.\"	$NetBSD: ifconfig.if.5,v 1.7 2002/10/13 00:46:59 wiz Exp $
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.\" Copyright (c) 1996 Matthew R. Green
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.Dd October 5, 2002
.Dt IFCONFIG.IF 5
.Os
.Sh NAME
.Nm ifconfig.if
.Nd interface-specific configuration files
.Sh DESCRIPTION
The
.Nm
files contain information regarding the configuration of each network interface.
.Nm
is processed by
.Pa /etc/rc.d/network
at system boot time.
.Pp
One file should exist for each interface that is to be configured, such as
.Pa /etc/ifconfig.fxp0 .
The file will get evaluated only if the interface exists on the system.
Multiple lines can be placed in a file, and will be evaluated sequentially.
.Pp
Normally, a line will be evaluated as command line arguments to
.Xr ifconfig 8 .
.Dq Li ifconfig if
will be prepended on evaluation.
.Pp
If a line is empty, or starts with
.Sq # ,
the line will be ignored as comment.
.Pp
If a line starts with
.Sq \&! ,
the rest of line will get evaluated as shell script fragment.
Shell variables declared in
.Pa /etc/rc.d/network
are accessible.
The most useful variable is
.Li $int ,
as it will be bound to the interface being configured with the file.
.Pp
For example, the following illustrates static interface configuration:
.Bd -literal -offset indent
# IPv4, with an alias
inet 10.0.1.12 netmask 255.255.255.0 media 100baseTX
inet 10.0.1.13 netmask 255.255.255.255 alias
# let us have IPv6 address on this interface
inet6 fec0::1 prefixlen 64 alias
# have subnet router anycast address too
inet6 fec0:: prefixlen 64 alias anycast
.Ed
.Pp
The following illustrates dynamic configuration setup with
.Xr dhclient 8
and
.Xr rtsol 8 :
.Bd -literal -offset indent
up
# autoconfigure IPv4 address
!dhclient $int
# autoconfigure IPv6 address.  Be sure to set $ip6mode to autohost.
!rtsol $int
.Ed
.Pp
The following example is for dynamically-created pseudo interfaces like
.Xr gif 4 :
.Bd -literal -offset indent
up
# configure IPv6 default route toward the interface
!route add -inet6 default ::1
!route change -inet6 default -ifp $int
.Ed
.Pp
Earlier versions of
.Pa /etc/rc.d/network
required an explicit
.Sq create
command for such interfaces.
This is now handled automatically.
.Sh FILES
.Pa /etc/rc.d/network
.Sh SEE ALSO
.Xr rc.conf 5 ,
.Xr ifconfig 8