- djm@cvs.openbsd.org 2010/01/30 02:54:53

[openssh.git] / sshd.8

diff --git a/sshd.8 b/sshd.8
index 419394329838e0b43dae326962e49c7e190e188a..8563e021ccada93d4641ee49c589816468fa8d16 100644 (file)
--- a/sshd.8
+++ b/sshd.8
@@ -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.
 .\"
 .\" (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 1.237 2007/06/07 19:37:34 pvalchev Exp $
+.\" $OpenBSD: sshd.8,v 1.249 2009/10/08 20:42:13 jmc Exp $

 .Dd $Mdocdate$
 .Dt SSHD 8
 .Os
 .Dd $Mdocdate$
 .Dt SSHD 8
 .Os


@@ -44,8 +44,9 @@
 .Sh SYNOPSIS
 .Nm sshd
 .Bk -words
 .Sh SYNOPSIS
 .Nm sshd
 .Bk -words

-.Op Fl 46Ddeiqt
+.Op Fl 46DdeiqTt

 .Op Fl b Ar bits
 .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
 .Op Fl f Ar config_file
 .Op Fl g Ar login_grace_time
 .Op Fl h Ar host_key_file


@@ -99,7 +100,25 @@ Forces
 to use IPv6 addresses only.
 .It Fl b Ar bits
 Specifies the number of bits in the ephemeral protocol version 1
 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
 .It Fl D
 When this option is specified,
 .Nm


@@ -191,6 +210,15 @@ Quiet mode.
 Nothing is sent to the system log.
 Normally the beginning,
 authentication, and termination of each connection is logged.
 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.
 .It Fl t
 Test mode.
 Only check the validity of the configuration file and sanity of the keys.


@@ -232,7 +260,7 @@ or
 .El
 .Sh AUTHENTICATION
 The OpenSSH SSH daemon supports SSH protocols 1 and 2.
 .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
 though this can be changed via the
 .Cm Protocol
 option in


@@ -503,23 +531,27 @@ This option is automatically disabled if
 .Cm UseLogin
 is enabled.
 .It Cm from="pattern-list"
 .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.
 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.
 .It Cm no-agent-forwarding
 Forbids authentication agent forwarding when this key is used for
 authentication.


@@ -531,6 +563,9 @@ This might be used, e.g. in connection with the
 option.
 .It Cm no-pty
 Prevents tty allocation (a request to allocate a pty will fail).
 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.
 .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.


@@ -682,6 +717,13 @@ This file is used in exactly the same way as
 but allows host-based authentication without permitting login with
 rlogin/rsh.
 .Pp
 but allows host-based authentication without permitting login with
 rlogin/rsh.
 .Pp

+.It ~/.ssh/
+This directory is the default location for all user-specific configuration
+and authentication information.
+There is no general requirement to keep the entire contents of this directory
+secret, but the recommended permissions are read/write/execute for the user,
+and not accessible by others.
+.Pp

 .It ~/.ssh/authorized_keys
 Lists the public keys (RSA/DSA) that can be used for logging in as this user.
 The format of this file is described above.
 .It ~/.ssh/authorized_keys
 Lists the public keys (RSA/DSA) that can be used for logging in as this user.
 The format of this file is described above.


@@ -699,8 +741,6 @@ will not allow it to be used unless the
 .Cm StrictModes
 option has been set to
 .Dq no .
 .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).
 .Pp
 .It ~/.ssh/environment
 This file is read into the environment at login (if it exists).