.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" As far as I am concerned, the code I have written for this software
.\" can be used freely for any purpose. Any derived versions of this
.\" software must be clearly marked as such, and if the derived work is
.\" incompatible with the protocol description in the RFC file, it must be
.\" called by a name other than "ssh" or "Secure Shell".
.\"
.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
.\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
.\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (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 1.157 2012/06/29 13:57:25 naddy Exp $
.Dd $Mdocdate: June 29 2012 $
.Dt SSH_CONFIG 5
.Os
.Sh NAME
.Nm ssh_config
.Nd OpenSSH SSH client configuration files
.Sh SYNOPSIS
.Nm ~/.ssh/config
.Nm /etc/ssh/ssh_config
.Sh DESCRIPTION
.Xr ssh 1
obtains configuration data from the following sources in
the following order:
.Pp
.Bl -enum -offset indent -compact
.It
command-line options
.It
user's configuration file
.Pq Pa ~/.ssh/config
.It
system-wide configuration file
.Pq Pa /etc/ssh/ssh_config
.El
.Pp
For each parameter, the first obtained value
will be used.
The configuration files contain sections separated by
.Dq Host
specifications, and that section is only applied for hosts that
match one of the patterns given in the specification.
The matched host name is the one given on the command line.
.Pp
Since the first obtained value for each parameter is used, more
host-specific declarations should be given near the beginning of the
file, and general defaults at the end.
.Pp
The configuration file has the following format:
.Pp
Empty lines and lines starting with
.Ql #
are comments.
Otherwise a line is of the format
.Dq keyword arguments .
Configuration options may be separated by whitespace or
optional whitespace and exactly one
.Ql = ;
the latter format is useful to avoid the need to quote whitespace
when specifying configuration options using the
.Nm ssh ,
.Nm scp ,
and
.Nm sftp
.Fl o
option.
Arguments may optionally be enclosed in double quotes
.Pq \&"
in order to represent arguments containing spaces.
.Pp
The possible
keywords and their meanings are as follows (note that
keywords are case-insensitive and arguments are case-sensitive):
.Bl -tag -width Ds
.It Cm Host
Restricts the following declarations (up to the next
.Cm Host
keyword) to be only for those hosts that match one of the patterns
given after the keyword.
If more than one pattern is provided, they should be separated by whitespace.
A single
.Ql *
as a pattern can be used to provide global
defaults for all hosts.
The host is the
.Ar hostname
argument given on the command line (i.e. the name is not converted to
a canonicalized host name before matching).
.Pp
A pattern entry may be negated by prefixing it with an exclamation mark
.Pq Sq !\& .
If a negated entry is matched, then the
.Cm Host
entry is ignored, regardless of whether any other patterns on the line
match.
Negated matches are therefore useful to provide exceptions for wildcard
matches.
.Pp
See
.Sx PATTERNS
for more information on patterns.
.It Cm AddressFamily
Specifies which address family to use when connecting.
Valid arguments are
.Dq any ,
.Dq inet
(use IPv4 only), or
.Dq inet6
(use IPv6 only).
.It Cm BatchMode
If set to
.Dq yes ,
passphrase/password querying will be disabled.
This option is useful in scripts and other batch jobs where no user
is present to supply the password.
The argument must be
.Dq yes
or
.Dq no .
The default is
.Dq no .
.It Cm BindAddress
Use the specified address on the local machine as the source address of
the connection.
Only useful on systems with more than one address.
Note that this option does not work if
.Cm UsePrivilegedPort
is set