interfaces

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 infor-
       mation  for the ifup(8) and ifdown(8) commands.  This is where you con-
       figure how your system is connected to the network.

EXAMPLE
       The following  example  configures  two  network  interfaces:  eth0  is
       brought  up at boot, and uses DHCP for IPv4 and SLAAC for IPv6, whereas
       eth1 is brought up whenever the network hardware is  detected,  and  is
       configured with static IPv4 and IPv6 addresses.

       auto eth0
       allow-hotplug eth1

       iface eth0 inet dhcp

       iface eth0 inet6 auto

       iface eth1 inet static
            address 192.168.1.2/24
            gateway 192.168.1.1

       iface eth1 inet6 static
            address fec0:0:0:1::2/64
            gateway fec0:0:0:1::1

FILE FORMAT
       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-",
       "rename", "source" and "source-directory" stanzas. These  will  be  de-
       scribed in more detail in the following sections.

INTERFACE SELECTION
       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  also  used by the system boot scripts, so interfaces marked
       "auto" are brought up at boot time.)  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 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.   (Interfaces
       marked "allow-hotplug" are brought up when udev detects them.  This can
       either be during boot if the interface is  already  present,  or  at  a
       later  time,  for  example when plugging in a USB network card.  Please
       note that this does not have anything to do with  detecting  a  network
       cable being plugged in.)

       Lines  beginning  with  "no-auto-down"  are used to identify interfaces
       that should not be brought down by the command "ifdown  -a".  Its  main
       use  is  to  prevent an interface from being brought down during system
       shutdown time, for example if the root filesystem is a network filesys-
       tem  and the interface should stay up until the very end. Note that you
       can still bring down the interface by specifying the interface name ex-
       plicitly.

       Lines  beginning  with "no-scripts" are used to identify interfaces for
       which scripts in /etc/network/if-*.d/ should not be run when those  in-
       terfaces  are  brought  up or down.  he above will match eth0 and eth1,
       and will bring up both interfaces using the "iface eth" stanza.

INTERFACE RENAMING
       Lines beginning with "rename" are used to rename interfaces.  It  takes
       one  or  more arguments in the form of "CUR=NEW", where CUR is the name
       of an existing interface, and NEW is the new name.  This  becomes  very
       powerful when combined with pattern matching for the CUR interface.

       Interfaces  are  renamed whenever "ifup" is called.  Renaming logically
       happens before anything else is done.  So if an  interface  is  started
       with  the  name "foo", and it has to be renamed to "bar" and brought up
       at boot time, then one should use the following /etc/network/interfaces
       file:

       rename foo=bar
       auto bar
       iface bar ...

       However,  if  the  interface  is not renamed yet, it is possible to use
       both "ifup foo" and "ifup bar".  The former command will then automati-
       cally  be  converted to the latter.  This is mainly useful when ifup is
       called automatically whenever an interface is hotplugged.

       Interface renaming only works if the operating system supports  it,  if
       an  interface is not renamed to another existing interface, and may re-
       quire that the interface that is to be renamed has not been brought  up
       yet.   If  ifup tries to rename an interface and it fails, it will exit
       with an error.

INCLUDING OTHER FILES
       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.)

       Similarly,  "source-directory" keyword is used to source multiple files
       at once, without specifying them individually or using shell globs. Ad-
       ditionally,  when  "source-directory"  is  used, names of the files are
       checked to match the following regular expression: ^[a-zA-Z0-9_-]+$. In
       other words, the names must consist entirely of ASCII upper- and lower-
       case letters, ASCII digits, ASCII underscores, and ASCII minus-hyphens.
       In the directory path, shell wildcards may be used as well.

       When  sourcing  files  or directories, if a path doesn't have a leading
       slash, it's considered relative to the directory containing the file in
       which  the  keyword is placed. In the example above, if the file is lo-
       cated at /etc/network/interfaces, paths to the included files  are  un-
       derstood to be under /etc/network.

       By  default,  on a freshly installed Debian system, the interfaces file
       includes a line to source files in the /etc/network/interfaces.d direc-
       tory.

MAPPINGS
       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/exam-
       ples 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-op-
       tion  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  de-
       fined logical interface then ifup attempts to bring up the physical in-
       terface as that logical interface.  Otherwise ifup exits with an error.

INTERFACE DEFINITIONS
       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 de-
       fault 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  de-
       scribed  below.   Additional options can be made available by other De-
       bian packages.  For example, the wireless-tools package makes available
       a number of options prefixed with "wireless-" which can be used to con-
       figure the interface using iwconfig(8).  (See wireless(7) for details.)
       A  list  of  packages  providing additional options is mentioned in the
       section "OPTIONS PROVIDED BY OTHER PACKAGE".

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

       Multiple  "iface" stanzas can be given for the same interface, in which
       case all of the configured addresses and  options  for  that  interface
       will  be  applied  when  bringing up that interface.  This is useful to
       configure both IPv4 and IPv6 addresses on the same interface  (although
       if  no  inet6 stanza is present, the kernel will normally still perform
       stateless address autoconfiguration if there is an  IPv6  route  adver-
       tisement  daemon on the network). It can also be used to configure mul-
       tiple addresses of the same type on a single interface.

INTERFACE TEMPLATES
       It is possible to define interface definition templates and extend them
       using the inherits keyword:

       iface ethernet inet static
            mtu 1500
            hwaddress 11:22:33:44:55:66

       iface eth0 inet static inherits ethernet
            address 192.168.1.2/24

       This  may  be useful to separate link-level settings shared by multiple
       interfaces from, for example, IP address settings specific to every in-
       terface.

PATTERN MATCHING INTERFACES
       It  is  possible  to use patterns to match one or more real interfaces.
       These patterns can currently appear in  lines  beginning  with  "auto",
       "allow-",  "rename" and on the command line.  A pattern has the follow-
       ing format (see below for exceptions for GNU/Hurd):

       [VARIABLE]/VALUE[/[OPTIONS]][=LOGICAL]

       If no VARIABLE is  given,  this  pattern  will  match  interface  names
       against the given VALUE.  VALUE can contain wildcard patterns such as ?
       and *, see the fnmatch(3) function.  When ifup or ifdown is  run,  pat-
       terns  are  replaces by all real interfaces that are currently known to
       the operating system kernel and whose names match the pattern.  For ex-
       ample, given the following line:

       auto /eth*

       If  the kernel knows about the interfaces with names lo, eth0 and eth1,
       then the above line is then interpreted as:

       auto eth0 eth1

       Note that there must still be valid "iface" stanzas for  each  matching
       interface.  However, it is possible to combine a pattern with a mapping
       to a logical interface, like so:

       auto /eth*=eth
       iface eth inet dhcp

       Valid variable names are "mac", in which case value is matched  against
       the  interface's  MAC address.  On Linux, the variable name can also be
       any filename in /sys/class/net/<iface>/, in which  case  the  value  is
       matched against the contents of the corresponding file.

       The  OPTIONS field currently only supports a number. If given, only the
       n-th interface that has a matching value will actually be used, where n
       is the number given, starting at 1. So /eth*/1 will match the first in-
       terface whose name starts with eth.

       On GNU/Hurd, interface names  start  with  /dev/,  and  this  obviously
       clashes with the format for patterns.  To ensure an interface name like
       /dev/eth0 does not get interpreted  as  a  pattern,  any  pattern  that
       starts  with /dev/ is ignored, and instead interpreted as a literal in-
       terface name.  To make  a  pattern  that  matches  interface  names  on
       GNU/Hurd, use something like:

       auto /?dev?eth*=eth
       iface eth inet dhcp

VLAN INTERFACES
       To  ease  the  configuration  of  VLAN  interfaces, interfaces having .
       (full stop character) in the name are configured as 802.1q tagged  vir-
       tual  LAN  interface. For example, interface eth0.1 is a virtual inter-
       face with VLAN ID 1 having eth0 as its parent interface.

       VLAN interfaces are mostly treated as independent interfaces.  As such,
       a VLAN interface is normally not automatically brought up when its par-
       ent interface is brought up.  The exception is when ifup is called with
       the  --allow  option, in which case all VLAN interfaces that are in the
       same allow class as the parent interface are brought up  together  with
       the parent interface.  For example:

       allow-hotplug eth0 eth0.1

       iface eth0 inet static
            address ...

       iface eth0.1 inet static
            address ...

       iface eth0.2 inet static
            address ...

       In  the  above example, when "ifup --allow hotplug eth0" is called (ei-
       ther manually or because udev triggers this when a  network  device  is
       hotplugged),  the  interface  eth0  and  the  VLAN interface eth0.1 are
       brought up, but eth0.2 is not.

       Keep in mind that pattern matching will only match interfaces the  ker-
       nel  knows  about,  so it is not possible to specify "auto /eth0.*" and
       have all VLAN interfaces for eth0 be brought up at boot time.   Another
       way  to  ensure  that a VLAN interface is brought up automatically when
       the parent interface is brought up, is to use a recursive call to ifup,
       like so:

       iface eth0 inet manual
            up ifup eth0.3

       iface eth0.3 inet static
            address ...

       Note  that  there  is  no need to add an explicit call to ifdown, since
       VLAN interfaces are automatically brought down  whenever  their  parent
       interfaces are brought down.

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 them with "|| 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 fu-
              ture.

       description name
              Alias interface by name

HOOK SCRIPTS
       There are four directories in which scripts can be  placed  which  will
       always  be  run for any interface during certain phases of ifup and if-
       down commands. These are:

       /etc/network/if-pre-up.d/
              Scripts in this directory are run before bringing the  interface
              up.

       /etc/network/if-up.d/
              Scripts  in  this directory are run after bringing the interface
              up.

       /etc/network/if-down.d/
              Scripts in this directory are run before bringing the  interface
              down.

       /etc/network/if-post-down.d/
              Scripts  in  this directory are run after bringing the interface
              down.

       The scripts in which are run (with no arguments) using run-parts(8) af-
       ter  the  corresponding  pre-up,  up, down and post-down options in the
       /etc/network/interfaces file itself have 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  directo-
       ries instead.

ENVIRONMENT VARIABLES
       All  hook  scripts,  and  the commands executed by pre-up, up, post-up,
       pre-down, down and post-down have access to the  following  environment
       variables:

       IFACE  The  physical  name of the interface being processed, or "--all"
              (see below).

       LOGICAL
              The logical name of the interface  being  processed,  or  "auto"
              (see below).

       ADDRFAM
              The address family of the interface, or "meta" (see below).

       METHOD The  method  of the interface (e.g., static), or "none" (see be-
              low).

       CLASS  The class of interfaces being processed.  This is a copy of  the
              value  given  to the --allow option when running ifup or ifdown,
              otherwise it is set to "auto" when the --all option is used.

       CLASS  The class of interfaces being processed.  This is a copy of  the
              value  given  to the --allow option when running ifup or ifdown,
              otherwise it is set to "auto" when the --all option is used.

       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.

       When  ifupdown is being called with the --all option, before doing any-
       thing to interfaces, it calls all the hook  scripts  (pre-up  or  down)
       with  IFACE set to "--all", LOGICAL set to the current value of --allow
       parameter  (or  "auto"   if   it's   not   set),   ADDRFAM="meta"   and
       METHOD="none".   After all the interfaces have been brought up or taken
       down, the appropriate scripts (up or post-down) are executed.

CONCURRENCY AND PARALLEL EXECUTION
       Ifupdown uses per-interface locking to ensure that concurrent ifup  and
       ifdown  calls  to the same interface are run in serial.  However, calls
       to different interfaces will be able to run in parallel.  It is  there-
       fore important that any hook scripts and pre-up, up, down and post-down
       commands are written with the  possibility  of  parallel  execution  in
       mind.

       It is allowed to recursively call ifup and ifdown from hook scripts and
       interface commands, as long as these calls refer to a different  inter-
       face  than the one that is already being (de)configured.  Loops are de-
       tected and will result in the call failing instead of a  deadlock,  al-
       though it is best if one does not rely on that.

OPTIONS PROVIDED BY OTHER PACKAGES
       This  manual  page  documents the configuration options provided by the
       ifupdown package.  However,  other  packages  can  make  other  options
       available  for use in /etc/network/interfaces.  Here is a list of pack-
       ages that provide such extensions:

       arping, avahi-autoipd, avahi-daemon, bind9, bridge-utils, clamav-fresh-
       clam,  controlaula,  epoptes-client,  ethtool,  guidedog, hostap-utils,
       hostapd, htpdate, ifenslave, ifmetric, ifupdown-extra,  ifupdown-multi,
       ifupdown-scripts-zg2,  initscripts, isatapd, linux-wlan-ng, lprng, mac-
       changer, miredo, nslcd, ntpdate, openntpd, openresolv,  openssh-server,
       openvpn, openvswitch-switch, postfix, resolvconf, sendmail-base, shore-
       wall-init, slrn, slrnpull,  tinc,  ucarp,  uml-utilities,  uruk,  vde2,
       vlan,  vzctl,  whereami, wide-dhcpv6-client, wireless-tools, wpasuppli-
       cant.

       Please consult the documentation  of  those  packages  for  information
       about how they extend ifupdown.

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
       allocated IPv4 addresses.

       Options

              address address
                     Address (dotted quad/netmask) required

              netmask mask
                     Netmask (dotted quad or number of bits) deprecated

              broadcast broadcast_address
                     Broadcast  address  (dotted quad, + or -) deprecated. De-
                     fault 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 spell-
                     ing of "point-to".

              hwaddress address
                     Link local address or "random".

              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
                     Link local address or "random".

              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)

              metric metric
                     Metric for added routes (dhclient)

              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)

              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

              metric metric
                     Routing metric for default gateway (integer)

              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
                     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  ad-
       dress".

       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 as-
       signed 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.
       Please  note  that  on  ifdown,  the lease is not currently released (a
       known bug).

       Options

              privext int
                     Privacy extensions (RFC4941) (0=off, 1=assign, 2=prefer)

              accept_ra int
                     Accept router advertisements (0=off, 1=on,  2=on+forward-
                     ing). Default value: "2"

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

              request_prefix int
                     Request a prefix through DHCPv6 Prefix Delegation (0=off,
                     1=on). Default value: "0"

              ll-attempts
                     Number of attempts to wait for a link-local address.  De-
                     fault value: "60"

              ll-interval
                     Link-local  address  polling interval in seconds. Default
                     value: "0.1"

   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/netmask) required

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

              metric metric
                     Routing metric for default gateway (integer)

              gateway address
                     Default gateway (colon delimited)

              media type
                     Medium type, driver dependent

              hwaddress address
                     Hardware address or "random"

              mtu size
                     MTU size

              accept_ra int
                     Accept router advertisements (0=off, 1=on,  2=on+forward-
                     ing)

              autoconf int
                     Perform  stateless  autoconfiguration  (0=off, 1=on). De-
                     fault value: "0"

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

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

              preferred-lifetime int
                     Time that address remains preferred

              dad-attempts
                     Number  of attempts to settle DAD (0 to disable DAD). De-
                     fault value: "60"

              dad-interval
                     DAD state polling interval  in  seconds.  Default  value:
                     "0.1"

   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 or "random"

              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 or "random"

              accept_ra int
                     Accept  router advertisements (0=off, 1=on, 2=on+forward-
                     ing). Default value: "1"

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

              request_prefix int
                     Request a prefix through DHCPv6 Prefix Delegation (0=off,
                     1=on). Default value: "0"

              ll-attempts
                     Number  of attempts to wait for a link-local address. De-
                     fault value: "60"

              ll-interval
                     Link-local address polling interval in  seconds.  Default
                     value: "0.1"

   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) required

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

              endpoint address
                     Address of other tunnel endpoint (IPv4 dotted  quad)  re-
                     quired

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

              metric metric
                     Routing metric for default gateway (integer)

              gateway address
                     Default gateway (colon delimited)

              ttl time
                     TTL setting

              mtu size
                     MTU size

              preferred-lifetime int
                     Time that address remains preferred

   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

              metric metric
                     Routing metric for default gateway (integer)

              ttl time
                     TTL setting

              mtu size
                     MTU size

              preferred-lifetime int
                     Time that address remains preferred

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)  in-
       terface. 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.   Unfortu-
       nately  it can happen that the kernel assigns different physical inter-
       face 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.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), resolvconf(8).

       For  advice  on configuring this package read the Network Configuration
       chapter of the Debian Reference  manual,  available  at  http://www.de-
       bian.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                         24 July 2017                    INTERFACES(5)
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