INTERFACES(5)                                                    File formats                                                    INTERFACES(5)

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", "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 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. 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 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/netmask) required

              netmask mask
                     Netmask (dotted quad or CIDR)

              broadcast broadcast_address
                     Broadcast address (dotted quad, + or -) Default value: +

              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".

              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

              (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 address
                     Hardware Address.

   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 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 commands 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
                     Pass string as additional options to pon.

   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/wvdial.conf).

   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 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.

       Options

              (No options)

   The static Method
       This  method  may  be  used  to  define  interfaces with statically assigned IPv6 addresses. By default, stateless autoconfiguration is
       disabled for this interface.

       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 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

              (No options)

   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
       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

              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)

              oneshot oneshot
                     one shot mode (on|off)

              berr berr
                     activate berr reporting (on|off)

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.

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), 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.
 

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