.\"	$NetBSD: ifconfig.if.5,v 1.18.8.1 2020/04/23 13:59:32 martin Exp $
.\"
.\" Copyright (c) 1996 Matthew R. Green
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.Dd April 15, 2020
.Dt IFCONFIG.IF 5
.Os
.Sh NAME
.Nm ifconfig.if
.Nd interface-specific configuration files or variables
.Sh DESCRIPTION
The
.Nm
files or variables contain information regarding the configuration
of each network interface.
.Nm
is processed by
.Pa /etc/rc.d/network
at system boot time.
.Pp
For each interface
.Pq Ar nnX
that is to be configured, there should be either an
.Sy ifconfig_nnX
variable in
.Xr rc.conf 5 ,
or an
.Pa /etc/ifconfig.nnX
file
(such as the
.Sy ifconfig_fxp0
variable or the
.Pa /etc/ifconfig.fxp0
file for the
.Sy fxp0
interface).
Only characters allowed in
.Xr sh 1
variables names should be used for
.Ar nnX
.Po Xr ascii 7
uppercase and lowercase letters, digits, and underscore
.Pc .
.Pp
The variable or file will get evaluated only if the interface exists on
the system.
Multiple lines can be placed in a variable or file, and will be
evaluated sequentially.
In the case of a variable, semicolons may be used instead of
newlines, as described in
.Xr rc.conf 5 .
.Ao backslash Ac Ns Ao newline Ac
sequences in files are ignored, so long logical lines may be
made up of several shorter physical lines.
.Pp
Normally, a line will be evaluated as command line arguments to
.Xr ifconfig 8 .
.Dq Li ifconfig Ar nnX
will be prepended on evaluation.
Arguments with embedded shell metacharacters should be quoted in
.Xr sh 1
style.
.Pp
If the line is equal to
.Dq dhcp ,
.Xr dhcpcd 8
will be started for the interface.
However, it is instead recommended that
.Sy dhcpcd
is set to true in
.Xr rc.conf 5
and any per interface configuration or restriction is done in
.Xr dhcpcd.conf 5 .
.Pp
If the line is equal to
.Dq rtsol ,
kernel processing of router advertisements will be enabled and an IPv6
router solicitation message will be sent out on the interface.
This is useful on networks where default routes can best be learned
from router advertisements.
However, if
.Sy dhcpcd
has been set to true in
.Xr rc.conf 5 ,
it is assumed that
.Xr dhcpcd 8
will take care of sending any necessary router solicitation messages and
processing received router advertisements through its configuration in
.Xr dhcpcd.conf 5
instead.
.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 but may not be modified.
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 2001:db8::1 prefixlen 64 alias
# have subnet router anycast address too
inet6 2001:db8:: prefixlen 64 alias anycast
.Ed
.Pp
For networks that do not use a virtual address for the default gateway
that could be set using a single address in
.Sy defaultroute6 ,
static IPv6 address configuration could use the
.Dq rtsol
keyword instead to solicit router advertisements for learning a default
route and even achieving route redundancy given multiple responding
routers:
.Bd -literal -offset indent
inet6 2001:db8::100 prefixlen 64 alias
rtsol
.Ed
.Pp
The following example sets a network name for a wireless interface
(using quotes to protect special characters in the name),
and starts
.Xr dhcpcd 8 :
.Bd -literal -offset indent
ssid 'my network'
dhcp
.Ed
.Pp
The following example is for dynamically-created pseudo interfaces like
.Xr gif 4 .
Earlier versions of
.Pa /etc/rc.d/network
required an explicit
.Sq create
command for such interfaces,
but creation is now handled automatically.
.Bd -literal -offset indent
up
# configure IPv6 default route toward the interface
!route add -inet6 default ::1
!route change -inet6 default -ifp $int
.Ed
.Sh FILES
.Pa /etc/rc.d/network
.Sh SEE ALSO
.Xr rc.conf 5 ,
.Xr ifconfig 8