Annotation of src/usr.bin/ssh/sshd_config.5, Revision 1.20
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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1.20 ! djm 37: .\" $OpenBSD: sshd_config.5,v 1.19 2003/06/10 09:12:12 jmc Exp $
1.1 stevesk 38: .Dd September 25, 1999
39: .Dt SSHD_CONFIG 5
40: .Os
41: .Sh NAME
42: .Nm sshd_config
43: .Nd OpenSSH SSH daemon configuration file
44: .Sh SYNOPSIS
45: .Bl -tag -width Ds -compact
46: .It Pa /etc/ssh/sshd_config
47: .El
48: .Sh DESCRIPTION
49: .Nm sshd
50: reads configuration data from
51: .Pa /etc/ssh/sshd_config
52: (or the file specified with
53: .Fl f
54: on the command line).
55: The file contains keyword-argument pairs, one per line.
56: Lines starting with
57: .Ql #
58: and empty lines are interpreted as comments.
59: .Pp
60: The possible
61: keywords and their meanings are as follows (note that
62: keywords are case-insensitive and arguments are case-sensitive):
63: .Bl -tag -width Ds
64: .It Cm AFSTokenPassing
65: Specifies whether an AFS token may be forwarded to the server.
66: Default is
67: .Dq no .
68: .It Cm AllowGroups
69: This keyword can be followed by a list of group name patterns, separated
70: by spaces.
71: If specified, login is allowed only for users whose primary
72: group or supplementary group list matches one of the patterns.
73: .Ql \&*
74: and
1.16 mouring 75: .Ql \&?
1.1 stevesk 76: can be used as
77: wildcards in the patterns.
78: Only group names are valid; a numerical group ID is not recognized.
79: By default, login is allowed for all groups.
80: .Pp
81: .It Cm AllowTcpForwarding
82: Specifies whether TCP forwarding is permitted.
83: The default is
84: .Dq yes .
85: Note that disabling TCP forwarding does not improve security unless
86: users are also denied shell access, as they can always install their
87: own forwarders.
88: .Pp
89: .It Cm AllowUsers
90: This keyword can be followed by a list of user name patterns, separated
91: by spaces.
1.14 jmc 92: If specified, login is allowed only for user names that
1.1 stevesk 93: match one of the patterns.
94: .Ql \&*
95: and
1.16 mouring 96: .Ql \&?
1.1 stevesk 97: can be used as
98: wildcards in the patterns.
99: Only user names are valid; a numerical user ID is not recognized.
100: By default, login is allowed for all users.
101: If the pattern takes the form USER@HOST then USER and HOST
102: are separately checked, restricting logins to particular
103: users from particular hosts.
104: .Pp
105: .It Cm AuthorizedKeysFile
106: Specifies the file that contains the public keys that can be used
107: for user authentication.
108: .Cm AuthorizedKeysFile
109: may contain tokens of the form %T which are substituted during connection
1.17 jmc 110: set-up.
111: The following tokens are defined: %% is replaced by a literal '%',
1.1 stevesk 112: %h is replaced by the home directory of the user being authenticated and
113: %u is replaced by the username of that user.
114: After expansion,
115: .Cm AuthorizedKeysFile
116: is taken to be an absolute path or one relative to the user's home
117: directory.
118: The default is
119: .Dq .ssh/authorized_keys .
120: .It Cm Banner
121: In some jurisdictions, sending a warning message before authentication
122: may be relevant for getting legal protection.
123: The contents of the specified file are sent to the remote user before
124: authentication is allowed.
125: This option is only available for protocol version 2.
126: By default, no banner is displayed.
127: .Pp
128: .It Cm ChallengeResponseAuthentication
129: Specifies whether challenge response authentication is allowed.
130: All authentication styles from
131: .Xr login.conf 5
132: are supported.
133: The default is
134: .Dq yes .
135: .It Cm Ciphers
136: Specifies the ciphers allowed for protocol version 2.
137: Multiple ciphers must be comma-separated.
138: The default is
139: .Pp
140: .Bd -literal
141: ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
1.20 ! djm 142: aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr''
1.1 stevesk 143: .Ed
144: .It Cm ClientAliveInterval
145: Sets a timeout interval in seconds after which if no data has been received
146: from the client,
147: .Nm sshd
148: will send a message through the encrypted
149: channel to request a response from the client.
150: The default
151: is 0, indicating that these messages will not be sent to the client.
152: This option applies to protocol version 2 only.
153: .It Cm ClientAliveCountMax
154: Sets the number of client alive messages (see above) which may be
155: sent without
156: .Nm sshd
1.17 jmc 157: receiving any messages back from the client.
158: If this threshold is reached while client alive messages are being sent,
1.1 stevesk 159: .Nm sshd
1.17 jmc 160: will disconnect the client, terminating the session.
161: It is important to note that the use of client alive messages is very
162: different from
1.1 stevesk 163: .Cm KeepAlive
1.17 jmc 164: (below).
165: The client alive messages are sent through the encrypted channel
166: and therefore will not be spoofable.
167: The TCP keepalive option enabled by
1.1 stevesk 168: .Cm KeepAlive
1.17 jmc 169: is spoofable.
170: The client alive mechanism is valuable when the client or
1.1 stevesk 171: server depend on knowing when a connection has become inactive.
172: .Pp
1.17 jmc 173: The default value is 3.
174: If
1.1 stevesk 175: .Cm ClientAliveInterval
176: (above) is set to 15, and
177: .Cm ClientAliveCountMax
178: is left at the default, unresponsive ssh clients
179: will be disconnected after approximately 45 seconds.
1.3 markus 180: .It Cm Compression
181: Specifies whether compression is allowed.
182: The argument must be
183: .Dq yes
184: or
185: .Dq no .
186: The default is
187: .Dq yes .
1.1 stevesk 188: .It Cm DenyGroups
189: This keyword can be followed by a list of group name patterns, separated
190: by spaces.
191: Login is disallowed for users whose primary group or supplementary
192: group list matches one of the patterns.
193: .Ql \&*
194: and
1.16 mouring 195: .Ql \&?
1.1 stevesk 196: can be used as
197: wildcards in the patterns.
198: Only group names are valid; a numerical group ID is not recognized.
199: By default, login is allowed for all groups.
200: .Pp
201: .It Cm DenyUsers
202: This keyword can be followed by a list of user name patterns, separated
203: by spaces.
204: Login is disallowed for user names that match one of the patterns.
205: .Ql \&*
206: and
1.16 mouring 207: .Ql \&?
1.1 stevesk 208: can be used as wildcards in the patterns.
209: Only user names are valid; a numerical user ID is not recognized.
210: By default, login is allowed for all users.
211: If the pattern takes the form USER@HOST then USER and HOST
212: are separately checked, restricting logins to particular
213: users from particular hosts.
214: .It Cm GatewayPorts
215: Specifies whether remote hosts are allowed to connect to ports
216: forwarded for the client.
217: By default,
218: .Nm sshd
1.15 jmc 219: binds remote port forwardings to the loopback address.
220: This prevents other remote hosts from connecting to forwarded ports.
1.1 stevesk 221: .Cm GatewayPorts
222: can be used to specify that
223: .Nm sshd
224: should bind remote port forwardings to the wildcard address,
225: thus allowing remote hosts to connect to forwarded ports.
226: The argument must be
227: .Dq yes
228: or
229: .Dq no .
230: The default is
231: .Dq no .
232: .It Cm HostbasedAuthentication
233: Specifies whether rhosts or /etc/hosts.equiv authentication together
234: with successful public key client host authentication is allowed
235: (hostbased authentication).
236: This option is similar to
237: .Cm RhostsRSAAuthentication
238: and applies to protocol version 2 only.
239: The default is
240: .Dq no .
241: .It Cm HostKey
242: Specifies a file containing a private host key
243: used by SSH.
244: The default is
245: .Pa /etc/ssh/ssh_host_key
246: for protocol version 1, and
247: .Pa /etc/ssh/ssh_host_rsa_key
248: and
249: .Pa /etc/ssh/ssh_host_dsa_key
250: for protocol version 2.
251: Note that
252: .Nm sshd
253: will refuse to use a file if it is group/world-accessible.
254: It is possible to have multiple host key files.
255: .Dq rsa1
256: keys are used for version 1 and
257: .Dq dsa
258: or
259: .Dq rsa
260: are used for version 2 of the SSH protocol.
261: .It Cm IgnoreRhosts
262: Specifies that
263: .Pa .rhosts
264: and
265: .Pa .shosts
266: files will not be used in
267: .Cm RhostsAuthentication ,
268: .Cm RhostsRSAAuthentication
269: or
270: .Cm HostbasedAuthentication .
271: .Pp
272: .Pa /etc/hosts.equiv
273: and
274: .Pa /etc/shosts.equiv
275: are still used.
276: The default is
277: .Dq yes .
278: .It Cm IgnoreUserKnownHosts
279: Specifies whether
280: .Nm sshd
281: should ignore the user's
282: .Pa $HOME/.ssh/known_hosts
283: during
284: .Cm RhostsRSAAuthentication
285: or
286: .Cm HostbasedAuthentication .
287: The default is
288: .Dq no .
289: .It Cm KeepAlive
290: Specifies whether the system should send TCP keepalive messages to the
291: other side.
292: If they are sent, death of the connection or crash of one
293: of the machines will be properly noticed.
294: However, this means that
295: connections will die if the route is down temporarily, and some people
296: find it annoying.
297: On the other hand, if keepalives are not sent,
298: sessions may hang indefinitely on the server, leaving
299: .Dq ghost
300: users and consuming server resources.
301: .Pp
302: The default is
303: .Dq yes
304: (to send keepalives), and the server will notice
305: if the network goes down or the client host crashes.
306: This avoids infinitely hanging sessions.
307: .Pp
308: To disable keepalives, the value should be set to
309: .Dq no .
310: .It Cm KerberosAuthentication
311: Specifies whether Kerberos authentication is allowed.
312: This can be in the form of a Kerberos ticket, or if
313: .Cm PasswordAuthentication
314: is yes, the password provided by the user will be validated through
315: the Kerberos KDC.
316: To use this option, the server needs a
317: Kerberos servtab which allows the verification of the KDC's identity.
318: Default is
319: .Dq no .
320: .It Cm KerberosOrLocalPasswd
321: If set then if password authentication through Kerberos fails then
322: the password will be validated via any additional local mechanism
323: such as
324: .Pa /etc/passwd .
325: Default is
326: .Dq yes .
327: .It Cm KerberosTgtPassing
328: Specifies whether a Kerberos TGT may be forwarded to the server.
329: Default is
330: .Dq no ,
331: as this only works when the Kerberos KDC is actually an AFS kaserver.
332: .It Cm KerberosTicketCleanup
333: Specifies whether to automatically destroy the user's ticket cache
334: file on logout.
335: Default is
336: .Dq yes .
337: .It Cm KeyRegenerationInterval
338: In protocol version 1, the ephemeral server key is automatically regenerated
339: after this many seconds (if it has been used).
340: The purpose of regeneration is to prevent
341: decrypting captured sessions by later breaking into the machine and
342: stealing the keys.
343: The key is never stored anywhere.
344: If the value is 0, the key is never regenerated.
345: The default is 3600 (seconds).
346: .It Cm ListenAddress
347: Specifies the local addresses
348: .Nm sshd
349: should listen on.
350: The following forms may be used:
351: .Pp
352: .Bl -item -offset indent -compact
353: .It
354: .Cm ListenAddress
355: .Sm off
356: .Ar host No | Ar IPv4_addr No | Ar IPv6_addr
357: .Sm on
358: .It
359: .Cm ListenAddress
360: .Sm off
361: .Ar host No | Ar IPv4_addr No : Ar port
362: .Sm on
363: .It
364: .Cm ListenAddress
365: .Sm off
366: .Oo
367: .Ar host No | Ar IPv6_addr Oc : Ar port
368: .Sm on
369: .El
370: .Pp
371: If
372: .Ar port
373: is not specified,
374: .Nm sshd
375: will listen on the address and all prior
376: .Cm Port
1.17 jmc 377: options specified.
378: The default is to listen on all local addresses.
1.15 jmc 379: Multiple
1.1 stevesk 380: .Cm ListenAddress
1.17 jmc 381: options are permitted.
382: Additionally, any
1.1 stevesk 383: .Cm Port
384: options must precede this option for non port qualified addresses.
385: .It Cm LoginGraceTime
386: The server disconnects after this time if the user has not
387: successfully logged in.
388: If the value is 0, there is no time limit.
1.12 stevesk 389: The default is 120 seconds.
1.1 stevesk 390: .It Cm LogLevel
391: Gives the verbosity level that is used when logging messages from
392: .Nm sshd .
393: The possible values are:
394: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3.
1.15 jmc 395: The default is INFO.
396: DEBUG and DEBUG1 are equivalent.
397: DEBUG2 and DEBUG3 each specify higher levels of debugging output.
398: Logging with a DEBUG level violates the privacy of users and is not recommended.
1.1 stevesk 399: .It Cm MACs
400: Specifies the available MAC (message authentication code) algorithms.
401: The MAC algorithm is used in protocol version 2
402: for data integrity protection.
403: Multiple algorithms must be comma-separated.
404: The default is
405: .Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
406: .It Cm MaxStartups
407: Specifies the maximum number of concurrent unauthenticated connections to the
408: .Nm sshd
409: daemon.
410: Additional connections will be dropped until authentication succeeds or the
411: .Cm LoginGraceTime
412: expires for a connection.
413: The default is 10.
414: .Pp
415: Alternatively, random early drop can be enabled by specifying
416: the three colon separated values
417: .Dq start:rate:full
418: (e.g., "10:30:60").
419: .Nm sshd
420: will refuse connection attempts with a probability of
421: .Dq rate/100
422: (30%)
423: if there are currently
424: .Dq start
425: (10)
426: unauthenticated connections.
427: The probability increases linearly and all connection attempts
428: are refused if the number of unauthenticated connections reaches
429: .Dq full
430: (60).
431: .It Cm PasswordAuthentication
432: Specifies whether password authentication is allowed.
433: The default is
434: .Dq yes .
435: .It Cm PermitEmptyPasswords
436: When password authentication is allowed, it specifies whether the
437: server allows login to accounts with empty password strings.
438: The default is
439: .Dq no .
440: .It Cm PermitRootLogin
441: Specifies whether root can login using
442: .Xr ssh 1 .
443: The argument must be
444: .Dq yes ,
445: .Dq without-password ,
446: .Dq forced-commands-only
447: or
448: .Dq no .
449: The default is
450: .Dq yes .
451: .Pp
452: If this option is set to
453: .Dq without-password
454: password authentication is disabled for root.
455: .Pp
456: If this option is set to
457: .Dq forced-commands-only
458: root login with public key authentication will be allowed,
459: but only if the
460: .Ar command
461: option has been specified
462: (which may be useful for taking remote backups even if root login is
1.17 jmc 463: normally not allowed).
464: All other authentication methods are disabled for root.
1.1 stevesk 465: .Pp
466: If this option is set to
467: .Dq no
468: root is not allowed to login.
1.6 markus 469: .It Cm PermitUserEnvironment
470: Specifies whether
471: .Pa ~/.ssh/environment
1.9 stevesk 472: and
1.6 markus 473: .Cm environment=
474: options in
475: .Pa ~/.ssh/authorized_keys
1.9 stevesk 476: are processed by
477: .Nm sshd .
1.6 markus 478: The default is
479: .Dq no .
1.9 stevesk 480: Enabling environment processing may enable users to bypass access
481: restrictions in some configurations using mechanisms such as
482: .Ev LD_PRELOAD .
1.1 stevesk 483: .It Cm PidFile
1.4 stevesk 484: Specifies the file that contains the process ID of the
1.1 stevesk 485: .Nm sshd
486: daemon.
487: The default is
488: .Pa /var/run/sshd.pid .
489: .It Cm Port
490: Specifies the port number that
491: .Nm sshd
492: listens on.
493: The default is 22.
494: Multiple options of this type are permitted.
495: See also
496: .Cm ListenAddress .
497: .It Cm PrintLastLog
498: Specifies whether
499: .Nm sshd
500: should print the date and time when the user last logged in.
501: The default is
502: .Dq yes .
503: .It Cm PrintMotd
504: Specifies whether
505: .Nm sshd
506: should print
507: .Pa /etc/motd
508: when a user logs in interactively.
509: (On some systems it is also printed by the shell,
510: .Pa /etc/profile ,
511: or equivalent.)
512: The default is
513: .Dq yes .
514: .It Cm Protocol
515: Specifies the protocol versions
516: .Nm sshd
1.5 stevesk 517: supports.
1.1 stevesk 518: The possible values are
519: .Dq 1
520: and
521: .Dq 2 .
522: Multiple versions must be comma-separated.
523: The default is
524: .Dq 2,1 .
1.5 stevesk 525: Note that the order of the protocol list does not indicate preference,
526: because the client selects among multiple protocol versions offered
527: by the server.
528: Specifying
529: .Dq 2,1
530: is identical to
531: .Dq 1,2 .
1.1 stevesk 532: .It Cm PubkeyAuthentication
533: Specifies whether public key authentication is allowed.
534: The default is
535: .Dq yes .
536: Note that this option applies to protocol version 2 only.
537: .It Cm RhostsAuthentication
538: Specifies whether authentication using rhosts or /etc/hosts.equiv
539: files is sufficient.
540: Normally, this method should not be permitted because it is insecure.
541: .Cm RhostsRSAAuthentication
542: should be used
543: instead, because it performs RSA-based host authentication in addition
544: to normal rhosts or /etc/hosts.equiv authentication.
545: The default is
546: .Dq no .
547: This option applies to protocol version 1 only.
548: .It Cm RhostsRSAAuthentication
549: Specifies whether rhosts or /etc/hosts.equiv authentication together
550: with successful RSA host authentication is allowed.
551: The default is
552: .Dq no .
553: This option applies to protocol version 1 only.
554: .It Cm RSAAuthentication
555: Specifies whether pure RSA authentication is allowed.
556: The default is
557: .Dq yes .
558: This option applies to protocol version 1 only.
559: .It Cm ServerKeyBits
560: Defines the number of bits in the ephemeral protocol version 1 server key.
561: The minimum value is 512, and the default is 768.
562: .It Cm StrictModes
563: Specifies whether
564: .Nm sshd
565: should check file modes and ownership of the
566: user's files and home directory before accepting login.
567: This is normally desirable because novices sometimes accidentally leave their
568: directory or files world-writable.
569: The default is
570: .Dq yes .
571: .It Cm Subsystem
572: Configures an external subsystem (e.g., file transfer daemon).
573: Arguments should be a subsystem name and a command to execute upon subsystem
574: request.
575: The command
576: .Xr sftp-server 8
577: implements the
578: .Dq sftp
579: file transfer subsystem.
580: By default no subsystems are defined.
581: Note that this option applies to protocol version 2 only.
582: .It Cm SyslogFacility
583: Gives the facility code that is used when logging messages from
584: .Nm sshd .
585: The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
586: LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
587: The default is AUTH.
1.18 markus 588: .It Cm UseDNS
589: Specifies whether
590: .Nm sshd
591: should lookup the remote host name and check that
592: the resolved host name for the remote IP address maps back to the
593: very same IP address.
594: The default is
595: .Dq yes .
1.1 stevesk 596: .It Cm UseLogin
597: Specifies whether
598: .Xr login 1
599: is used for interactive login sessions.
600: The default is
601: .Dq no .
602: Note that
603: .Xr login 1
604: is never used for remote command execution.
605: Note also, that if this is enabled,
606: .Cm X11Forwarding
607: will be disabled because
608: .Xr login 1
609: does not know how to handle
610: .Xr xauth 1
1.15 jmc 611: cookies.
612: If
1.1 stevesk 613: .Cm UsePrivilegeSeparation
614: is specified, it will be disabled after authentication.
615: .It Cm UsePrivilegeSeparation
616: Specifies whether
617: .Nm sshd
1.2 stevesk 618: separates privileges by creating an unprivileged child process
1.15 jmc 619: to deal with incoming network traffic.
620: After successful authentication, another process will be created that has
621: the privilege of the authenticated user.
622: The goal of privilege separation is to prevent privilege
1.1 stevesk 623: escalation by containing any corruption within the unprivileged processes.
624: The default is
625: .Dq yes .
626: .It Cm X11DisplayOffset
627: Specifies the first display number available for
628: .Nm sshd Ns 's
629: X11 forwarding.
630: This prevents
631: .Nm sshd
632: from interfering with real X11 servers.
633: The default is 10.
634: .It Cm X11Forwarding
635: Specifies whether X11 forwarding is permitted.
1.13 stevesk 636: The argument must be
637: .Dq yes
638: or
639: .Dq no .
1.1 stevesk 640: The default is
641: .Dq no .
1.13 stevesk 642: .Pp
643: When X11 forwarding is enabled, there may be additional exposure to
644: the server and to client displays if the
645: .Nm sshd
646: proxy display is configured to listen on the wildcard address (see
647: .Cm X11UseLocalhost
648: below), however this is not the default.
649: Additionally, the authentication spoofing and authentication data
650: verification and substitution occur on the client side.
651: The security risk of using X11 forwarding is that the client's X11
652: display server may be exposed to attack when the ssh client requests
653: forwarding (see the warnings for
654: .Cm ForwardX11
655: in
1.19 jmc 656: .Xr ssh_config 5 ) .
1.13 stevesk 657: A system administrator may have a stance in which they want to
658: protect clients that may expose themselves to attack by unwittingly
659: requesting X11 forwarding, which can warrant a
660: .Dq no
661: setting.
662: .Pp
663: Note that disabling X11 forwarding does not prevent users from
664: forwarding X11 traffic, as users can always install their own forwarders.
1.1 stevesk 665: X11 forwarding is automatically disabled if
666: .Cm UseLogin
667: is enabled.
668: .It Cm X11UseLocalhost
669: Specifies whether
670: .Nm sshd
671: should bind the X11 forwarding server to the loopback address or to
1.15 jmc 672: the wildcard address.
673: By default,
1.1 stevesk 674: .Nm sshd
675: binds the forwarding server to the loopback address and sets the
676: hostname part of the
677: .Ev DISPLAY
678: environment variable to
679: .Dq localhost .
1.8 stevesk 680: This prevents remote hosts from connecting to the proxy display.
1.1 stevesk 681: However, some older X11 clients may not function with this
682: configuration.
683: .Cm X11UseLocalhost
684: may be set to
685: .Dq no
686: to specify that the forwarding server should be bound to the wildcard
687: address.
688: The argument must be
689: .Dq yes
690: or
691: .Dq no .
692: The default is
693: .Dq yes .
694: .It Cm XAuthLocation
1.11 stevesk 695: Specifies the full pathname of the
1.1 stevesk 696: .Xr xauth 1
697: program.
698: The default is
699: .Pa /usr/X11R6/bin/xauth .
700: .El
701: .Ss Time Formats
702: .Nm sshd
703: command-line arguments and configuration file options that specify time
704: may be expressed using a sequence of the form:
705: .Sm off
1.7 stevesk 706: .Ar time Op Ar qualifier ,
1.1 stevesk 707: .Sm on
708: where
709: .Ar time
710: is a positive integer value and
711: .Ar qualifier
712: is one of the following:
713: .Pp
714: .Bl -tag -width Ds -compact -offset indent
715: .It Cm <none>
716: seconds
717: .It Cm s | Cm S
718: seconds
719: .It Cm m | Cm M
720: minutes
721: .It Cm h | Cm H
722: hours
723: .It Cm d | Cm D
724: days
725: .It Cm w | Cm W
726: weeks
727: .El
728: .Pp
729: Each member of the sequence is added together to calculate
730: the total time value.
731: .Pp
732: Time format examples:
733: .Pp
734: .Bl -tag -width Ds -compact -offset indent
735: .It 600
736: 600 seconds (10 minutes)
737: .It 10m
738: 10 minutes
739: .It 1h30m
740: 1 hour 30 minutes (90 minutes)
741: .El
742: .Sh FILES
743: .Bl -tag -width Ds
744: .It Pa /etc/ssh/sshd_config
745: Contains configuration data for
746: .Nm sshd .
747: This file should be writable by root only, but it is recommended
748: (though not necessary) that it be world-readable.
749: .El
1.19 jmc 750: .Sh SEE ALSO
751: .Xr sshd 8
1.1 stevesk 752: .Sh AUTHORS
753: OpenSSH is a derivative of the original and free
754: ssh 1.2.12 release by Tatu Ylonen.
755: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
756: Theo de Raadt and Dug Song
757: removed many bugs, re-added newer features and
758: created OpenSSH.
759: Markus Friedl contributed the support for SSH
760: protocol versions 1.5 and 2.0.
761: Niels Provos and Markus Friedl contributed support
762: for privilege separation.
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