Provided by: ifupdown_0.6.8ubuntu21_i386 bug

NAME

       /etc/network/interfaces  - network interface configuration for ifup and
       ifdown

DESCRIPTION

       /etc/network/interfaces  contains   network   interface   configuration
       information  for the ifup(8) and ifdown(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",  "mapping",  "auto"  and
       "allow-" stanzas. Here is an example.

              auto lo eth0
              allow-hotplug eth1

              iface lo inet loopback

              mapping eth0
                   script /usr/local/sbin/map-scheme
                   map HOME eth0-home
                   map WORK eth0-work

              iface eth0-home inet static
                   address 192.168.1.1
                   netmask 255.255.255.0
                   up flush-mail

              iface eth0-work inet dhcp

              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.   ifup  brings  the  named  interfaces up in the order
       listed.

       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.

       Stanzas beginning with the word "mapping" are used to determine  how  a
       logical interface name is chosen for a physical interface that is to be
       brought up.  The first line of a mapping stanza consists  of  the  word
       "mapping"  followed  by  a  pattern in shell glob syntax.  Each mapping
       stanza must contain a script definition.  The named script is run  with
       the  physical  interface  name as its argument and with the contents of
       all following "map" lines (without the leading  "map")  in  the  stanza
       provided to it on its standard input. The script must print a string on
       its       standard       output       before        exiting.        See
       /usr/share/doc/ifupdown/examples  for  examples of what the script must
       print.

       Mapping a name consists of searching the remaining mapping patterns and
       running the script corresponding to the first match; the script outputs
       the name to which the original is mapped.

       ifup  is  normally  given  a  physical  interface  name  as  its  first
       non-option  argument.   ifup also uses this name as the initial logical
       name for the interface unless it is accompanied by  a   suffix  of  the
       form  =LOGICAL,  in  which  case  ifup  chooses  LOGICAL as the initial
       logical name for the interface.  It then maps this name, possibly  more
       than  once  according  to  successive mapping specifications,  until no
       further mappings are possible.  If the resulting name is  the  name  of
       some  defined  logical  interface  then  ifup  attempts to bring up the
       physical interface as that logical  interface.   Otherwise  ifup  exits
       with an error.

       Stanzas defining logical interfaces start with a line consisting of the
       word "iface" followed by the name of the logical interface.  In  simple
       configurations  without  mapping stanzas this name should simply be the
       name of the physical interface to which it  is  to  be  applied.   (The
       default mapping script is, in effect, the echo command.)  The interface
       name is followed by the name of the address family that  the  interface
       uses.   This  will  be  "inet" for TCP/IP networking, but there is also
       some support for IPX networking ("ipx"), and IPv6 networking ("inet6").
       Following  that  is  the  name  of  the  method  used  to configure the
       interface.

       Additional options can be given on  subsequent  lines  in  the  stanza.
       Which  options  are  available  depends  on  the  family and method, as
       described below.  Additional options can be  made  available  by  other
       Debian   packages.   For  example,  the  wireless-tools  package  makes
       available a number of options prefixed with "wireless-"  which  can  be
       used  to  configure  the interface using iwconfig(8).  (See wireless(7)
       for details.)

       Options are usually indented for clarity (as in the example above)  but
       are not required to be.

IFACE OPTIONS

       The  following  "command"  options  are  available for every family and
       method.  Each of these options can be given multiple times in a  single
       stanza,  in  which case the commands are executed in the order in which
       they appear in the stanza.  (You can ensure a command  never  fails  by
       suffixing "|| true".)

       pre-up command
              Run  command  before bringing the interface up.  If this command
              fails then ifup aborts, refraining from marking the interface as
              configured,  prints  an  error message, and exits with status 0.
              This behavior may change in the future.

       up command

       post-up command
              Run command after bringing the interface up.   If  this  command
              fails then ifup aborts, refraining from marking the interface as
              configured (even though it has really been  configured),  prints
              an  error  message,  and exits with status 0.  This behavior may
              change in the future.

       down command

       pre-down command
              Run command before taking the interface down.  If  this  command
              fails  then  ifdown  aborts, marks the interface as deconfigured
              (even though it has not really  been  deconfigured),  and  exits
              with status 0.  This behavior may change in the future.

       post-down command
              Run  command  after  taking the interface down.  If this command
              fails then ifdown aborts, marks the interface  as  deconfigured,
              and  exits  with  status  0.   This  behavior  may change in the
              future.

       There exists for each  of  the  above  mentioned  options  a  directory
       /etc/network/if-<option>.d/  the  scripts  in  which  are  run (with no
       arguments)  using  run-parts(8)  after  the  option  itself  has   been
       processed.

       All  of  these  commands  have  access  to  the  following  environment
       variables.

       IFACE  physical name of the interface being processed

       LOGICAL
              logical name of the interface being processed

       ADDRFAM
              address family of the interface

       METHOD method of the interface (e.g., static)

       MODE   start if run from ifup, stop if run from ifdown

       PHASE  as per MODE, but with finer granularity, distinguishing the pre-
              up, post-up, pre-down and post-down phases.

       VERBOSITY
              indicates  whether --verbose was used; set to 1 if so, 0 if not.

       PATH   the  command   search   path:   /usr/local/sbin:/usr/local/bin:
              /usr/sbin:/usr/bin:/sbin:/bin

       Additionally,  all  options given in an interface definition stanza are
       exported to the environment in upper case with "IF_" prepended and with
       hyphens   converted  to  underscores  and  non-alphanumeric  characters
       discarded.

INET ADDRESS FAMILY

       This section documents  the  methods  available  in  the  inet  address
       family.

   The loopback Method
       This method may be used to define the IPv4 loopback interface.

       Options

              (No options)

   The static Method
       This  method  may be used to define ethernet interfaces with statically
       allocated IPv4 addresses.

       Options

              address address
                     Address (dotted quad) required

              netmask netmask
                     Netmask (dotted quad) required

              broadcast broadcast_address
                     Broadcast address (dotted quad)

              network network_address
                     Network address (dotted quad) required for 2.0.x kernels

              metric metric
                     Routing metric for default gateway (integer)

              gateway address
                     Default gateway (dotted quad)

              pointopoint address
                     Address of  other  end  point  (dotted  quad).  Note  the
                     spelling of "point-to".

              media type
                     Medium type, driver dependent

              hwaddress class address
                     Hardware  Address. class is one of ether, ax25, ARCnet or
                     netrom. address is dependent on the above choice.

              mtu size
                     MTU size

   The manual Method
       This method may be used to define interfaces for which no configuration
       is done by default. Such interfaces can be configured manually by means
       of up and down commands or /etc/network/if-*.d scripts.

       Options

              (No options)

   The dhcp Method
       This method may be used to obtain an address via DHCP with any  of  the
       tools:  dhclient, pump, udhcpc, dhcpcd. (They have been listed in their
       order of precedence.) If you have a complicated DHCP setup  you  should
       note  that  some of these clients use their own configuration files and
       do not obtain their configuration information via ifup.

       Options

              hostname hostname
                     Hostname to be requested (pump, dhcpcd, udhcpc)

              leasehours leasehours
                     Preferred lease time in hours (pump)

              leasetime leasetime
                     Preferred lease time in seconds (dhcpcd)

              vendor vendor
                     Vendor class identifier (dhcpcd)

              client client
                     Client identifier (dhcpcd, udhcpc)

              hwaddress class address
                     Hardware Address. class is one of ether, ax25, ARCnet  or
                     netrom. address is dependent on this choice.

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

       Options

              bootfile file
                     Tell the server to use file as the bootfile.

              server address
                     Use  the  IP  address  address  to  communicate  with the
                     server.

              hwaddr addr
                     Use addr as the hardware address instead of  whatever  it
                     really is.

   The ppp Method
       This  method  uses  pon/poff  to  configure  a PPP interface. See those
       commands for details.

       Options

              provider name
                     Use name as the provider (from /etc/ppp/peers).

   The wvdial Method
       This method uses wvdial to configure a PPP interface. See that  command
       for more details.

       Options

              provider name
                     Use name as the provider (from /etc/ppp/peers).

   The ipv4ll Method
       This  method  uses avahi-autoipd to configure an interface with an IPv4
       Link-Layer address (169.254.0.0/16 family). This method is  also  known
       as  "APIPA"  or "IPAC", and often colloquially referred to as "Zeroconf
       address".

       Options

              (No options)

IPX ADDRESS FAMILY

       This section documents the methods available in the ipx address family.

   The static Method
       This  method  may  be  used  to setup an IPX interface. It requires the
       ipx_interface command.

       Options

              frame type
                     type of ethernet frames to use (e.g. 802.2)

              netnum id
                     Network number

   The dynamic Method
       This method may be used to setup an IPX interface dynamically.

       Options

              frame type
                     type of ethernet frames to use (e.g. 802.2)

INET6 ADDRESS FAMILY

       This section documents the  methods  available  in  the  inet6  address
       family.

   The loopback Method
       This method may be used to define the IPv6 loopback interface.

       Options

              (No options)

   The static Method
       This  method  may be used to define interfaces with statically assigned
       IPv6 addresses.

       Options

              address address
                     Address (colon delimited) required

              netmask mask
                     Netmask (number of bits, eg 64) required

              gateway address
                     Default gateway (colon delimited)

              media type
                     Medium type, driver dependent

              hwaddress class address
                     Hardware Address. class is one of ether, ax25, ARCnet  or
                     netrom. address is dependent on this choice.

              mtu size
                     MTU size

   The manual Method
       This method may be used to define interfaces for which no configuration
       is done by default. Such interfaces can be configured manually by means
       of up and down commands or /etc/network/if-*.d scripts.

       Options

              (No options)

   The v4tunnel Method
       This  method may be used to setup an IPv6-over-IPv4 tunnel. It requires
       the ip command from the iproute package.

       Options

              address address
                     Address (colon delimited)

              netmask mask
                     Netmask (number of bits, eg 64)

              endpoint address
                     Address of  other  tunnel  endpoint  (IPv4  dotted  quad)
                     required

              local address
                     Address of the local endpoint (IPv4 dotted quad)

              gateway address
                     Default gateway (colon delimited)

              ttl time
                     TTL setting

KNOWN BUGS/LIMITATIONS

       The  ifup  and ifdown programs work with so-called "physical" interface
       names.   These  names  are  assigned  to  hardware   by   the   kernel.
       Unfortunately  it can happen that the kernel assigns different physical
       interface names to the same hardware at different times;  for  example,
       what  was  called  "eth0" last time you booted is now called "eth1" and
       vice versa.  This creates a  problem  if  you  want  to  configure  the
       interfaces  appropriately.   A  way to deal with this problem is to use
       mapping scripts that choose logical interface names  according  to  the
       properties  of  the  interface  hardware.   See  the get-mac-address.sh
       script in the examples directory for  an  example  of  such  a  mapping
       script.  See also Debian bug #101728.

       It  is not currently possible to divide up /etc/network/interfaces into
       multiple files.  A feature that would make this possible is  some  sort
       of inclusion directive.  No such feature exists in the current ifupdown
       program.  For more information see Debian bug #159884.

AUTHOR

       The    ifupdown    suite    was    written     by     Anthony     Towns
       <aj@azure.humbug.org.au>.   This  manpage  was contributed by Joey Hess
       <joey@kitenet.net>.

SEE ALSO

       ifup(8), iwconfig(8), run-parts(8).

       For advice on configuring this package read the  Network  Configuration
       chapter    of    the    Debian    Reference    manual,   available   at
       http://www.debian.org/doc/manuals/reference/ch-gateway.en.html  or   in
       the debian-reference-en package.

       Examples   of   how   to   set   up   interfaces   can   be   found  in
       /usr/share/doc/ifupdown/examples/network-interfaces.gz.