- jmc@cvs.openbsd.org 2006/02/24 23:43:57
[sshd_config.5]
some grammar/wording fixes;
diff --git a/sshd_config.5 b/sshd_config.5
index 642e1fa..6f60d7e 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -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 1.51 2006/02/24 20:31:31 jmc Exp $
+.\" $OpenBSD: sshd_config.5,v 1.52 2006/02/24 23:43:57 jmc Exp $
.Dd September 25, 1999
.Dt SSHD_CONFIG 5
.Os
@@ -89,7 +89,7 @@
Valid arguments are
.Dq any ,
.Dq inet
-(use IPv4 only) or
+(use IPv4 only), or
.Dq inet6
(use IPv6 only).
The default is
@@ -135,9 +135,9 @@
for user authentication.
.Cm AuthorizedKeysFile
may contain tokens of the form %T which are substituted during connection
-set-up.
+setup.
The following tokens are defined: %% is replaced by a literal '%',
-%h is replaced by the home directory of the user being authenticated and
+%h is replaced by the home directory of the user being authenticated, and
%u is replaced by the username of that user.
After expansion,
.Cm AuthorizedKeysFile
@@ -176,20 +176,19 @@
.Dq blowfish-cbc ,
and
.Dq cast128-cbc .
-The default is
-.Bd -literal
- ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,
- arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr,
- aes192-ctr,aes256-ctr''
+The default is:
+.Bd -literal -offset 3n
+aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,
+arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr,
+aes192-ctr,aes256-ctr
.Ed
.It Cm ClientAliveCountMax
Sets the number of client alive messages (see below) which may be
sent without
-.Nm sshd
+.Xr sshd 8
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.
+sshd will disconnect the client, terminating the session.
It is important to note that the use of client alive messages is very
different from
.Cm TCPKeepAlive
@@ -207,12 +206,12 @@
.Cm ClientAliveInterval
(see below) is set to 15, and
.Cm ClientAliveCountMax
-is left at the default, unresponsive ssh clients
+is left at the default, unresponsive SSH clients
will be disconnected after approximately 45 seconds.
.It Cm ClientAliveInterval
Sets a timeout interval in seconds after which if no data has been received
from the client,
-.Nm sshd
+.Xr sshd 8
will send a message through the encrypted
channel to request a response from the client.
The default
@@ -260,12 +259,11 @@
Specifies whether remote hosts are allowed to connect to ports
forwarded for the client.
By default,
-.Nm sshd
+.Xr sshd 8
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
+can be used to specify that sshd
should allow remote port forwardings to bind to non-loopback addresses, thus
allowing other hosts to connect.
The argument may be
@@ -308,7 +306,7 @@
.Pa /etc/ssh/ssh_host_dsa_key
for protocol version 2.
Note that
-.Nm sshd
+.Xr sshd 8
will refuse to use a file if it is group/world-accessible.
It is possible to have multiple host key files.
.Dq rsa1
@@ -335,7 +333,7 @@
.Dq yes .
.It Cm IgnoreUserKnownHosts
Specifies whether
-.Nm sshd
+.Xr sshd 8
should ignore the user's
.Pa ~/.ssh/known_hosts
during
@@ -350,24 +348,24 @@
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
+The default is
.Dq no .
.It Cm KerberosGetAFSToken
If AFS is active and the user has a Kerberos 5 TGT, attempt to acquire
an AFS token before accessing the user's home directory.
-Default is
+The default is
.Dq no .
.It Cm KerberosOrLocalPasswd
-If set then if password authentication through Kerberos fails then
+If password authentication through Kerberos fails then
the password will be validated via any additional local mechanism
such as
.Pa /etc/passwd .
-Default is
+The default is
.Dq yes .
.It Cm KerberosTicketCleanup
Specifies whether to automatically destroy the user's ticket cache
file on logout.
-Default is
+The default is
.Dq yes .
.It Cm KeyRegenerationInterval
In protocol version 1, the ephemeral server key is automatically regenerated
@@ -380,7 +378,7 @@
The default is 3600 (seconds).
.It Cm ListenAddress
Specifies the local addresses
-.Nm sshd
+.Xr sshd 8
should listen on.
The following forms may be used:
.Pp
@@ -406,8 +404,7 @@
If
.Ar port
is not specified,
-.Nm sshd
-will listen on the address and all prior
+sshd will listen on the address and all prior
.Cm Port
options specified.
The default is to listen on all local addresses.
@@ -416,7 +413,7 @@
options are permitted.
Additionally, any
.Cm Port
-options must precede this option for non port qualified addresses.
+options must precede this option for non-port qualified addresses.
.It Cm LoginGraceTime
The server disconnects after this time if the user has not
successfully logged in.
@@ -426,7 +423,7 @@
Gives the verbosity level that is used when logging messages from
.Nm sshd .
The possible values are:
-QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3.
+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.
@@ -436,7 +433,7 @@
The MAC algorithm is used in protocol version 2
for data integrity protection.
Multiple algorithms must be comma-separated.
-The default is
+The default is:
.Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
.It Cm MaxAuthTries
Specifies the maximum number of authentication attempts permitted per
@@ -446,8 +443,7 @@
The default is 6.
.It Cm MaxStartups
Specifies the maximum number of concurrent unauthenticated connections to the
-.Nm sshd
-daemon.
+SSH daemon.
Additional connections will be dropped until authentication succeeds or the
.Cm LoginGraceTime
expires for a connection.
@@ -484,18 +480,18 @@
The argument must be
.Dq yes ,
.Dq without-password ,
-.Dq forced-commands-only
+.Dq forced-commands-only ,
or
.Dq no .
The default is
.Dq yes .
.Pp
If this option is set to
-.Dq without-password
+.Dq without-password ,
password authentication is disabled for root.
.Pp
If this option is set to
-.Dq forced-commands-only
+.Dq forced-commands-only ,
root login with public key authentication will be allowed,
but only if the
.Ar command
@@ -505,7 +501,7 @@
All other authentication methods are disabled for root.
.Pp
If this option is set to
-.Dq no
+.Dq no ,
root is not allowed to log in.
.It Cm PermitTunnel
Specifies whether
@@ -514,7 +510,7 @@
The argument must be
.Dq yes ,
.Dq point-to-point ,
-.Dq ethernet
+.Dq ethernet ,
or
.Dq no .
The default is
@@ -527,7 +523,7 @@
options in
.Pa ~/.ssh/authorized_keys
are processed by
-.Nm sshd .
+.Xr sshd 8 .
The default is
.Dq no .
Enabling environment processing may enable users to bypass access
@@ -541,7 +537,7 @@
.Pa /var/run/sshd.pid .
.It Cm Port
Specifies the port number that
-.Nm sshd
+.Xr sshd 8
listens on.
The default is 22.
Multiple options of this type are permitted.
@@ -549,14 +545,14 @@
.Cm ListenAddress .
.It Cm PrintLastLog
Specifies whether
-.Nm sshd
+.Xr sshd 8
should print the date and time of the last user login when a user logs
in interactively.
The default is
.Dq yes .
.It Cm PrintMotd
Specifies whether
-.Nm sshd
+.Xr sshd 8
should print
.Pa /etc/motd
when a user logs in interactively.
@@ -567,12 +563,12 @@
.Dq yes .
.It Cm Protocol
Specifies the protocol versions
-.Nm sshd
+.Xr sshd 8
supports.
The possible values are
-.Dq 1
+.Sq 1
and
-.Dq 2 .
+.Sq 2 .
Multiple versions must be comma-separated.
The default is
.Dq 2,1 .
@@ -604,7 +600,7 @@
The minimum value is 512, and the default is 768.
.It Cm StrictModes
Specifies whether
-.Nm sshd
+.Xr sshd 8
should check file modes and ownership of the
user's files and home directory before accepting login.
This is normally desirable because novices sometimes accidentally leave their
@@ -651,7 +647,7 @@
.Dq no .
.It Cm UseDNS
Specifies whether
-.Nm sshd
+.Xr sshd 8
should look up the remote host name and check that
the resolved host name for the remote IP address maps back to the
very same IP address.
@@ -702,7 +698,7 @@
.Dq no .
.It Cm UsePrivilegeSeparation
Specifies whether
-.Nm sshd
+.Xr sshd 8
separates privileges by creating an unprivileged child process
to deal with incoming network traffic.
After successful authentication, another process will be created that has
@@ -713,11 +709,9 @@
.Dq yes .
.It Cm X11DisplayOffset
Specifies the first display number available for
-.Nm sshd Ns 's
+.Xr sshd 8 Ns 's
X11 forwarding.
-This prevents
-.Nm sshd
-from interfering with real X11 servers.
+This prevents sshd from interfering with real X11 servers.
The default is 10.
.It Cm X11Forwarding
Specifies whether X11 forwarding is permitted.
@@ -730,14 +724,14 @@
.Pp
When X11 forwarding is enabled, there may be additional exposure to
the server and to client displays if the
-.Nm sshd
+.Xr sshd 8
proxy display is configured to listen on the wildcard address (see
.Cm X11UseLocalhost
-below), however this is not the default.
+below), though this is not the default.
Additionally, the authentication spoofing and authentication data
verification and substitution occur on the client side.
The security risk of using X11 forwarding is that the client's X11
-display server may be exposed to attack when the ssh client requests
+display server may be exposed to attack when the SSH client requests
forwarding (see the warnings for
.Cm ForwardX11
in
@@ -755,12 +749,11 @@
is enabled.
.It Cm X11UseLocalhost
Specifies whether
-.Nm sshd
+.Xr sshd 8
should bind the X11 forwarding server to the loopback address or to
the wildcard address.
By default,
-.Nm sshd
-binds the forwarding server to the loopback address and sets the
+sshd binds the forwarding server to the loopback address and sets the
hostname part of the
.Ev DISPLAY
environment variable to