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authorColin Watson <cjwatson@debian.org>2003-09-23 18:08:35 +0000
committerColin Watson <cjwatson@debian.org>2003-09-23 18:08:35 +0000
commitd59fd3e421aa81b8e5e118f3f806081df2aca879 (patch)
tree356a4e607edc979c625bb33db63c656d771478bd /sshd_config.5
parent7505658c58e96b8d270f1928a0e1fa7f3e0c266b (diff)
parent45431c9b4677608680cd071768cbf156b316a7e8 (diff)
Merge 3.7.1p2 to the trunk. I have absolutely no idea yet whether this will
work.
Diffstat (limited to 'sshd_config.5')
-rw-r--r--sshd_config.5115
1 files changed, 58 insertions, 57 deletions
diff --git a/sshd_config.5 b/sshd_config.5
index 6f38a260a..727fdb12a 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -34,7 +34,7 @@
34.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 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. 35.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36.\" 36.\"
37.\" $OpenBSD: sshd_config.5,v 1.15 2003/03/28 10:11:43 jmc Exp $ 37.\" $OpenBSD: sshd_config.5,v 1.25 2003/09/01 09:50:04 markus Exp $
38.Dd September 25, 1999 38.Dd September 25, 1999
39.Dt SSHD_CONFIG 5 39.Dt SSHD_CONFIG 5
40.Os 40.Os
@@ -61,10 +61,6 @@ The possible
61keywords and their meanings are as follows (note that 61keywords and their meanings are as follows (note that
62keywords are case-insensitive and arguments are case-sensitive): 62keywords are case-insensitive and arguments are case-sensitive):
63.Bl -tag -width Ds 63.Bl -tag -width Ds
64.It Cm AFSTokenPassing
65Specifies whether an AFS token may be forwarded to the server.
66Default is
67.Dq no .
68.It Cm AllowGroups 64.It Cm AllowGroups
69This keyword can be followed by a list of group name patterns, separated 65This keyword can be followed by a list of group name patterns, separated
70by spaces. 66by spaces.
@@ -72,7 +68,7 @@ If specified, login is allowed only for users whose primary
72group or supplementary group list matches one of the patterns. 68group or supplementary group list matches one of the patterns.
73.Ql \&* 69.Ql \&*
74and 70and
75.Ql ? 71.Ql \&?
76can be used as 72can be used as
77wildcards in the patterns. 73wildcards in the patterns.
78Only group names are valid; a numerical group ID is not recognized. 74Only group names are valid; a numerical group ID is not recognized.
@@ -93,7 +89,7 @@ If specified, login is allowed only for user names that
93match one of the patterns. 89match one of the patterns.
94.Ql \&* 90.Ql \&*
95and 91and
96.Ql ? 92.Ql \&?
97can be used as 93can be used as
98wildcards in the patterns. 94wildcards in the patterns.
99Only user names are valid; a numerical user ID is not recognized. 95Only user names are valid; a numerical user ID is not recognized.
@@ -107,7 +103,8 @@ Specifies the file that contains the public keys that can be used
107for user authentication. 103for user authentication.
108.Cm AuthorizedKeysFile 104.Cm AuthorizedKeysFile
109may contain tokens of the form %T which are substituted during connection 105may contain tokens of the form %T which are substituted during connection
110set-up. The following tokens are defined: %% is replaced by a literal '%', 106set-up.
107The following tokens are defined: %% is replaced by a literal '%',
111%h is replaced by the home directory of the user being authenticated and 108%h is replaced by the home directory of the user being authenticated and
112%u is replaced by the username of that user. 109%u is replaced by the username of that user.
113After expansion, 110After expansion,
@@ -138,7 +135,7 @@ The default is
138.Pp 135.Pp
139.Bd -literal 136.Bd -literal
140 ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour, 137 ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
141 aes192-cbc,aes256-cbc'' 138 aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr''
142.Ed 139.Ed
143.It Cm ClientAliveInterval 140.It Cm ClientAliveInterval
144Sets a timeout interval in seconds after which if no data has been received 141Sets a timeout interval in seconds after which if no data has been received
@@ -153,20 +150,24 @@ This option applies to protocol version 2 only.
153Sets the number of client alive messages (see above) which may be 150Sets the number of client alive messages (see above) which may be
154sent without 151sent without
155.Nm sshd 152.Nm sshd
156receiving any messages back from the client. If this threshold is 153receiving any messages back from the client.
157reached while client alive messages are being sent, 154If this threshold is reached while client alive messages are being sent,
158.Nm sshd 155.Nm sshd
159will disconnect the client, terminating the session. It is important 156will disconnect the client, terminating the session.
160to note that the use of client alive messages is very different from 157It is important to note that the use of client alive messages is very
158different from
161.Cm KeepAlive 159.Cm KeepAlive
162(below). The client alive messages are sent through the 160(below).
163encrypted channel and therefore will not be spoofable. The TCP keepalive 161The client alive messages are sent through the encrypted channel
164option enabled by 162and therefore will not be spoofable.
163The TCP keepalive option enabled by
165.Cm KeepAlive 164.Cm KeepAlive
166is spoofable. The client alive mechanism is valuable when the client or 165is spoofable.
166The client alive mechanism is valuable when the client or
167server depend on knowing when a connection has become inactive. 167server depend on knowing when a connection has become inactive.
168.Pp 168.Pp
169The default value is 3. If 169The default value is 3.
170If
170.Cm ClientAliveInterval 171.Cm ClientAliveInterval
171(above) is set to 15, and 172(above) is set to 15, and
172.Cm ClientAliveCountMax 173.Cm ClientAliveCountMax
@@ -187,7 +188,7 @@ Login is disallowed for users whose primary group or supplementary
187group list matches one of the patterns. 188group list matches one of the patterns.
188.Ql \&* 189.Ql \&*
189and 190and
190.Ql ? 191.Ql \&?
191can be used as 192can be used as
192wildcards in the patterns. 193wildcards in the patterns.
193Only group names are valid; a numerical group ID is not recognized. 194Only group names are valid; a numerical group ID is not recognized.
@@ -199,7 +200,7 @@ by spaces.
199Login is disallowed for user names that match one of the patterns. 200Login is disallowed for user names that match one of the patterns.
200.Ql \&* 201.Ql \&*
201and 202and
202.Ql ? 203.Ql \&?
203can be used as wildcards in the patterns. 204can be used as wildcards in the patterns.
204Only user names are valid; a numerical user ID is not recognized. 205Only user names are valid; a numerical user ID is not recognized.
205By default, login is allowed for all users. 206By default, login is allowed for all users.
@@ -224,6 +225,17 @@ or
224.Dq no . 225.Dq no .
225The default is 226The default is
226.Dq no . 227.Dq no .
228.It Cm GSSAPIAuthentication
229Specifies whether user authentication based on GSSAPI is allowed.
230The default is
231.Dq no .
232Note that this option applies to protocol version 2 only.
233.It Cm GSSAPICleanupCredentials
234Specifies whether to automatically destroy the user's credentials cache
235on logout.
236The default is
237.Dq yes .
238Note that this option applies to protocol version 2 only.
227.It Cm HostbasedAuthentication 239.It Cm HostbasedAuthentication
228Specifies whether rhosts or /etc/hosts.equiv authentication together 240Specifies whether rhosts or /etc/hosts.equiv authentication together
229with successful public key client host authentication is allowed 241with successful public key client host authentication is allowed
@@ -259,7 +271,6 @@ Specifies that
259and 271and
260.Pa .shosts 272.Pa .shosts
261files will not be used in 273files will not be used in
262.Cm RhostsAuthentication ,
263.Cm RhostsRSAAuthentication 274.Cm RhostsRSAAuthentication
264or 275or
265.Cm HostbasedAuthentication . 276.Cm HostbasedAuthentication .
@@ -303,11 +314,9 @@ This avoids infinitely hanging sessions.
303To disable keepalives, the value should be set to 314To disable keepalives, the value should be set to
304.Dq no . 315.Dq no .
305.It Cm KerberosAuthentication 316.It Cm KerberosAuthentication
306Specifies whether Kerberos authentication is allowed. 317Specifies whether the password provided by the user for
307This can be in the form of a Kerberos ticket, or if
308.Cm PasswordAuthentication 318.Cm PasswordAuthentication
309is yes, the password provided by the user will be validated through 319will be validated through the Kerberos KDC.
310the Kerberos KDC.
311To use this option, the server needs a 320To use this option, the server needs a
312Kerberos servtab which allows the verification of the KDC's identity. 321Kerberos servtab which allows the verification of the KDC's identity.
313Default is 322Default is
@@ -319,11 +328,6 @@ such as
319.Pa /etc/passwd . 328.Pa /etc/passwd .
320Default is 329Default is
321.Dq yes . 330.Dq yes .
322.It Cm KerberosTgtPassing
323Specifies whether a Kerberos TGT may be forwarded to the server.
324Default is
325.Dq no ,
326as this only works when the Kerberos KDC is actually an AFS kaserver.
327.It Cm KerberosTicketCleanup 331.It Cm KerberosTicketCleanup
328Specifies whether to automatically destroy the user's ticket cache 332Specifies whether to automatically destroy the user's ticket cache
329file on logout. 333file on logout.
@@ -369,11 +373,12 @@ is not specified,
369.Nm sshd 373.Nm sshd
370will listen on the address and all prior 374will listen on the address and all prior
371.Cm Port 375.Cm Port
372options specified. The default is to listen on all local 376options specified.
373addresses. 377The default is to listen on all local addresses.
374Multiple 378Multiple
375.Cm ListenAddress 379.Cm ListenAddress
376options are permitted. Additionally, any 380options are permitted.
381Additionally, any
377.Cm Port 382.Cm Port
378options must precede this option for non port qualified addresses. 383options must precede this option for non port qualified addresses.
379.It Cm LoginGraceTime 384.It Cm LoginGraceTime
@@ -422,12 +427,6 @@ The probability increases linearly and all connection attempts
422are refused if the number of unauthenticated connections reaches 427are refused if the number of unauthenticated connections reaches
423.Dq full 428.Dq full
424(60). 429(60).
425.It Cm PAMAuthenticationViaKbdInt
426Specifies whether PAM challenge response authentication is allowed. This
427allows the use of most PAM challenge response authentication modules, but
428it will allow password authentication regardless of whether
429.Cm PasswordAuthentication
430is enabled.
431.It Cm PasswordAuthentication 430.It Cm PasswordAuthentication
432Specifies whether password authentication is allowed. 431Specifies whether password authentication is allowed.
433The default is 432The default is
@@ -460,8 +459,8 @@ but only if the
460.Ar command 459.Ar command
461option has been specified 460option has been specified
462(which may be useful for taking remote backups even if root login is 461(which may be useful for taking remote backups even if root login is
463normally not allowed). All other authentication methods are disabled 462normally not allowed).
464for root. 463All other authentication methods are disabled for root.
465.Pp 464.Pp
466If this option is set to 465If this option is set to
467.Dq no 466.Dq no
@@ -534,10 +533,6 @@ Specifies whether public key authentication is allowed.
534The default is 533The default is
535.Dq yes . 534.Dq yes .
536Note that this option applies to protocol version 2 only. 535Note that this option applies to protocol version 2 only.
537.It Cm RhostsAuthentication
538Specifies whether authentication using rhosts or /etc/hosts.equiv
539files is sufficient.
540Normally, this method should not be permitted because it is insecure.
541.Cm RhostsRSAAuthentication 536.Cm RhostsRSAAuthentication
542should be used 537should be used
543instead, because it performs RSA-based host authentication in addition 538instead, because it performs RSA-based host authentication in addition
@@ -585,6 +580,14 @@ Gives the facility code that is used when logging messages from
585The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, 580The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
586LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. 581LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
587The default is AUTH. 582The default is AUTH.
583.It Cm UseDNS
584Specifies whether
585.Nm sshd
586should lookup the remote host name and check that
587the resolved host name for the remote IP address maps back to the
588very same IP address.
589The default is
590.Dq yes .
588.It Cm UseLogin 591.It Cm UseLogin
589Specifies whether 592Specifies whether
590.Xr login 1 593.Xr login 1
@@ -604,6 +607,13 @@ cookies.
604If 607If
605.Cm UsePrivilegeSeparation 608.Cm UsePrivilegeSeparation
606is specified, it will be disabled after authentication. 609is specified, it will be disabled after authentication.
610.It Cm UsePAM
611Enables PAM authentication (via challenge-response) and session set up.
612If you enable this, you should probably disable
613.Cm PasswordAuthentication .
614If you enable
615.CM UsePAM
616then you will not be able to run sshd as a non-root user.
607.It Cm UsePrivilegeSeparation 617.It Cm UsePrivilegeSeparation
608Specifies whether 618Specifies whether
609.Nm sshd 619.Nm sshd
@@ -615,14 +625,6 @@ The goal of privilege separation is to prevent privilege
615escalation by containing any corruption within the unprivileged processes. 625escalation by containing any corruption within the unprivileged processes.
616The default is 626The default is
617.Dq yes . 627.Dq yes .
618.It Cm VerifyReverseMapping
619Specifies whether
620.Nm sshd
621should try to verify the remote host name and check that
622the resolved host name for the remote IP address maps back to the
623very same IP address.
624The default is
625.Dq no .
626.It Cm X11DisplayOffset 628.It Cm X11DisplayOffset
627Specifies the first display number available for 629Specifies the first display number available for
628.Nm sshd Ns 's 630.Nm sshd Ns 's
@@ -653,7 +655,7 @@ display server may be exposed to attack when the ssh client requests
653forwarding (see the warnings for 655forwarding (see the warnings for
654.Cm ForwardX11 656.Cm ForwardX11
655in 657in
656.Xr ssh_config 5 ). 658.Xr ssh_config 5 ) .
657A system administrator may have a stance in which they want to 659A system administrator may have a stance in which they want to
658protect clients that may expose themselves to attack by unwittingly 660protect clients that may expose themselves to attack by unwittingly
659requesting X11 forwarding, which can warrant a 661requesting X11 forwarding, which can warrant a
@@ -699,7 +701,6 @@ The default is
699.Pa /usr/X11R6/bin/xauth . 701.Pa /usr/X11R6/bin/xauth .
700.El 702.El
701.Ss Time Formats 703.Ss Time Formats
702.Pp
703.Nm sshd 704.Nm sshd
704command-line arguments and configuration file options that specify time 705command-line arguments and configuration file options that specify time
705may be expressed using a sequence of the form: 706may be expressed using a sequence of the form:
@@ -748,6 +749,8 @@ Contains configuration data for
748This file should be writable by root only, but it is recommended 749This file should be writable by root only, but it is recommended
749(though not necessary) that it be world-readable. 750(though not necessary) that it be world-readable.
750.El 751.El
752.Sh SEE ALSO
753.Xr sshd 8
751.Sh AUTHORS 754.Sh AUTHORS
752OpenSSH is a derivative of the original and free 755OpenSSH is a derivative of the original and free
753ssh 1.2.12 release by Tatu Ylonen. 756ssh 1.2.12 release by Tatu Ylonen.
@@ -759,5 +762,3 @@ Markus Friedl contributed the support for SSH
759protocol versions 1.5 and 2.0. 762protocol versions 1.5 and 2.0.
760Niels Provos and Markus Friedl contributed support 763Niels Provos and Markus Friedl contributed support
761for privilege separation. 764for privilege separation.
762.Sh SEE ALSO
763.Xr sshd 8