Provided by: ifupdown2_1.0~git20170314-1_all bug


       interfaces - network interface configuration for ifupdown


          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
                  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 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.


          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

          The dhcp Method
                 This method may be used to obtain an address via DHCP.


          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.


          Sample /etc/network/interfaces file:

              auto lo
              iface lo
                  address 2001:dee:eeee:1::4/128

              auto eth0
              iface eth0 inet dhcp

              auto eth1
              iface eth1 inet manual
                  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)


          configuration file defined in ifupdown2.conf (default /etc/network/interfaces)


          ifupdown-addons-interfaces(5), ifup(8), ifquery(8), ifreload(8)


       Roopa Prabhu <>


       Copyright 2014 Cumulus Networks, Inc.  All rights reserved.