hostname.if —
interface-specific configuration files
TABLE OF CONTENTS
The hostname.* files contain information regarding the
configuration of each network interface. One file should exist for each
interface that is to be configured, such as
hostname.fxp0 or
hostname.bridge0. A configuration file is not needed
for lo0.
The configuration information is expressed in a line-by-line
packed format which makes the most common cases simpler; those dense formats
are described below. Any lines not matching these packed formats are passed
directly to ifconfig(8). The packed
formats are converted using a somewhat inflexible parser and the
administrator should not expect magic — if in doubt study
ifconfig(8) and the per-driver manual
pages to see what arguments are permitted.
Arguments containing either whitespace or single quote characters
must be double quoted. For example:
inet 10.0.0.1 255.255.255.0 10.0.0.255 description "Bob's uplink"
Each line is processed separately and in order. For example:
nwid mynwid wpakey mywpakey
inet6 autoconf
dhcp
would run ifconfig to set the nwid and wpakey of the interface,
run it again to set the AUTOCONF6 flag, and then start
dhclient(8).
The following packed formats are valid for configuring network interfaces with
static addresses:
Regular IPv4 network setup:
inet
[alias] addr
netmask broadcast_addr
options
dest dest_addr
Regular IPv6 network setup:
inet6
[alias] addr
prefixlen options
dest dest_addr
Other network setup:
addr_family
options
A typical file contains only one line, but more extensive files
are possible, for example:
media 100baseTX description Uplink
inet 10.0.1.12 255.255.255.0 10.0.1.255
inet alias 10.0.1.13 255.255.255.255 10.0.1.13
inet alias 10.0.1.14 255.255.255.255 NONE
inet alias 10.0.1.15 255.255.255.255
inet alias 10.0.1.16 0xffffffff
# This is an example comment line.
inet6 alias fec0::1 64
inet6 alias fec0::2 64 anycast
!route add 65.65.65.65 10.0.1.13
up
The above formats have the following field values:
- addr_family
- The address family of the interface, generally “inet” or
“inet6”.
alias- The literal string “alias” if this is an additional network
address for the interface.
- addr
- The optional address that belongs to the interface, such as 190.191.192.1
or fe80:2::1. It is also feasible to use a hostname as specified in
/etc/hosts. It is recommended that an address be
used instead of symbolic information, since the latter might activate
resolver(3) library routines.
If no address is specified, the netmask,
broadcast_addr, dest, and
dest_addr options are invalid and will be
ignored.
- netmask
- The optional network mask for the interface, e.g., 255.255.255.0. If
addr is specified but netmask
is not, the classful mask based on addr is
used.
- broadcast_addr
- The optional broadcast address for the interface, e.g., 190.191.192.255.
The word “NONE” can also be specified in order to configure
the broadcast address based on the netmask. The
netmask option must be present in order to use this
option.
- options
- Miscellaneous options to set on the interface, e.g., “media
100baseTX mediaopt full-duplex”. Valid options for a particular
interface type can be found in
ifconfig(8). When used, the
netmask and broadcast_addr
options must also be present.
dest- If the interface needs a destination address set, this is the literal text
“dest”. As shown in the example, this declaration should
start on a separate line.
- dest_addr
- The destination address to be set on the interface, such as 190.191.192.2.
It is also feasible to use a hostname as specified in
/etc/hosts. It is recommended that an address be
used instead of symbolic information which might activate
resolver(3) library routines.
- prefixlen
- The prefixlen number, or number of bits in the netmask, to be set on the
interface, such as 64.
#- Comments are allowed. Anything following a comment character is treated as
a comment.
!command- Arbitrary shell commands can be executed using this directive, as long as
they are available in the single-user environment (for instance,
/bin or /sbin). Useful for
doing interface-specific configuration such as setting up custom routes
using route(8) or establishing tunnels
using ifconfig(8). It is worth noting
that “\$if” in a command line will be replaced by the
interface name.
The following packed formats are valid for configuring network interfaces with
dynamic addresses:
A DHCP-configured network interface setup consists of
dhcp
options
The above format has the following field values:
dhcp- The literal string “dhcp” if the interface is to be
configured using DHCP. See
dhclient(8) and
dhclient.conf(5) for more
details.
- options
- Miscellaneous options to set on the interface, e.g., “media
100baseTX mediaopt full-duplex”. Valid options for a particular
interface type can be found in
ifconfig(8).
IPv6 stateless address autoconfiguration:
inet6 autoconf
options
The above format has the following field values:
inet6- The address family.
autoconf- The literal string “autoconf”, to configure the interface
using IPv6 stateless address autoconfiguration (SLAAC).
- options
- Miscellaneous options to set on the interface, e.g., “media
100baseTX mediaopt full-duplex”. Valid options for a particular
interface type can be found in
ifconfig(8).
If the network interface is a bridge, the options described in the bridge
section of the ifconfig(8) manual page
apply.
For example:
add fxp0
add ep1
-learn fxp0
#
!ipsecctl -F
#
static fxp0 8:0:20:1e:2f:2b
up # and finally enable it
- /etc/hostname.XXX
- Interface-specific configuration files.