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.