.
463: The default is
464: .Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
465: .It Cm NoHostAuthenticationForLocalhost
466: This option can be used if the home directory is shared across machines.
467: In this case localhost will refer to a different machine on each of
468: the machines and the user will get many warnings about changed host keys.
469: However, this option disables host authentication for localhost.
470: The argument to this keyword must be
471: .Dq yes
472: or
473: .Dq no .
474: The default is to check the host key for localhost.
475: .It Cm NumberOfPasswordPrompts
476: Specifies the number of password prompts before giving up.
477: The argument to this keyword must be an integer.
478: Default is 3.
479: .It Cm PasswordAuthentication
480: Specifies whether to use password authentication.
481: The argument to this keyword must be
482: .Dq yes
483: or
484: .Dq no .
485: The default is
486: .Dq yes .
487: .It Cm Port
488: Specifies the port number to connect on the remote host.
489: Default is 22.
490: .It Cm PreferredAuthentications
491: Specifies the order in which the client should try protocol 2
1.11 jmc 492: authentication methods.
493: This allows a client to prefer one method (e.g.
1.1 stevesk 494: .Cm keyboard-interactive )
495: over another method (e.g.
496: .Cm password )
497: The default for this option is:
498: .Dq hostbased,publickey,keyboard-interactive,password .
499: .It Cm Protocol
500: Specifies the protocol versions
501: .Nm ssh
502: should support in order of preference.
503: The possible values are
504: .Dq 1
505: and
506: .Dq 2 .
507: Multiple versions must be comma-separated.
508: The default is
509: .Dq 2,1 .
510: This means that
511: .Nm ssh
512: tries version 2 and falls back to version 1
513: if version 2 is not available.
514: .It Cm ProxyCommand
515: Specifies the command to use to connect to the server.
516: The command
517: string extends to the end of the line, and is executed with
518: .Pa /bin/sh .
519: In the command string,
520: .Ql %h
521: will be substituted by the host name to
522: connect and
523: .Ql %p
524: by the port.
525: The command can be basically anything,
526: and should read from its standard input and write to its standard output.
527: It should eventually connect an
528: .Xr sshd 8
529: server running on some machine, or execute
530: .Ic sshd -i
531: somewhere.
532: Host key management will be done using the
533: HostName of the host being connected (defaulting to the name typed by
534: the user).
1.7 jmc 535: Setting the command to
536: .Dq none
1.6 markus 537: disables this option entirely.
1.1 stevesk 538: Note that
539: .Cm CheckHostIP
540: is not available for connects with a proxy command.
541: .Pp
542: .It Cm PubkeyAuthentication
543: Specifies whether to try public key authentication.
544: The argument to this keyword must be
545: .Dq yes
546: or
547: .Dq no .
548: The default is
549: .Dq yes .
550: This option applies to protocol version 2 only.
551: .It Cm RemoteForward
552: Specifies that a TCP/IP port on the remote machine be forwarded over
553: the secure channel to the specified host and port from the local machine.
554: The first argument must be a port number, and the second must be
555: .Ar host:port .
556: IPv6 addresses can be specified with an alternative syntax:
557: .Ar host/port .
558: Multiple forwardings may be specified, and additional
559: forwardings can be given on the command line.
560: Only the superuser can forward privileged ports.
561: .It Cm RhostsRSAAuthentication
562: Specifies whether to try rhosts based authentication with RSA host
563: authentication.
564: The argument must be
565: .Dq yes
566: or
567: .Dq no .
568: The default is
569: .Dq no .
570: This option applies to protocol version 1 only and requires
571: .Nm ssh
572: to be setuid root.
573: .It Cm RSAAuthentication
574: Specifies whether to try RSA authentication.
575: The argument to this keyword must be
576: .Dq yes
577: or
578: .Dq no .
579: RSA authentication will only be
580: attempted if the identity file exists, or an authentication agent is
581: running.
582: The default is
583: .Dq yes .
584: Note that this option applies to protocol version 1 only.
1.32 djm 585: .It Cm SendEnv
586: Specifies what variables from the local
587: .Xr environ 7
588: should be sent to the server.
589: Note that environment passing is only supported for protocol 2, the
1.33 djm 590: server must also support it, and the server must be configured to
591: accept these environment variables.
1.32 djm 592: Refer to
593: .Cm AcceptEnv
594: in
595: .Xr sshd_config 5
596: for how to configure the server.
597: Variables are specified by name, which may contain the wildcard characters
598: .Ql \&*
599: and
600: .Ql \&? .
1.33 djm 601: Multiple environment variables may be separated by whitespace or spread
1.32 djm 602: across multiple
603: .Cm SendEnv
604: directives.
605: The default is not to send any environment variables.
1.28 markus 606: .It Cm ServerAliveInterval
607: Sets a timeout interval in seconds after which if no data has been received
608: from the server,
609: .Nm ssh
610: will send a message through the encrypted
611: channel to request a response from the server.
612: The default
613: is 0, indicating that these messages will not be sent to the server.
614: This option applies to protocol version 2 only.
615: .It Cm ServerAliveCountMax
616: Sets the number of server alive messages (see above) which may be
617: sent without
618: .Nm ssh
619: receiving any messages back from the server.
620: If this threshold is reached while server alive messages are being sent,
621: .Nm ssh
622: will disconnect from the server, terminating the session.
623: It is important to note that the use of server alive messages is very
624: different from
625: .Cm TCPKeepAlive
626: (below).
627: The server alive messages are sent through the encrypted channel
628: and therefore will not be spoofable.
629: The TCP keepalive option enabled by
630: .Cm TCPKeepAlive
631: is spoofable.
632: The server alive mechanism is valuable when the client or
633: server depend on knowing when a connection has become inactive.
634: .Pp
635: The default value is 3.
636: If, for example,
637: .Cm ServerAliveInterval
638: (above) is set to 15, and
639: .Cm ServerAliveCountMax
640: is left at the default, if the server becomes unresponsive ssh
641: will disconnect after approximately 45 seconds.
1.1 stevesk 642: .It Cm SmartcardDevice
1.11 jmc 643: Specifies which smartcard device to use.
644: The argument to this keyword is the device
1.1 stevesk 645: .Nm ssh
646: should use to communicate with a smartcard used for storing the user's
1.11 jmc 647: private RSA key.
648: By default, no device is specified and smartcard support is not activated.
1.1 stevesk 649: .It Cm StrictHostKeyChecking
650: If this flag is set to
651: .Dq yes ,
652: .Nm ssh
653: will never automatically add host keys to the
654: .Pa $HOME/.ssh/known_hosts
655: file, and refuses to connect to hosts whose host key has changed.
656: This provides maximum protection against trojan horse attacks,
657: however, can be annoying when the
658: .Pa /etc/ssh/ssh_known_hosts
659: file is poorly maintained, or connections to new hosts are
660: frequently made.
661: This option forces the user to manually
662: add all new hosts.
663: If this flag is set to
664: .Dq no ,
665: .Nm ssh
666: will automatically add new host keys to the
667: user known hosts files.
668: If this flag is set to
669: .Dq ask ,
670: new host keys
671: will be added to the user known host files only after the user
672: has confirmed that is what they really want to do, and
673: .Nm ssh
674: will refuse to connect to hosts whose host key has changed.
675: The host keys of
676: known hosts will be verified automatically in all cases.
677: The argument must be
678: .Dq yes ,
679: .Dq no
680: or
681: .Dq ask .
682: The default is
683: .Dq ask .
1.26 markus 684: .It Cm TCPKeepAlive
685: Specifies whether the system should send TCP keepalive messages to the
686: other side.
687: If they are sent, death of the connection or crash of one
688: of the machines will be properly noticed.
689: However, this means that
690: connections will die if the route is down temporarily, and some people
691: find it annoying.
692: .Pp
693: The default is
694: .Dq yes
695: (to send TCP keepalive messages), and the client will notice
696: if the network goes down or the remote host dies.
697: This is important in scripts, and many users want it too.
698: .Pp
699: To disable TCP keepalive messages, the value should be set to
700: .Dq no .
1.1 stevesk 701: .It Cm UsePrivilegedPort
702: Specifies whether to use a privileged port for outgoing connections.
703: The argument must be
704: .Dq yes
705: or
706: .Dq no .
707: The default is
708: .Dq no .
1.4 stevesk 709: If set to
710: .Dq yes
711: .Nm ssh
712: must be setuid root.
1.1 stevesk 713: Note that this option must be set to
714: .Dq yes
1.17 markus 715: for
1.1 stevesk 716: .Cm RhostsRSAAuthentication
1.17 markus 717: with older servers.
1.1 stevesk 718: .It Cm User
719: Specifies the user to log in as.
720: This can be useful when a different user name is used on different machines.
721: This saves the trouble of
722: having to remember to give the user name on the command line.
723: .It Cm UserKnownHostsFile
724: Specifies a file to use for the user
725: host key database instead of
726: .Pa $HOME/.ssh/known_hosts .
1.8 jakob 727: .It Cm VerifyHostKeyDNS
728: Specifies whether to verify the remote key using DNS and SSHFP resource
729: records.
1.24 jakob 730: If this option is set to
731: .Dq yes ,
1.25 jmc 732: the client will implicitly trust keys that match a secure fingerprint
1.24 jakob 733: from DNS.
734: Insecure fingerprints will be handled as if this option was set to
735: .Dq ask .
736: If this option is set to
737: .Dq ask ,
738: information on fingerprint match will be displayed, but the user will still
739: need to confirm new host keys according to the
740: .Cm StrictHostKeyChecking
741: option.
742: The argument must be
743: .Dq yes ,
744: .Dq no
1.25 jmc 745: or
746: .Dq ask .
1.8 jakob 747: The default is
748: .Dq no .
1.12 jakob 749: Note that this option applies to protocol version 2 only.
1.1 stevesk 750: .It Cm XAuthLocation
1.5 stevesk 751: Specifies the full pathname of the
1.1 stevesk 752: .Xr xauth 1
753: program.
754: The default is
755: .Pa /usr/X11R6/bin/xauth .
756: .El
757: .Sh FILES
758: .Bl -tag -width Ds
759: .It Pa $HOME/.ssh/config
760: This is the per-user configuration file.
761: The format of this file is described above.
762: This file is used by the
763: .Nm ssh
764: client.
1.30 djm 765: Because of the potential for abuse, this file must have strict permissions:
766: read/write for the user, and not accessible by others.
1.1 stevesk 767: .It Pa /etc/ssh/ssh_config
768: Systemwide configuration file.
769: This file provides defaults for those
770: values that are not specified in the user's configuration file, and
771: for those users who do not have a configuration file.
772: This file must be world-readable.
773: .El
1.13 jmc 774: .Sh SEE ALSO
775: .Xr ssh 1
1.1 stevesk 776: .Sh AUTHORS
777: OpenSSH is a derivative of the original and free
778: ssh 1.2.12 release by Tatu Ylonen.
779: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
780: Theo de Raadt and Dug Song
781: removed many bugs, re-added newer features and
782: created OpenSSH.
783: Markus Friedl contributed the support for SSH
784: protocol versions 1.5 and 2.0.
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