===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/ssh_config.5,v
retrieving revision 1.20
retrieving revision 1.20.2.2
diff -u -r1.20 -r1.20.2.2
--- src/usr.bin/ssh/ssh_config.5	2003/09/02 18:50:06	1.20
+++ src/usr.bin/ssh/ssh_config.5	2004/08/19 22:37:32	1.20.2.2
@@ -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: ssh_config.5,v 1.20 2003/09/02 18:50:06 jmc Exp $
+.\" $OpenBSD: ssh_config.5,v 1.20.2.2 2004/08/19 22:37:32 brad Exp $
 .Dd September 25, 1999
 .Dt SSH_CONFIG 5
 .Os
@@ -185,8 +185,19 @@
 Specifies the ciphers allowed for protocol version 2
 in order of preference.
 Multiple ciphers must be comma-separated.
+The supported ciphers are
+.Dq 3des-cbc ,
+.Dq aes128-cbc ,
+.Dq aes192-cbc ,
+.Dq aes256-cbc ,
+.Dq aes128-ctr ,
+.Dq aes192-ctr ,
+.Dq aes256-ctr ,
+.Dq arcfour ,
+.Dq blowfish-cbc ,
+and
+.Dq cast128-cbc .
 The default is
-.Pp
 .Bd -literal
   ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
     aes192-cbc,aes256-cbc''
@@ -233,6 +244,37 @@
 server, instead of using the default system TCP timeout.
 This value is used only when the target is down or really unreachable,
 not when it refuses the connection.
+.It Cm ControlMaster
+Enables the sharing of multiple sessions over a single network connection.
+When set to
+.Dq yes
+.Nm ssh
+will listen for connections on a control socket specified using the
+.Cm ControlPath
+argument.
+Additional sessions can connect to this socket using the same
+.Cm ControlPath
+with
+.Cm ControlMaster
+set to
+.Dq no
+(the default).
+These sessions will reuse the master instance's network connection rather
+than initiating new ones.
+Setting this to
+.Dq ask
+will cause
+.Nm ssh
+to listen for control connections, but require confirmation using the
+.Ev SSH_ASKPASS
+program before they are accepted (see
+.Xr ssh-add 1
+for details).
+.It Cm ControlPath
+Specify the path to the control socket used for connection sharing.
+See
+.Cm ControlMaster
+above.
 .It Cm DynamicForward
 Specifies that a TCP/IP port on the local machine be forwarded
 over the secure channel, and the application
@@ -260,6 +302,7 @@
 .Dq no .
 The default is
 .Dq no .
+This option should be placed in the non-hostspecific section.
 See
 .Xr ssh-keysign 8
 for more information.
@@ -306,9 +349,27 @@
 .Pp
 X11 forwarding should be enabled with caution.
 Users with the ability to bypass file permissions on the remote host
-(for the user's X authorization database)
+(for the user's X11 authorization database)
 can access the local X11 display through the forwarded connection.
-An attacker may then be able to perform activities such as keystroke monitoring.
+An attacker may then be able to perform activities such as keystroke monitoring
+if the
+.Cm ForwardX11Trusted
+option is also enabled.
+.It Cm ForwardX11Trusted
+If this option is set to
+.Dq yes
+then remote X11 clients will have full access to the original X11 display.
+If this option is set to
+.Dq no
+then remote X11 clients will be considered untrusted and prevented
+from stealing or tampering with data belonging to trusted X11
+clients.
+.Pp
+The default is
+.Dq no .
+.Pp
+See the X11 SECURITY extension specification for full details on
+the restrictions imposed on untrusted clients.
 .It Cm GatewayPorts
 Specifies whether remote hosts are allowed to connect to local
 forwarded ports.
@@ -332,11 +393,9 @@
 host key database instead of
 .Pa /etc/ssh/ssh_known_hosts .
 .It Cm GSSAPIAuthentication
-Specifies whether authentication based on GSSAPI may be used, either using
-the result of a successful key exchange, or using GSSAPI user
-authentication.
+Specifies whether user authentication based on GSSAPI is allowed.
 The default is
-.Dq yes .
+.Dq no .
 Note that this option applies to protocol version 2 only.
 .It Cm GSSAPIDelegateCredentials
 Forward (delegate) credentials to the server.
@@ -390,23 +449,24 @@
 It is possible to have
 multiple identity files specified in configuration files; all these
 identities will be tried in sequence.
-.It Cm KeepAlive
-Specifies whether the system should send TCP keepalive messages to the
-other side.
-If they are sent, death of the connection or crash of one
-of the machines will be properly noticed.
-However, this means that
-connections will die if the route is down temporarily, and some people
-find it annoying.
-.Pp
-The default is
+.It Cm IdentitiesOnly
+Specifies that
+.Nm ssh
+should only use the authentication identity files configured in the
+.Nm
+files,
+even if the
+.Nm ssh-agent
+offers more identities.
+The argument to this keyword must be
 .Dq yes
-(to send keepalives), and the client will notice
-if the network goes down or the remote host dies.
-This is important in scripts, and many users want it too.
-.Pp
-To disable keepalives, the value should be set to
+or
 .Dq no .
+This option is intented for situations where
+.Nm ssh-agent
+offers many different identities.
+The default is
+.Dq no .
 .It Cm LocalForward
 Specifies that a TCP/IP port on the local machine be forwarded over
 the secure channel to the specified host and port from the remote machine.
@@ -553,6 +613,63 @@
 The default is
 .Dq yes .
 Note that this option applies to protocol version 1 only.
+.It Cm SendEnv
+Specifies what variables from the local
+.Xr environ 7
+should be sent to the server.
+Note that environment passing is only supported for protocol 2, the
+server must also support it, and the server must be configured to
+accept these environment variables.
+Refer to
+.Cm AcceptEnv
+in
+.Xr sshd_config 5
+for how to configure the server.
+Variables are specified by name, which may contain the wildcard characters
+.Ql \&*
+and
+.Ql \&? .
+Multiple environment variables may be separated by whitespace or spread
+across multiple
+.Cm SendEnv
+directives.
+The default is not to send any environment variables.
+.It Cm ServerAliveInterval
+Sets a timeout interval in seconds after which if no data has been received
+from the server,
+.Nm ssh
+will send a message through the encrypted
+channel to request a response from the server.
+The default
+is 0, indicating that these messages will not be sent to the server.
+This option applies to protocol version 2 only.
+.It Cm ServerAliveCountMax
+Sets the number of server alive messages (see above) which may be
+sent without
+.Nm ssh
+receiving any messages back from the server.
+If this threshold is reached while server alive messages are being sent,
+.Nm ssh
+will disconnect from the server, terminating the session.
+It is important to note that the use of server alive messages is very
+different from
+.Cm TCPKeepAlive
+(below).
+The server alive messages are sent through the encrypted channel
+and therefore will not be spoofable.
+The TCP keepalive option enabled by
+.Cm TCPKeepAlive
+is spoofable.
+The server 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, for example,
+.Cm ServerAliveInterval
+(above) is set to 15, and
+.Cm ServerAliveCountMax
+is left at the default, if the server becomes unresponsive ssh
+will disconnect after approximately 45 seconds.
 .It Cm SmartcardDevice
 Specifies which smartcard device to use.
 The argument to this keyword is the device
@@ -595,6 +712,23 @@
 .Dq ask .
 The default is
 .Dq ask .
+.It Cm TCPKeepAlive
+Specifies whether the system should send TCP keepalive messages to the
+other side.
+If they are sent, death of the connection or crash of one
+of the machines will be properly noticed.
+However, this means that
+connections will die if the route is down temporarily, and some people
+find it annoying.
+.Pp
+The default is
+.Dq yes
+(to send TCP keepalive messages), and the client will notice
+if the network goes down or the remote host dies.
+This is important in scripts, and many users want it too.
+.Pp
+To disable TCP keepalive messages, the value should be set to
+.Dq no .
 .It Cm UsePrivilegedPort
 Specifies whether to use a privileged port for outgoing connections.
 The argument must be
@@ -624,6 +758,23 @@
 .It Cm VerifyHostKeyDNS
 Specifies whether to verify the remote key using DNS and SSHFP resource
 records.
+If this option is set to
+.Dq yes ,
+the client will implicitly trust keys that match a secure fingerprint
+from DNS.
+Insecure fingerprints will be handled as if this option was set to
+.Dq ask .
+If this option is set to
+.Dq ask ,
+information on fingerprint match will be displayed, but the user will still
+need to confirm new host keys according to the
+.Cm StrictHostKeyChecking
+option.
+The argument must be
+.Dq yes ,
+.Dq no
+or
+.Dq ask .
 The default is
 .Dq no .
 Note that this option applies to protocol version 2 only.
@@ -642,9 +793,8 @@
 This file is used by the
 .Nm ssh
 client.
-This file does not usually contain any sensitive information,
-but the recommended permissions are read/write for the user, and not
-accessible by others.
+Because of the potential for abuse, this file must have strict permissions:
+read/write for the user, and not accessible by others.
 .It Pa /etc/ssh/ssh_config
 Systemwide configuration file.
 This file provides defaults for those