interfaces(5)
NAME
interfaces - network interface configuration for ifupdown
DESCRIPTION
By default, ifupdown2.conf sets /etc/network/interfaces as the
network interface configuration file. This file contains
information for the ifup(8), ifdown(8) and ifquery(8) commands.
This is where you configure how your system is connected to the
network.
Lines starting with # are ignored. Note that end-of-line comments
are NOT supported, comments must be on a line of their own.
A line may be extended across multiple lines by making the last
character a backslash.
The file consists of zero or more "iface", "auto", "allow-" and
"source" stanzas. Here is an example:
auto lo eth0
allow-hotplug eth1
iface lo inet loopback
source /etc/network/interfaces.d/bridges
iface eth0 inet static
address 192.168.1.1/24
up flush-mail
iface eth1 inet dhcp
Lines beginning with the word "auto" are used to identify the
physical interfaces to be brought up when ifup is run with the -a
option. (This option is used by the system boot scripts.) Physical
interface names should follow the word "auto" on the same line.
There can be multiple "auto" stanzas.
Lines beginning with "allow-" are used to identify interfaces
that should be brought up automatically by various subsystems.
This may be done using a command such as "ifup --allow=hotplug eth0
eth1", which will only bring up eth0 or eth1 if it is listed in
an "allow-hotplug" line. Note that "allow-auto" and "auto" are
synonyms.
Lines beginning with "source" are used to include stanzas from
other files, so configuration can be split into many files. The word
"source" is followed by the path of file to be sourced. Shell
wildcards can be used. Currently only supports absolute path
names.
iface is normally given a interface name as its first non-option
argument.
The interface name is followed by the name of the address family
that the interface uses. This will be "inet" for TCP/IP networking
and inet6 for ipv6. Following that is the name of the method used to
configure the interface.
ifupdown supports iface stanzas without a family or a method. This
enables using the same stanza for inet and inet6 family addresses.
And the method defaults to "static"
Additional interface options/attributes can be given on subsequent
lines in the iface stanza. These options come from addon modules.
see ifupdown-addons-interfaces(5) for these options.
example bridge interface with additional attributes listed in the
ifupdown-addons-interfaces(5) man page:
auto br0
iface br0
address 12.0.0.4/24
address 2000:1000:1000:1000:3::5/128
bridge-ports swp1 swp2 swp3
bridge-stp on
ifupdown supports python-mako style templates in the interfaces
file. See examples section for details.
See /usr/share/doc/python-ifupdown2/examples/ for interfaces(5) file
examples and interfaces file generation scripts.
METHODS
Both inet and inet6 address family interfaces can use the following
methods (However they are not required):
The loopback Method
This method may be used to define the loopback interface.
The static Method
This method may be used to define ethernet interfaces with
statically allocated addresses.
The dhcp Method
This method may be used to obtain an address via DHCP.
BUILTIN INTERFACES
iface sections for some interfaces like physical interfaces or vlan
interfaces in dot notation (like eth1.100) are understood by
ifupdown. These interfaces do not need an entry in the interfaces
file if they are dependents of other interfaces and don't need any
specific configurations like addresses etc.
EXAMPLES
Sample /etc/network/interfaces file:
auto lo
iface lo
address 192.168.2.0/24
address 2001:dee:eeee:1::4/128
auto eth0
iface eth0 inet dhcp
auto eth1
iface eth1 inet manual
address 192.168.2.0/24
address 2001:dee:eeee:1::4/128
# source files from a directory /etc/network/interfaces.d
source /etc/network/interfaces.d/*
# Using mako style templates
% for v in [11,12]:
auto vlan${v}
iface vlan${v} inet static
address 10.20.${v}.3/24
% endfor
For additional syntax and examples see ifupdown-addons-interfaces(5)
FILES
configuration file defined in ifupdown2.conf (default
/etc/network/interfaces)
SEE ALSO
ifupdown-addons-interfaces(5), ifup(8), ifquery(8), ifreload(8)
AUTHOR
Roopa Prabhu <roopa@cumulusnetworks.com>
COPYRIGHT
Copyright 2014 Cumulus Networks, Inc. All rights reserved.
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