3 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 .\" All rights reserved
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".
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.
17 .\" Redistribution and use in source and binary forms, with or without
18 .\" modification, are permitted provided that the following conditions
20 .\" 1. Redistributions of source code must retain the above copyright
21 .\" notice, this list of conditions and the following disclaimer.
22 .\" 2. Redistributions in binary form must reproduce the above copyright
23 .\" notice, this list of conditions and the following disclaimer in the
24 .\" documentation and/or other materials provided with the distribution.
26 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 .\" $OpenBSD: sshd_config.5,v 1.125 2010/06/30 07:28:34 jmc Exp $
38 .Dd $Mdocdate: June 30 2010 $
43 .Nd OpenSSH SSH daemon configuration file
45 .Nm /etc/ssh/sshd_config
48 reads configuration data from
49 .Pa /etc/ssh/sshd_config
50 (or the file specified with
53 The file contains keyword-argument pairs, one per line.
56 and empty lines are interpreted as comments.
57 Arguments may optionally be enclosed in double quotes
59 in order to represent arguments containing spaces.
62 keywords and their meanings are as follows (note that
63 keywords are case-insensitive and arguments are case-sensitive):
66 Specifies what environment variables sent by the client will be copied into
73 for how to configure the client.
74 Note that environment passing is only supported for protocol 2.
75 Variables are specified by name, which may contain the wildcard characters
79 Multiple environment variables may be separated by whitespace or spread
83 Be warned that some environment variables could be used to bypass restricted
85 For this reason, care should be taken in the use of this directive.
86 The default is not to accept any environment variables.
88 Specifies which address family should be used by
98 .It Cm AllowAgentForwarding
101 forwarding is permitted.
104 Note that disabling agent forwarding does not improve security
105 unless users are also denied shell access, as they can always install
106 their own forwarders.
108 This keyword can be followed by a list of group name patterns, separated
110 If specified, login is allowed only for users whose primary
111 group or supplementary group list matches one of the patterns.
112 Only group names are valid; a numerical group ID is not recognized.
113 By default, login is allowed for all groups.
114 The allow/deny directives are processed in the following order:
125 for more information on patterns.
126 .It Cm AllowTcpForwarding
127 Specifies whether TCP forwarding is permitted.
130 Note that disabling TCP forwarding does not improve security unless
131 users are also denied shell access, as they can always install their
134 This keyword can be followed by a list of user name patterns, separated
136 If specified, login is allowed only for user names that
137 match one of the patterns.
138 Only user names are valid; a numerical user ID is not recognized.
139 By default, login is allowed for all users.
140 If the pattern takes the form USER@HOST then USER and HOST
141 are separately checked, restricting logins to particular
142 users from particular hosts.
143 The allow/deny directives are processed in the following order:
154 for more information on patterns.
155 .It Cm AuthorizedKeysFile
156 Specifies the file that contains the public keys that can be used
157 for user authentication.
158 The format is described in the
159 .Sx AUTHORIZED_KEYS FILE FORMAT
162 .Cm AuthorizedKeysFile
163 may contain tokens of the form %T which are substituted during connection
165 The following tokens are defined: %% is replaced by a literal '%',
166 %h is replaced by the home directory of the user being authenticated, and
167 %u is replaced by the username of that user.
169 .Cm AuthorizedKeysFile
170 is taken to be an absolute path or one relative to the user's home
173 .Dq .ssh/authorized_keys .
174 .It Cm AuthorizedPrincipalsFile
175 Specifies a file that lists principal names that are accepted for
176 certificate authentication.
177 When using certificates signed by a key listed in
178 .Cm TrustedUserCAKeys ,
179 this file lists names, one of which must appear in the certificate for it
180 to be accepted for authentication.
181 Names are listed one per line preceded by key options (as described
183 .Sx AUTHORIZED_KEYS FILE FORMAT
186 Empty lines and comments starting with
190 .Cm AuthorizedPrincipalsFile
191 may contain tokens of the form %T which are substituted during connection
193 The following tokens are defined: %% is replaced by a literal '%',
194 %h is replaced by the home directory of the user being authenticated, and
195 %u is replaced by the username of that user.
197 .Cm AuthorizedPrincipalsFile
198 is taken to be an absolute path or one relative to the user's home
201 The default is not to use a principals file \(en in this case, the username
202 of the user must appear in a certificate's principals list for it to be
205 .Cm AuthorizedPrincipalsFile
206 is only used when authentication proceeds using a CA listed in
207 .Cm TrustedUserCAKeys
208 and is not consulted for certification authorities trusted via
209 .Pa ~/.ssh/authorized_keys ,
212 key option offers a similar facility (see
216 The contents of the specified file are sent to the remote user before
217 authentication is allowed.
220 then no banner is displayed.
221 This option is only available for protocol version 2.
222 By default, no banner is displayed.
223 .It Cm ChallengeResponseAuthentication
224 Specifies whether challenge-response authentication is allowed.
227 this controls the use of PAM (see
230 Note that this affects the effectiveness of the
231 .Cm PasswordAuthentication
237 .It Cm ChrootDirectory
238 Specifies the pathname of a directory to
240 to after authentication.
241 All components of the pathname must be root-owned directories that are
242 not writable by any other user or group.
245 changes the working directory to the user's home directory.
247 The pathname may contain the following tokens that are expanded at runtime once
248 the connecting user has been authenticated: %% is replaced by a literal '%',
249 %h is replaced by the home directory of the user being authenticated, and
250 %u is replaced by the username of that user.
254 must contain the necessary files and directories to support the
256 For an interactive session this requires at least a shell, typically
270 For file transfer sessions using
272 no additional configuration of the environment is necessary if the
273 in-process sftp server is used,
274 though sessions which use logging do require
276 inside the chroot directory (see
280 The default is not to
283 Specifies the ciphers allowed for protocol version 2.
284 Multiple ciphers must be comma-separated.
285 The supported ciphers are
300 .Bd -literal -offset 3n
301 aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
302 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
305 .It Cm ClientAliveCountMax
306 Sets the number of client alive messages (see below) which may be
309 receiving any messages back from the client.
310 If this threshold is reached while client alive messages are being sent,
311 sshd will disconnect the client, terminating the session.
312 It is important to note that the use of client alive messages is very
316 The client alive messages are sent through the encrypted channel
317 and therefore will not be spoofable.
318 The TCP keepalive option enabled by
321 The client alive mechanism is valuable when the client or
322 server depend on knowing when a connection has become inactive.
324 The default value is 3.
326 .Cm ClientAliveInterval
327 (see below) is set to 15, and
328 .Cm ClientAliveCountMax
329 is left at the default, unresponsive SSH clients
330 will be disconnected after approximately 45 seconds.
331 This option applies to protocol version 2 only.
332 .It Cm ClientAliveInterval
333 Sets a timeout interval in seconds after which if no data has been received
336 will send a message through the encrypted
337 channel to request a response from the client.
339 is 0, indicating that these messages will not be sent to the client.
340 This option applies to protocol version 2 only.
342 Specifies whether compression is allowed, or delayed until
343 the user has authenticated successfully.
352 This keyword can be followed by a list of group name patterns, separated
354 Login is disallowed for users whose primary group or supplementary
355 group list matches one of the patterns.
356 Only group names are valid; a numerical group ID is not recognized.
357 By default, login is allowed for all groups.
358 The allow/deny directives are processed in the following order:
369 for more information on patterns.
371 This keyword can be followed by a list of user name patterns, separated
373 Login is disallowed for user names that match one of the patterns.
374 Only user names are valid; a numerical user ID is not recognized.
375 By default, login is allowed for all users.
376 If the pattern takes the form USER@HOST then USER and HOST
377 are separately checked, restricting logins to particular
378 users from particular hosts.
379 The allow/deny directives are processed in the following order:
390 for more information on patterns.
392 Forces the execution of the command specified by
394 ignoring any command supplied by the client and
397 The command is invoked by using the user's login shell with the -c option.
398 This applies to shell, command, or subsystem execution.
399 It is most useful inside a
402 The command originally supplied by the client is available in the
403 .Ev SSH_ORIGINAL_COMMAND
404 environment variable.
405 Specifying a command of
407 will force the use of an in-process sftp server that requires no support
409 .Cm ChrootDirectory .
411 Specifies whether remote hosts are allowed to connect to ports
412 forwarded for the client.
415 binds remote port forwardings to the loopback address.
416 This prevents other remote hosts from connecting to forwarded ports.
418 can be used to specify that sshd
419 should allow remote port forwardings to bind to non-loopback addresses, thus
420 allowing other hosts to connect.
423 to force remote port forwardings to be available to the local host only,
425 to force remote port forwardings to bind to the wildcard address, or
427 to allow the client to select the address to which the forwarding is bound.
430 .It Cm GSSAPIAuthentication
431 Specifies whether user authentication based on GSSAPI is allowed.
434 Note that this option applies to protocol version 2 only.
435 .It Cm GSSAPICleanupCredentials
436 Specifies whether to automatically destroy the user's credentials cache
440 Note that this option applies to protocol version 2 only.
441 .It Cm HostbasedAuthentication
442 Specifies whether rhosts or /etc/hosts.equiv authentication together
443 with successful public key client host authentication is allowed
444 (host-based authentication).
445 This option is similar to
446 .Cm RhostsRSAAuthentication
447 and applies to protocol version 2 only.
450 .It Cm HostbasedUsesNameFromPacketOnly
451 Specifies whether or not the server will attempt to perform a reverse
452 name lookup when matching the name in the
458 .Cm HostbasedAuthentication .
463 uses the name supplied by the client rather than
464 attempting to resolve the name from the TCP connection itself.
467 .It Cm HostCertificate
468 Specifies a file containing a public host certificate.
469 The certificate's public key must match a private host key already specified
472 The default behaviour of
474 is not to load any certificates.
476 Specifies a file containing a private host key
479 .Pa /etc/ssh/ssh_host_key
480 for protocol version 1, and
481 .Pa /etc/ssh/ssh_host_rsa_key
483 .Pa /etc/ssh/ssh_host_dsa_key
484 for protocol version 2.
487 will refuse to use a file if it is group/world-accessible.
488 It is possible to have multiple host key files.
490 keys are used for version 1 and
494 are used for version 2 of the SSH protocol.
500 files will not be used in
501 .Cm RhostsRSAAuthentication
503 .Cm HostbasedAuthentication .
507 .Pa /etc/ssh/shosts.equiv
511 .It Cm IgnoreUserKnownHosts
514 should ignore the user's
515 .Pa ~/.ssh/known_hosts
517 .Cm RhostsRSAAuthentication
519 .Cm HostbasedAuthentication .
522 .It Cm KerberosAuthentication
523 Specifies whether the password provided by the user for
524 .Cm PasswordAuthentication
525 will be validated through the Kerberos KDC.
526 To use this option, the server needs a
527 Kerberos servtab which allows the verification of the KDC's identity.
530 .It Cm KerberosGetAFSToken
531 If AFS is active and the user has a Kerberos 5 TGT, attempt to acquire
532 an AFS token before accessing the user's home directory.
535 .It Cm KerberosOrLocalPasswd
536 If password authentication through Kerberos fails then
537 the password will be validated via any additional local mechanism
542 .It Cm KerberosTicketCleanup
543 Specifies whether to automatically destroy the user's ticket cache
547 .It Cm KeyRegenerationInterval
548 In protocol version 1, the ephemeral server key is automatically regenerated
549 after this many seconds (if it has been used).
550 The purpose of regeneration is to prevent
551 decrypting captured sessions by later breaking into the machine and
553 The key is never stored anywhere.
554 If the value is 0, the key is never regenerated.
555 The default is 3600 (seconds).
557 Specifies the local addresses
560 The following forms may be used:
562 .Bl -item -offset indent -compact
566 .Ar host No | Ar IPv4_addr No | Ar IPv6_addr
571 .Ar host No | Ar IPv4_addr No : Ar port
577 .Ar host No | Ar IPv6_addr Oc : Ar port
584 sshd will listen on the address and all prior
587 The default is to listen on all local addresses.
590 options are permitted.
593 options must precede this option for non-port qualified addresses.
594 .It Cm LoginGraceTime
595 The server disconnects after this time if the user has not
596 successfully logged in.
597 If the value is 0, there is no time limit.
598 The default is 120 seconds.
600 Gives the verbosity level that is used when logging messages from
602 The possible values are:
603 QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.
605 DEBUG and DEBUG1 are equivalent.
606 DEBUG2 and DEBUG3 each specify higher levels of debugging output.
607 Logging with a DEBUG level violates the privacy of users and is not recommended.
609 Specifies the available MAC (message authentication code) algorithms.
610 The MAC algorithm is used in protocol version 2
611 for data integrity protection.
612 Multiple algorithms must be comma-separated.
614 .Bd -literal -offset indent
615 hmac-md5,hmac-sha1,umac-64@openssh.com,
616 hmac-ripemd160,hmac-sha1-96,hmac-md5-96
619 Introduces a conditional block.
620 If all of the criteria on the
622 line are satisfied, the keywords on the following lines override those
623 set in the global section of the config file, until either another
625 line or the end of the file.
629 are one or more criteria-pattern pairs.
630 The available criteria are
636 The match patterns may consist of single entries or comma-separated
637 lists and may use the wildcard and negation operators described in the
644 criteria may additionally contain addresses to match in CIDR
645 address/masklen format, e.g.\&
649 Note that the mask length provided must be consistent with the address -
650 it is an error to specify a mask length that is too long for the address
651 or one with bits set in this host portion of the address.
658 Only a subset of keywords may be used on the lines following a
661 Available keywords are
662 .Cm AllowAgentForwarding ,
663 .Cm AllowTcpForwarding ,
664 .Cm AuthorizedKeysFile ,
665 .Cm AuthorizedPrincipalsFile ,
667 .Cm ChrootDirectory ,
670 .Cm GSSAPIAuthentication ,
671 .Cm HostbasedAuthentication ,
672 .Cm HostbasedUsesNameFromPacketOnly ,
673 .Cm KbdInteractiveAuthentication ,
674 .Cm KerberosAuthentication ,
677 .Cm PasswordAuthentication ,
678 .Cm PermitEmptyPasswords ,
680 .Cm PermitRootLogin ,
682 .Cm PubkeyAuthentication ,
683 .Cm RhostsRSAAuthentication ,
684 .Cm RSAAuthentication ,
685 .Cm X11DisplayOffset ,
688 .Cm X11UseLocalHost .
690 Specifies the maximum number of authentication attempts permitted per
692 Once the number of failures reaches half this value,
693 additional failures are logged.
696 Specifies the maximum number of open sessions permitted per network connection.
699 Specifies the maximum number of concurrent unauthenticated connections to the
701 Additional connections will be dropped until authentication succeeds or the
703 expires for a connection.
706 Alternatively, random early drop can be enabled by specifying
707 the three colon separated values
711 will refuse connection attempts with a probability of
714 if there are currently
717 unauthenticated connections.
718 The probability increases linearly and all connection attempts
719 are refused if the number of unauthenticated connections reaches
722 .It Cm PasswordAuthentication
723 Specifies whether password authentication is allowed.
727 .Cm ChallengeResponseAuthentication
733 and the PAM authentication policy for
737 password authentication will be allowed through the challenge-response
738 mechanism regardless of the value of
739 .Cm PasswordAuthentication .
740 .It Cm PermitEmptyPasswords
741 When password authentication is allowed, it specifies whether the
742 server allows login to accounts with empty password strings.
746 Specifies the destinations to which TCP port forwarding is permitted.
747 The forwarding specification must be one of the following forms:
749 .Bl -item -offset indent -compact
763 .Ar \&[ IPv6_addr \&] : port
767 Multiple forwards may be specified by separating them with whitespace.
770 can be used to remove all restrictions and permit any forwarding requests.
771 By default all port forwarding requests are permitted.
772 .It Cm PermitRootLogin
773 Specifies whether root can log in using
777 .Dq without-password ,
778 .Dq forced-commands-only ,
784 .Cm ChallengeResponseAuthentication
787 the root user may be allowed in with its password even if
788 .Cm PermitRootLogin is set to
789 .Dq without-password .
791 If this option is set to
792 .Dq without-password ,
793 password authentication is disabled for root.
795 If this option is set to
796 .Dq forced-commands-only ,
797 root login with public key authentication will be allowed,
800 option has been specified
801 (which may be useful for taking remote backups even if root login is
802 normally not allowed).
803 All other authentication methods are disabled for root.
805 If this option is set to
807 root is not allowed to log in.
811 device forwarding is allowed.
827 .It Cm PermitUserEnvironment
829 .Pa ~/.ssh/environment
833 .Pa ~/.ssh/authorized_keys
838 Enabling environment processing may enable users to bypass access
839 restrictions in some configurations using mechanisms such as
842 Specifies the file that contains the process ID of the
845 .Pa /var/run/sshd.pid .
847 Specifies the port number that
851 Multiple options of this type are permitted.
857 should print the date and time of the last user login when a user logs
866 when a user logs in interactively.
867 (On some systems it is also printed by the shell,
873 Specifies the protocol versions
876 The possible values are
880 Multiple versions must be comma-separated.
883 Note that the order of the protocol list does not indicate preference,
884 because the client selects among multiple protocol versions offered
890 .It Cm PubkeyAuthentication
891 Specifies whether public key authentication is allowed.
894 Note that this option applies to protocol version 2 only.
896 Specifies a list of revoked public keys.
897 Keys listed in this file will be refused for public key authentication.
898 Note that if this file is not readable, then public key authentication will
899 be refused for all users.
900 .It Cm RhostsRSAAuthentication
901 Specifies whether rhosts or
903 authentication together
904 with successful RSA host authentication is allowed.
907 This option applies to protocol version 1 only.
908 .It Cm RSAAuthentication
909 Specifies whether pure RSA authentication is allowed.
912 This option applies to protocol version 1 only.
914 Defines the number of bits in the ephemeral protocol version 1 server key.
915 The minimum value is 512, and the default is 1024.
919 should check file modes and ownership of the
920 user's files and home directory before accepting login.
921 This is normally desirable because novices sometimes accidentally leave their
922 directory or files world-writable.
925 Note that this does not apply to
926 .Cm ChrootDirectory ,
927 whose permissions and ownership are checked unconditionally.
929 Configures an external subsystem (e.g. file transfer daemon).
930 Arguments should be a subsystem name and a command (with optional arguments)
931 to execute upon subsystem request.
937 file transfer subsystem.
941 implements an in-process
944 This may simplify configurations using
946 to force a different filesystem root on clients.
948 By default no subsystems are defined.
949 Note that this option applies to protocol version 2 only.
950 .It Cm SyslogFacility
951 Gives the facility code that is used when logging messages from
953 The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
954 LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
957 Specifies whether the system should send TCP keepalive messages to the
959 If they are sent, death of the connection or crash of one
960 of the machines will be properly noticed.
961 However, this means that
962 connections will die if the route is down temporarily, and some people
964 On the other hand, if TCP keepalives are not sent,
965 sessions may hang indefinitely on the server, leaving
967 users and consuming server resources.
971 (to send TCP keepalive messages), and the server will notice
972 if the network goes down or the client host crashes.
973 This avoids infinitely hanging sessions.
975 To disable TCP keepalive messages, the value should be set to
977 .It Cm TrustedUserCAKeys
978 Specifies a file containing public keys of certificate authorities that are
979 trusted to sign user certificates for authentication.
980 Keys are listed one per line; empty lines and comments starting with
983 If a certificate is presented for authentication and has its signing CA key
984 listed in this file, then it may be used for authentication for any user
985 listed in the certificate's principals list.
986 Note that certificates that lack a list of principals will not be permitted
987 for authentication using
988 .Cm TrustedUserCAKeys .
989 For more details on certificates, see the
996 should look up the remote host name and check that
997 the resolved host name for the remote IP address maps back to the
998 very same IP address.
1004 is used for interactive login sessions.
1009 is never used for remote command execution.
1010 Note also, that if this is enabled,
1012 will be disabled because
1014 does not know how to handle
1018 .Cm UsePrivilegeSeparation
1019 is specified, it will be disabled after authentication.
1021 Enables the Pluggable Authentication Module interface.
1024 this will enable PAM authentication using
1025 .Cm ChallengeResponseAuthentication
1027 .Cm PasswordAuthentication
1028 in addition to PAM account and session module processing for all
1029 authentication types.
1031 Because PAM challenge-response authentication usually serves an equivalent
1032 role to password authentication, you should disable either
1033 .Cm PasswordAuthentication
1035 .Cm ChallengeResponseAuthentication.
1039 is enabled, you will not be able to run
1044 .It Cm UsePrivilegeSeparation
1047 separates privileges by creating an unprivileged child process
1048 to deal with incoming network traffic.
1049 After successful authentication, another process will be created that has
1050 the privilege of the authenticated user.
1051 The goal of privilege separation is to prevent privilege
1052 escalation by containing any corruption within the unprivileged processes.
1055 .It Cm VersionAddendum
1056 Specifies a string to append to the regular version string to identify
1057 OS- or site-specific modifications.
1059 .Dq DragonFly-20090620 .
1060 .It Cm X11DisplayOffset
1061 Specifies the first display number available for
1064 This prevents sshd from interfering with real X11 servers.
1066 .It Cm X11Forwarding
1067 Specifies whether X11 forwarding is permitted.
1068 The argument must be
1075 When X11 forwarding is enabled, there may be additional exposure to
1076 the server and to client displays if the
1078 proxy display is configured to listen on the wildcard address (see
1080 below), though this is not the default.
1081 Additionally, the authentication spoofing and authentication data
1082 verification and substitution occur on the client side.
1083 The security risk of using X11 forwarding is that the client's X11
1084 display server may be exposed to attack when the SSH client requests
1085 forwarding (see the warnings for
1088 .Xr ssh_config 5 ) .
1089 A system administrator may have a stance in which they want to
1090 protect clients that may expose themselves to attack by unwittingly
1091 requesting X11 forwarding, which can warrant a
1095 Note that disabling X11 forwarding does not prevent users from
1096 forwarding X11 traffic, as users can always install their own forwarders.
1097 X11 forwarding is automatically disabled if
1100 .It Cm X11UseLocalhost
1103 should bind the X11 forwarding server to the loopback address or to
1104 the wildcard address.
1106 sshd binds the forwarding server to the loopback address and sets the
1107 hostname part of the
1109 environment variable to
1111 This prevents remote hosts from connecting to the proxy display.
1112 However, some older X11 clients may not function with this
1117 to specify that the forwarding server should be bound to the wildcard
1119 The argument must be
1125 .It Cm XAuthLocation
1126 Specifies the full pathname of the
1130 .Pa /usr/X11R6/bin/xauth .
1134 command-line arguments and configuration file options that specify time
1135 may be expressed using a sequence of the form:
1137 .Ar time Op Ar qualifier ,
1141 is a positive integer value and
1143 is one of the following:
1145 .Bl -tag -width Ds -compact -offset indent
1160 Each member of the sequence is added together to calculate
1161 the total time value.
1163 Time format examples:
1165 .Bl -tag -width Ds -compact -offset indent
1167 600 seconds (10 minutes)
1171 1 hour 30 minutes (90 minutes)
1175 .It Pa /etc/ssh/sshd_config
1176 Contains configuration data for
1178 This file should be writable by root only, but it is recommended
1179 (though not necessary) that it be world-readable.
1184 OpenSSH is a derivative of the original and free
1185 ssh 1.2.12 release by Tatu Ylonen.
1186 Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1187 Theo de Raadt and Dug Song
1188 removed many bugs, re-added newer features and
1190 Markus Friedl contributed the support for SSH
1191 protocol versions 1.5 and 2.0.
1192 Niels Provos and Markus Friedl contributed support
1193 for privilege separation.