=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/sshd_config.5,v retrieving revision 1.13.2.3 retrieving revision 1.14 diff -u -r1.13.2.3 -r1.14 --- src/usr.bin/ssh/sshd_config.5 2003/09/16 21:20:29 1.13.2.3 +++ src/usr.bin/ssh/sshd_config.5 2003/01/23 08:58:47 1.14 @@ -34,7 +34,7 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: sshd_config.5,v 1.13.2.3 2003/09/16 21:20:29 brad Exp $ +.\" $OpenBSD: sshd_config.5,v 1.14 2003/01/23 08:58:47 jmc Exp $ .Dd September 25, 1999 .Dt SSHD_CONFIG 5 .Os @@ -61,6 +61,10 @@ keywords and their meanings are as follows (note that keywords are case-insensitive and arguments are case-sensitive): .Bl -tag -width Ds +.It Cm AFSTokenPassing +Specifies whether an AFS token may be forwarded to the server. +Default is +.Dq no . .It Cm AllowGroups This keyword can be followed by a list of group name patterns, separated by spaces. @@ -68,7 +72,7 @@ group or supplementary group list matches one of the patterns. .Ql \&* and -.Ql \&? +.Ql ? can be used as wildcards in the patterns. Only group names are valid; a numerical group ID is not recognized. @@ -89,7 +93,7 @@ match one of the patterns. .Ql \&* and -.Ql \&? +.Ql ? can be used as wildcards in the patterns. Only user names are valid; a numerical user ID is not recognized. @@ -103,8 +107,7 @@ for user authentication. .Cm AuthorizedKeysFile may contain tokens of the form %T which are substituted during connection -set-up. -The following tokens are defined: %% is replaced by a literal '%', +set-up. The following tokens are defined: %% is replaced by a literal '%', %h is replaced by the home directory of the user being authenticated and %u is replaced by the username of that user. After expansion, @@ -135,7 +138,7 @@ .Pp .Bd -literal ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour, - aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr'' + aes192-cbc,aes256-cbc'' .Ed .It Cm ClientAliveInterval Sets a timeout interval in seconds after which if no data has been received @@ -150,24 +153,20 @@ Sets the number of client alive messages (see above) which may be sent without .Nm sshd -receiving any messages back from the client. -If this threshold is reached while client alive messages are being sent, +receiving any messages back from the client. If this threshold is +reached while client alive messages are being sent, .Nm sshd -will disconnect the client, terminating the session. -It is important to note that the use of client alive messages is very -different from +will disconnect the client, terminating the session. It is important +to note that the use of client alive messages is very different from .Cm KeepAlive -(below). -The client alive messages are sent through the encrypted channel -and therefore will not be spoofable. -The TCP keepalive option enabled by +(below). The client alive messages are sent through the +encrypted channel and therefore will not be spoofable. The TCP keepalive +option enabled by .Cm KeepAlive -is spoofable. -The client alive mechanism is valuable when the client or +is spoofable. The client alive mechanism is valuable when the client or server depend on knowing when a connection has become inactive. .Pp -The default value is 3. -If +The default value is 3. If .Cm ClientAliveInterval (above) is set to 15, and .Cm ClientAliveCountMax @@ -188,7 +187,7 @@ group list matches one of the patterns. .Ql \&* and -.Ql \&? +.Ql ? can be used as wildcards in the patterns. Only group names are valid; a numerical group ID is not recognized. @@ -200,7 +199,7 @@ Login is disallowed for user names that match one of the patterns. .Ql \&* and -.Ql \&? +.Ql ? can be used as wildcards in the patterns. Only user names are valid; a numerical user ID is not recognized. By default, login is allowed for all users. @@ -212,8 +211,8 @@ forwarded for the client. By default, .Nm sshd -binds remote port forwardings to the loopback address. -This prevents other remote hosts from connecting to forwarded ports. +binds remote port forwardings to the loopback address. This +prevents other remote hosts from connecting to forwarded ports. .Cm GatewayPorts can be used to specify that .Nm sshd @@ -225,17 +224,6 @@ .Dq no . The default is .Dq no . -.It Cm GSSAPIAuthentication -Specifies whether user authentication based on GSSAPI is allowed. -The default is -.Dq no . -Note that this option applies to protocol version 2 only. -.It Cm GSSAPICleanupCredentials -Specifies whether to automatically destroy the user's credentials cache -on logout. -The default is -.Dq yes . -Note that this option applies to protocol version 2 only. .It Cm HostbasedAuthentication Specifies whether rhosts or /etc/hosts.equiv authentication together with successful public key client host authentication is allowed @@ -271,6 +259,7 @@ and .Pa .shosts files will not be used in +.Cm RhostsAuthentication , .Cm RhostsRSAAuthentication or .Cm HostbasedAuthentication . @@ -314,9 +303,11 @@ To disable keepalives, the value should be set to .Dq no . .It Cm KerberosAuthentication -Specifies whether the password provided by the user for +Specifies whether Kerberos authentication is allowed. +This can be in the form of a Kerberos ticket, or if .Cm PasswordAuthentication -will be validated through the Kerberos KDC. +is yes, the password provided by the user will be validated through +the Kerberos KDC. To use this option, the server needs a Kerberos servtab which allows the verification of the KDC's identity. Default is @@ -328,6 +319,11 @@ .Pa /etc/passwd . Default is .Dq yes . +.It Cm KerberosTgtPassing +Specifies whether a Kerberos TGT may be forwarded to the server. +Default is +.Dq no , +as this only works when the Kerberos KDC is actually an AFS kaserver. .It Cm KerberosTicketCleanup Specifies whether to automatically destroy the user's ticket cache file on logout. @@ -373,12 +369,10 @@ .Nm sshd will listen on the address and all prior .Cm Port -options specified. -The default is to listen on all local addresses. -Multiple +options specified. The default is to listen on all local +addresses. Multiple .Cm ListenAddress -options are permitted. -Additionally, any +options are permitted. Additionally, any .Cm Port options must precede this option for non port qualified addresses. .It Cm LoginGraceTime @@ -391,10 +385,10 @@ .Nm sshd . The possible values are: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3. -The default is INFO. -DEBUG and DEBUG1 are equivalent. -DEBUG2 and DEBUG3 each specify higher levels of debugging output. -Logging with a DEBUG level violates the privacy of users and is not recommended. +The default is INFO. DEBUG and DEBUG1 are equivalent. DEBUG2 +and DEBUG3 each specify higher levels of debugging output. +Logging with a DEBUG level violates the privacy of users +and is not recommended. .It Cm MACs Specifies the available MAC (message authentication code) algorithms. The MAC algorithm is used in protocol version 2 @@ -459,8 +453,8 @@ .Ar command option has been specified (which may be useful for taking remote backups even if root login is -normally not allowed). -All other authentication methods are disabled for root. +normally not allowed). All other authentication methods are disabled +for root. .Pp If this option is set to .Dq no @@ -533,6 +527,10 @@ The default is .Dq yes . Note that this option applies to protocol version 2 only. +.It Cm RhostsAuthentication +Specifies whether authentication using rhosts or /etc/hosts.equiv +files is sufficient. +Normally, this method should not be permitted because it is insecure. .Cm RhostsRSAAuthentication should be used instead, because it performs RSA-based host authentication in addition @@ -580,14 +578,6 @@ The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH. -.It Cm UseDNS -Specifies whether -.Nm sshd -should lookup the remote host name and check that -the resolved host name for the remote IP address maps back to the -very same IP address. -The default is -.Dq yes . .It Cm UseLogin Specifies whether .Xr login 1 @@ -603,21 +593,27 @@ .Xr login 1 does not know how to handle .Xr xauth 1 -cookies. -If +cookies. If .Cm UsePrivilegeSeparation is specified, it will be disabled after authentication. .It Cm UsePrivilegeSeparation Specifies whether .Nm sshd separates privileges by creating an unprivileged child process -to deal with incoming network traffic. -After successful authentication, another process will be created that has -the privilege of the authenticated user. -The goal of privilege separation is to prevent privilege +to deal with incoming network traffic. After successful authentication, +another process will be created that has the privilege of the authenticated +user. The goal of privilege separation is to prevent privilege escalation by containing any corruption within the unprivileged processes. The default is .Dq yes . +.It Cm VerifyReverseMapping +Specifies whether +.Nm sshd +should try to verify the remote host name and check that +the resolved host name for the remote IP address maps back to the +very same IP address. +The default is +.Dq no . .It Cm X11DisplayOffset Specifies the first display number available for .Nm sshd Ns 's @@ -648,7 +644,7 @@ forwarding (see the warnings for .Cm ForwardX11 in -.Xr ssh_config 5 ) . +.Xr ssh_config 5 ). A system administrator may have a stance in which they want to protect clients that may expose themselves to attack by unwittingly requesting X11 forwarding, which can warrant a @@ -664,8 +660,7 @@ Specifies whether .Nm sshd should bind the X11 forwarding server to the loopback address or to -the wildcard address. -By default, +the wildcard address. By default, .Nm sshd binds the forwarding server to the loopback address and sets the hostname part of the @@ -694,6 +689,7 @@ .Pa /usr/X11R6/bin/xauth . .El .Ss Time Formats +.Pp .Nm sshd command-line arguments and configuration file options that specify time may be expressed using a sequence of the form: @@ -742,8 +738,6 @@ This file should be writable by root only, but it is recommended (though not necessary) that it be world-readable. .El -.Sh SEE ALSO -.Xr sshd 8 .Sh AUTHORS OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. @@ -755,3 +749,5 @@ protocol versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support for privilege separation. +.Sh SEE ALSO +.Xr sshd 8