Provided by: ifupdown2_1.0~git20151029-1_all bug


       interfaces - network interface configuration for ifupdown


          /etc/network/interfaces  contains  network  interface configuration 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 subsytems. 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)




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


       Roopa Prabhu <>


       Copyright 2014 Cumulus Networks, Inc.  All rights reserved.