Annotation of src/usr.bin/ssh/ssh_config.5, Revision 1.34
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
6: .\"
7: .\" As far as I am concerned, the code I have written for this software
8: .\" can be used freely for any purpose. Any derived versions of this
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.
16: .\"
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22: .\" 2. Redistributions in binary form must reproduce the above copyright
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1.34 ! jmc 37: .\" $OpenBSD: ssh_config.5,v 1.33 2004/04/28 05:17:10 djm 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.
188: The default is
189: .Bd -literal
190: ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
191: aes192-cbc,aes256-cbc''
192: .Ed
193: .It Cm ClearAllForwardings
194: Specifies that all local, remote and dynamic port forwardings
195: specified in the configuration files or on the command line be
1.7 jmc 196: cleared.
197: This option is primarily useful when used from the
1.1 stevesk 198: .Nm ssh
199: command line to clear port forwardings set in
200: configuration files, and is automatically set by
201: .Xr scp 1
202: and
203: .Xr sftp 1 .
204: The argument must be
205: .Dq yes
206: or
207: .Dq no .
208: The default is
209: .Dq no .
210: .It Cm Compression
211: Specifies whether to use compression.
212: The argument must be
213: .Dq yes
214: or
215: .Dq no .
216: The default is
217: .Dq no .
218: .It Cm CompressionLevel
219: Specifies the compression level to use if compression is enabled.
220: The argument must be an integer from 1 (fast) to 9 (slow, best).
221: The default level is 6, which is good for most applications.
222: The meaning of the values is the same as in
223: .Xr gzip 1 .
224: Note that this option applies to protocol version 1 only.
225: .It Cm ConnectionAttempts
226: Specifies the number of tries (one per second) to make before exiting.
227: The argument must be an integer.
228: This may be useful in scripts if the connection sometimes fails.
229: The default is 1.
1.9 djm 230: .It Cm ConnectTimeout
231: Specifies the timeout (in seconds) used when connecting to the ssh
1.11 jmc 232: server, instead of using the default system TCP timeout.
233: This value is used only when the target is down or really unreachable,
234: not when it refuses the connection.
1.1 stevesk 235: .It Cm DynamicForward
236: Specifies that a TCP/IP port on the local machine be forwarded
237: over the secure channel, and the application
238: protocol is then used to determine where to connect to from the
1.7 jmc 239: remote machine.
240: The argument must be a port number.
1.15 markus 241: Currently the SOCKS4 and SOCKS5 protocols are supported, and
1.1 stevesk 242: .Nm ssh
1.15 markus 243: will act as a SOCKS server.
1.1 stevesk 244: Multiple forwardings may be specified, and
1.7 jmc 245: additional forwardings can be given on the command line.
246: Only the superuser can forward privileged ports.
1.14 markus 247: .It Cm EnableSSHKeysign
248: Setting this option to
249: .Dq yes
250: in the global client configuration file
251: .Pa /etc/ssh/ssh_config
252: enables the use of the helper program
253: .Xr ssh-keysign 8
254: during
255: .Cm HostbasedAuthentication .
256: The argument must be
257: .Dq yes
258: or
259: .Dq no .
260: The default is
261: .Dq no .
1.23 jmc 262: This option should be placed in the non-hostspecific section.
1.14 markus 263: See
264: .Xr ssh-keysign 8
265: for more information.
1.1 stevesk 266: .It Cm EscapeChar
267: Sets the escape character (default:
268: .Ql ~ ) .
269: The escape character can also
270: be set on the command line.
271: The argument should be a single character,
272: .Ql ^
273: followed by a letter, or
274: .Dq none
275: to disable the escape
276: character entirely (making the connection transparent for binary
277: data).
278: .It Cm ForwardAgent
279: Specifies whether the connection to the authentication agent (if any)
280: will be forwarded to the remote machine.
281: The argument must be
282: .Dq yes
283: or
284: .Dq no .
285: The default is
286: .Dq no .
1.3 stevesk 287: .Pp
1.7 jmc 288: Agent forwarding should be enabled with caution.
289: Users with the ability to bypass file permissions on the remote host
290: (for the agent's Unix-domain socket)
291: can access the local agent through the forwarded connection.
292: An attacker cannot obtain key material from the agent,
1.3 stevesk 293: however they can perform operations on the keys that enable them to
294: authenticate using the identities loaded into the agent.
1.1 stevesk 295: .It Cm ForwardX11
296: Specifies whether X11 connections will be automatically redirected
297: over the secure channel and
298: .Ev DISPLAY
299: set.
300: The argument must be
301: .Dq yes
302: or
303: .Dq no .
304: The default is
305: .Dq no .
1.3 stevesk 306: .Pp
1.7 jmc 307: X11 forwarding should be enabled with caution.
308: Users with the ability to bypass file permissions on the remote host
1.22 markus 309: (for the user's X11 authorization database)
1.7 jmc 310: can access the local X11 display through the forwarded connection.
1.22 markus 311: An attacker may then be able to perform activities such as keystroke monitoring
312: if the
313: .Cm ForwardX11Trusted
314: option is also enabled.
315: .It Cm ForwardX11Trusted
1.34 ! jmc 316: If this option is set to
1.22 markus 317: .Dq yes
318: then remote X11 clients will have full access to the original X11 display.
319: If this option is set to
320: .Dq no
321: then remote X11 clients will be considered untrusted and prevented
322: from stealing or tampering with data belonging to trusted X11
323: clients.
324: .Pp
325: The default is
326: .Dq no .
327: .Pp
328: See the X11 SECURITY extension specification for full details on
329: the restrictions imposed on untrusted clients.
1.1 stevesk 330: .It Cm GatewayPorts
331: Specifies whether remote hosts are allowed to connect to local
332: forwarded ports.
333: By default,
334: .Nm ssh
1.7 jmc 335: binds local port forwardings to the loopback address.
336: This prevents other remote hosts from connecting to forwarded ports.
1.1 stevesk 337: .Cm GatewayPorts
338: can be used to specify that
339: .Nm ssh
340: should bind local port forwardings to the wildcard address,
341: thus allowing remote hosts to connect to forwarded ports.
342: The argument must be
343: .Dq yes
344: or
345: .Dq no .
346: The default is
347: .Dq no .
348: .It Cm GlobalKnownHostsFile
349: Specifies a file to use for the global
350: host key database instead of
351: .Pa /etc/ssh/ssh_known_hosts .
1.18 markus 352: .It Cm GSSAPIAuthentication
1.27 markus 353: Specifies whether user authentication based on GSSAPI is allowed.
1.20 jmc 354: The default is
1.21 markus 355: .Dq no .
1.18 markus 356: Note that this option applies to protocol version 2 only.
357: .It Cm GSSAPIDelegateCredentials
358: Forward (delegate) credentials to the server.
359: The default is
360: .Dq no .
361: Note that this option applies to protocol version 2 only.
1.1 stevesk 362: .It Cm HostbasedAuthentication
363: Specifies whether to try rhosts based authentication with public key
364: authentication.
365: The argument must be
366: .Dq yes
367: or
368: .Dq no .
369: The default is
370: .Dq no .
371: This option applies to protocol version 2 only and
372: is similar to
373: .Cm RhostsRSAAuthentication .
374: .It Cm HostKeyAlgorithms
375: Specifies the protocol version 2 host key algorithms
376: that the client wants to use in order of preference.
377: The default for this option is:
378: .Dq ssh-rsa,ssh-dss .
379: .It Cm HostKeyAlias
380: Specifies an alias that should be used instead of the
381: real host name when looking up or saving the host key
382: in the host key database files.
383: This option is useful for tunneling ssh connections
384: or for multiple servers running on a single host.
385: .It Cm HostName
386: Specifies the real host name to log into.
387: This can be used to specify nicknames or abbreviations for hosts.
388: Default is the name given on the command line.
389: Numeric IP addresses are also permitted (both on the command line and in
390: .Cm HostName
391: specifications).
392: .It Cm IdentityFile
393: Specifies a file from which the user's RSA or DSA authentication identity
1.11 jmc 394: is read.
395: The default is
1.1 stevesk 396: .Pa $HOME/.ssh/identity
397: for protocol version 1, and
398: .Pa $HOME/.ssh/id_rsa
399: and
400: .Pa $HOME/.ssh/id_dsa
401: for protocol version 2.
402: Additionally, any identities represented by the authentication agent
403: will be used for authentication.
404: The file name may use the tilde
405: syntax to refer to a user's home directory.
406: It is possible to have
407: multiple identity files specified in configuration files; all these
408: identities will be tried in sequence.
1.29 markus 409: .It Cm IdentitiesOnly
410: Specifies that
411: .Nm ssh
412: should only use the authentication identity files configured in the
1.31 jmc 413: .Nm
1.29 markus 414: files,
415: even if the
416: .Nm ssh-agent
417: offers more identities.
418: The argument to this keyword must be
419: .Dq yes
420: or
421: .Dq no .
422: This option is intented for situations where
423: .Nm ssh-agent
424: offers many different identities.
425: The default is
426: .Dq no .
1.1 stevesk 427: .It Cm LocalForward
428: Specifies that a TCP/IP port on the local machine be forwarded over
429: the secure channel to the specified host and port from the remote machine.
430: The first argument must be a port number, and the second must be
431: .Ar host:port .
432: IPv6 addresses can be specified with an alternative syntax:
433: .Ar host/port .
434: Multiple forwardings may be specified, and additional
435: forwardings can be given on the command line.
436: Only the superuser can forward privileged ports.
437: .It Cm LogLevel
438: Gives the verbosity level that is used when logging messages from
439: .Nm ssh .
440: The possible values are:
441: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3.
1.7 jmc 442: The default is INFO.
443: DEBUG and DEBUG1 are equivalent.
444: DEBUG2 and DEBUG3 each specify higher levels of verbose output.
1.1 stevesk 445: .It Cm MACs
446: Specifies the MAC (message authentication code) algorithms
447: in order of preference.
448: The MAC algorithm is used in protocol version 2
449: for data integrity protection.
450: Multiple algorithms must be comma-separated.
451: The default is
452: .Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
453: .It Cm NoHostAuthenticationForLocalhost
454: This option can be used if the home directory is shared across machines.
455: In this case localhost will refer to a different machine on each of
456: the machines and the user will get many warnings about changed host keys.
457: However, this option disables host authentication for localhost.
458: The argument to this keyword must be
459: .Dq yes
460: or
461: .Dq no .
462: The default is to check the host key for localhost.
463: .It Cm NumberOfPasswordPrompts
464: Specifies the number of password prompts before giving up.
465: The argument to this keyword must be an integer.
466: Default is 3.
467: .It Cm PasswordAuthentication
468: Specifies whether to use password authentication.
469: The argument to this keyword must be
470: .Dq yes
471: or
472: .Dq no .
473: The default is
474: .Dq yes .
475: .It Cm Port
476: Specifies the port number to connect on the remote host.
477: Default is 22.
478: .It Cm PreferredAuthentications
479: Specifies the order in which the client should try protocol 2
1.11 jmc 480: authentication methods.
481: This allows a client to prefer one method (e.g.
1.1 stevesk 482: .Cm keyboard-interactive )
483: over another method (e.g.
484: .Cm password )
485: The default for this option is:
486: .Dq hostbased,publickey,keyboard-interactive,password .
487: .It Cm Protocol
488: Specifies the protocol versions
489: .Nm ssh
490: should support in order of preference.
491: The possible values are
492: .Dq 1
493: and
494: .Dq 2 .
495: Multiple versions must be comma-separated.
496: The default is
497: .Dq 2,1 .
498: This means that
499: .Nm ssh
500: tries version 2 and falls back to version 1
501: if version 2 is not available.
502: .It Cm ProxyCommand
503: Specifies the command to use to connect to the server.
504: The command
505: string extends to the end of the line, and is executed with
506: .Pa /bin/sh .
507: In the command string,
508: .Ql %h
509: will be substituted by the host name to
510: connect and
511: .Ql %p
512: by the port.
513: The command can be basically anything,
514: and should read from its standard input and write to its standard output.
515: It should eventually connect an
516: .Xr sshd 8
517: server running on some machine, or execute
518: .Ic sshd -i
519: somewhere.
520: Host key management will be done using the
521: HostName of the host being connected (defaulting to the name typed by
522: the user).
1.7 jmc 523: Setting the command to
524: .Dq none
1.6 markus 525: disables this option entirely.
1.1 stevesk 526: Note that
527: .Cm CheckHostIP
528: is not available for connects with a proxy command.
529: .Pp
530: .It Cm PubkeyAuthentication
531: Specifies whether to try public key authentication.
532: The argument to this keyword must be
533: .Dq yes
534: or
535: .Dq no .
536: The default is
537: .Dq yes .
538: This option applies to protocol version 2 only.
539: .It Cm RemoteForward
540: Specifies that a TCP/IP port on the remote machine be forwarded over
541: the secure channel to the specified host and port from the local machine.
542: The first argument must be a port number, and the second must be
543: .Ar host:port .
544: IPv6 addresses can be specified with an alternative syntax:
545: .Ar host/port .
546: Multiple forwardings may be specified, and additional
547: forwardings can be given on the command line.
548: Only the superuser can forward privileged ports.
549: .It Cm RhostsRSAAuthentication
550: Specifies whether to try rhosts based authentication with RSA host
551: authentication.
552: The argument must be
553: .Dq yes
554: or
555: .Dq no .
556: The default is
557: .Dq no .
558: This option applies to protocol version 1 only and requires
559: .Nm ssh
560: to be setuid root.
561: .It Cm RSAAuthentication
562: Specifies whether to try RSA authentication.
563: The argument to this keyword must be
564: .Dq yes
565: or
566: .Dq no .
567: RSA authentication will only be
568: attempted if the identity file exists, or an authentication agent is
569: running.
570: The default is
571: .Dq yes .
572: Note that this option applies to protocol version 1 only.
1.32 djm 573: .It Cm SendEnv
574: Specifies what variables from the local
575: .Xr environ 7
576: should be sent to the server.
577: Note that environment passing is only supported for protocol 2, the
1.33 djm 578: server must also support it, and the server must be configured to
579: accept these environment variables.
1.32 djm 580: Refer to
581: .Cm AcceptEnv
582: in
583: .Xr sshd_config 5
584: for how to configure the server.
585: Variables are specified by name, which may contain the wildcard characters
586: .Ql \&*
587: and
588: .Ql \&? .
1.33 djm 589: Multiple environment variables may be separated by whitespace or spread
1.32 djm 590: across multiple
591: .Cm SendEnv
592: directives.
593: The default is not to send any environment variables.
1.28 markus 594: .It Cm ServerAliveInterval
595: Sets a timeout interval in seconds after which if no data has been received
596: from the server,
597: .Nm ssh
598: will send a message through the encrypted
599: channel to request a response from the server.
600: The default
601: is 0, indicating that these messages will not be sent to the server.
602: This option applies to protocol version 2 only.
603: .It Cm ServerAliveCountMax
604: Sets the number of server alive messages (see above) which may be
605: sent without
606: .Nm ssh
607: receiving any messages back from the server.
608: If this threshold is reached while server alive messages are being sent,
609: .Nm ssh
610: will disconnect from the server, terminating the session.
611: It is important to note that the use of server alive messages is very
612: different from
613: .Cm TCPKeepAlive
614: (below).
615: The server alive messages are sent through the encrypted channel
616: and therefore will not be spoofable.
617: The TCP keepalive option enabled by
618: .Cm TCPKeepAlive
619: is spoofable.
620: The server alive mechanism is valuable when the client or
621: server depend on knowing when a connection has become inactive.
622: .Pp
623: The default value is 3.
624: If, for example,
625: .Cm ServerAliveInterval
626: (above) is set to 15, and
627: .Cm ServerAliveCountMax
628: is left at the default, if the server becomes unresponsive ssh
629: will disconnect after approximately 45 seconds.
1.1 stevesk 630: .It Cm SmartcardDevice
1.11 jmc 631: Specifies which smartcard device to use.
632: The argument to this keyword is the device
1.1 stevesk 633: .Nm ssh
634: should use to communicate with a smartcard used for storing the user's
1.11 jmc 635: private RSA key.
636: By default, no device is specified and smartcard support is not activated.
1.1 stevesk 637: .It Cm StrictHostKeyChecking
638: If this flag is set to
639: .Dq yes ,
640: .Nm ssh
641: will never automatically add host keys to the
642: .Pa $HOME/.ssh/known_hosts
643: file, and refuses to connect to hosts whose host key has changed.
644: This provides maximum protection against trojan horse attacks,
645: however, can be annoying when the
646: .Pa /etc/ssh/ssh_known_hosts
647: file is poorly maintained, or connections to new hosts are
648: frequently made.
649: This option forces the user to manually
650: add all new hosts.
651: If this flag is set to
652: .Dq no ,
653: .Nm ssh
654: will automatically add new host keys to the
655: user known hosts files.
656: If this flag is set to
657: .Dq ask ,
658: new host keys
659: will be added to the user known host files only after the user
660: has confirmed that is what they really want to do, and
661: .Nm ssh
662: will refuse to connect to hosts whose host key has changed.
663: The host keys of
664: known hosts will be verified automatically in all cases.
665: The argument must be
666: .Dq yes ,
667: .Dq no
668: or
669: .Dq ask .
670: The default is
671: .Dq ask .
1.26 markus 672: .It Cm TCPKeepAlive
673: Specifies whether the system should send TCP keepalive messages to the
674: other side.
675: If they are sent, death of the connection or crash of one
676: of the machines will be properly noticed.
677: However, this means that
678: connections will die if the route is down temporarily, and some people
679: find it annoying.
680: .Pp
681: The default is
682: .Dq yes
683: (to send TCP keepalive messages), and the client will notice
684: if the network goes down or the remote host dies.
685: This is important in scripts, and many users want it too.
686: .Pp
687: To disable TCP keepalive messages, the value should be set to
688: .Dq no .
1.1 stevesk 689: .It Cm UsePrivilegedPort
690: Specifies whether to use a privileged port for outgoing connections.
691: The argument must be
692: .Dq yes
693: or
694: .Dq no .
695: The default is
696: .Dq no .
1.4 stevesk 697: If set to
698: .Dq yes
699: .Nm ssh
700: must be setuid root.
1.1 stevesk 701: Note that this option must be set to
702: .Dq yes
1.17 markus 703: for
1.1 stevesk 704: .Cm RhostsRSAAuthentication
1.17 markus 705: with older servers.
1.1 stevesk 706: .It Cm User
707: Specifies the user to log in as.
708: This can be useful when a different user name is used on different machines.
709: This saves the trouble of
710: having to remember to give the user name on the command line.
711: .It Cm UserKnownHostsFile
712: Specifies a file to use for the user
713: host key database instead of
714: .Pa $HOME/.ssh/known_hosts .
1.8 jakob 715: .It Cm VerifyHostKeyDNS
716: Specifies whether to verify the remote key using DNS and SSHFP resource
717: records.
1.24 jakob 718: If this option is set to
719: .Dq yes ,
1.25 jmc 720: the client will implicitly trust keys that match a secure fingerprint
1.24 jakob 721: from DNS.
722: Insecure fingerprints will be handled as if this option was set to
723: .Dq ask .
724: If this option is set to
725: .Dq ask ,
726: information on fingerprint match will be displayed, but the user will still
727: need to confirm new host keys according to the
728: .Cm StrictHostKeyChecking
729: option.
730: The argument must be
731: .Dq yes ,
732: .Dq no
1.25 jmc 733: or
734: .Dq ask .
1.8 jakob 735: The default is
736: .Dq no .
1.12 jakob 737: Note that this option applies to protocol version 2 only.
1.1 stevesk 738: .It Cm XAuthLocation
1.5 stevesk 739: Specifies the full pathname of the
1.1 stevesk 740: .Xr xauth 1
741: program.
742: The default is
743: .Pa /usr/X11R6/bin/xauth .
744: .El
745: .Sh FILES
746: .Bl -tag -width Ds
747: .It Pa $HOME/.ssh/config
748: This is the per-user configuration file.
749: The format of this file is described above.
750: This file is used by the
751: .Nm ssh
752: client.
1.30 djm 753: Because of the potential for abuse, this file must have strict permissions:
754: read/write for the user, and not accessible by others.
1.1 stevesk 755: .It Pa /etc/ssh/ssh_config
756: Systemwide configuration file.
757: This file provides defaults for those
758: values that are not specified in the user's configuration file, and
759: for those users who do not have a configuration file.
760: This file must be world-readable.
761: .El
1.13 jmc 762: .Sh SEE ALSO
763: .Xr ssh 1
1.1 stevesk 764: .Sh AUTHORS
765: OpenSSH is a derivative of the original and free
766: ssh 1.2.12 release by Tatu Ylonen.
767: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
768: Theo de Raadt and Dug Song
769: removed many bugs, re-added newer features and
770: created OpenSSH.
771: Markus Friedl contributed the support for SSH
772: protocol versions 1.5 and 2.0.
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