.\" (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.8,v 1.239 2008/02/11 07:58:28 jmc Exp $
+.\" $OpenBSD: sshd.8,v 1.249 2009/10/08 20:42:13 jmc Exp $
.Dd $Mdocdate$
.Dt SSHD 8
.Os
.Sh SYNOPSIS
.Nm sshd
.Bk -words
-.Op Fl 46Ddeiqt
+.Op Fl 46DdeiqTt
.Op Fl b Ar bits
+.Op Fl C Ar connection_spec
.Op Fl f Ar config_file
.Op Fl g Ar login_grace_time
.Op Fl h Ar host_key_file
to use IPv6 addresses only.
.It Fl b Ar bits
Specifies the number of bits in the ephemeral protocol version 1
-server key (default 768).
+server key (default 1024).
+.It Fl C Ar connection_spec
+Specify the connection parameters to use for the
+.Fl T
+extended test mode.
+If provided, any
+.Cm Match
+directives in the configuration file
+that would apply to the specified user, host, and address will be set before
+the configuration is written to standard output.
+The connection parameters are supplied as keyword=value pairs.
+The keywords are
+.Dq user ,
+.Dq host ,
+and
+.Dq addr .
+All are required and may be supplied in any order, either with multiple
+.Fl C
+options or as a comma-separated list.
.It Fl D
When this option is specified,
.Nm
Nothing is sent to the system log.
Normally the beginning,
authentication, and termination of each connection is logged.
+.It Fl T
+Extended test mode.
+Check the validity of the configuration file, output the effective configuration
+to stdout and then exit.
+Optionally,
+.Cm Match
+rules may be applied by specifying the connection parameters using one or more
+.Fl C
+options.
.It Fl t
Test mode.
Only check the validity of the configuration file and sanity of the keys.
.El
.Sh AUTHENTICATION
The OpenSSH SSH daemon supports SSH protocols 1 and 2.
-Both protocols are supported by default,
+The default is to use protocol 2 only,
though this can be changed via the
.Cm Protocol
option in
.Cm UseLogin
is enabled.
.It Cm from="pattern-list"
-Specifies that in addition to public key authentication, the canonical name
-of the remote host must be present in the comma-separated list of
-patterns.
-The purpose
-of this option is to optionally increase security: public key authentication
-by itself does not trust the network or name servers or anything (but
-the key); however, if somebody somehow steals the key, the key
-permits an intruder to log in from anywhere in the world.
-This additional option makes using a stolen key more difficult (name
-servers and/or routers would have to be compromised in addition to
-just the key).
-.Pp
+Specifies that in addition to public key authentication, either the canonical
+name of the remote host or its IP address must be present in the
+comma-separated list of patterns.
See
.Sx PATTERNS
in
.Xr ssh_config 5
for more information on patterns.
+.Pp
+In addition to the wildcard matching that may be applied to hostnames or
+addresses, a
+.Cm from
+stanza may match IP addresses using CIDR address/masklen notation.
+.Pp
+The purpose of this option is to optionally increase security: public key
+authentication by itself does not trust the network or name servers or
+anything (but the key); however, if somebody somehow steals the key, the key
+permits an intruder to log in from anywhere in the world.
+This additional option makes using a stolen key more difficult (name
+servers and/or routers would have to be compromised in addition to
+just the key).
.It Cm no-agent-forwarding
Forbids authentication agent forwarding when this key is used for
authentication.
option.
.It Cm no-pty
Prevents tty allocation (a request to allocate a pty will fail).
+.It Cm no-user-rc
+Disables execution of
+.Pa ~/.ssh/rc .
.It Cm no-X11-forwarding
Forbids X11 forwarding when this key is used for authentication.
Any X11 forward requests by the client will return an error.
.Cm StrictModes
option has been set to
.Dq no .
-The recommended permissions can be set by executing
-.Dq chmod go-w ~/ ~/.ssh ~/.ssh/authorized_keys .
.Pp
.It ~/.ssh/environment
This file is read into the environment at login (if it exists).