interfaces

       ifdown

DESCRIPTION
       /etc/network/interfaces contains network interface configuration infor-
       mation  for the ifup(8) and ifdown(8) commands.  This is where you con-
       figure 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 charac-
       ter a backslash.

       The file consists of zero or more "iface", "mapping", "auto",  "allow-"
       and "source" stanzas. Here is an example.
       auto lo eth0
       allow-hotplug eth1

       iface lo inet loopback

       source interfaces.d/machine-dependent

       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.

       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.  (See wordexp(3) for details.)

       Stanzas  beginning  with the word "mapping" are used to determine how a
       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 logi-
       cal 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 inter-
       face.

       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 avail-
       able 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
              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 argu-
       ments) using run-parts(8) after the option itself has  been  processed.
       Please  note  that as post-up and pre-down are aliases, no files in the
       corresponding directories are processed.  Please use  if-up.d  and  if-
       down.d directories instead.

       All  of  these  commands have access to the following environment vari-
       ables.

       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  dis-
       carded.

INET ADDRESS FAMILY
       This  section  documents the methods available in the inet address fam-
       ily.

   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

              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 spell-
                     ing of "point-to".

              hwaddress address
                     Link local address.

              mtu size
                     MTU size

              scope  Address validity scope. Possible  values:  global,  link,
                     host

   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

              hwaddress address
                     Hardware address

              mtu size
                     MTU size

   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)

                     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 tunnel Method
       This method is used to create GRE or IPIP tunnels. You need to have the
       ip binary from the iproute package. For GRE tunnels, you will  need  to
       load the ip_gre module and the ipip module for IPIP tunnels.

       Options

              address address
                     Local address (dotted quad) required

              mode type
                     Tunnel type (either GRE or IPIP) required

              endpoint address
                     Address of other tunnel endpoint required

              dstaddr address
                     Remote address (remote address inside tunnel)

              local address
                     Address of the local endpoint

              gateway address
                     Default gateway

              ttl time
                     TTL setting

              mtu size
                     MTU size

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

       Options

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

              unit number
                     Use number as the ppp unit number.

              options string

       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 fam-
       ily.

   The auto Method
       This method  may  be  used  to  define  interfaces  with  automatically
       assigned IPv6 addresses. Using this method on its own doesn't mean that
       RDNSS options will be applied, too. To make this happen, rdnssd  daemon
       must be installed, properly configured and running. If stateless DHCPv6
       support is turned on, then additional network configuration  parameters
       such as DNS and NTP servers will be retrieved from a DHCP server.

       Options

              privext int
                     Privacy extensions (RFC3041) (0=off, 1=assign, 2=prefer)

              dhcp int
                     Use stateless DHCPv6 (0=off, 1=on)

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

              mtu size
                     MTU size

              accept_ra int
                     Accept router advertisements (0=off, 1=on)

              autoconf int
                     Perform stateless autoconfiguration (0=off, 1=on)

              privext int
                     Privacy extensions (RFC3041) (0=off, 1=assign, 2=prefer)

              scope  Address  validity  scope.  Possible values: global, site,
                     link, host

   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

              hwaddress address
                     Link local address.

              mtu size
                     MTU size

   The dhcp Method
       This method may be used to obtain network interface  configuration  via
       stateful  DHCPv6  with dhclient. In stateful DHCPv6, the DHCP server is
       responsible for assigning addresses to clients.

       Options

              hwaddress address
                     Hardware address

   The v4tunnel Method
                     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

              mtu size
                     MTU size

   The 6to4 Method
       This method may be used to setup an 6to4 tunnel.  It  requires  the  ip
       command from the iproute package.

       Options

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

              ttl time
                     TTL setting

              mtu size
                     MTU size

CAN ADDRESS FAMILY
       This section documents the methods available in the can address family.

   The static Method
       This  method  may  be  used  to  setup an Controller Area Network (CAN)
       interface. It requires the the ip command from the iproute package.

       Options

              bitrate bitrate
                     bitrate (1..1000000) required

              samplepoint samplepoint
                     sample point (0.000..0.999)

              loopback loopback
                     loop back CAN Messages (on|off)

              listenonly listenonly
                     listen only mode (on|off)

              triple triple
                     activate triple sampling (on|off)

       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.

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

SEE ALSO
       ifup(8), ip(8), ifconfig(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/debian-reference/ch05.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.



ifupdown                         5 April 2004                    INTERFACES(5)
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