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     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) com-
          mands.  This is where you configure how your system is con-
          nected 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 character a backslash.

          The file consists of zero or more "iface", "mapping",
          "auto", "allow-", "rename", "source" and "source-directory"
          stanzas. These will be described in more detail in the fol-
          lowing 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

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          boot time.)  Physical interface names should follow the word
          "auto" on the same line.  There can be multiple "auto" stan-
          zas.  ifup brings the named interfaces up in the order
          listed.

          Lines beginning with "allow-" are used to identify inter-
          faces 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 pre-
          sent, 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 filesystem and the
          interface should stay up until the very end. Note that you
          can still bring down the interface by specifying the inter-
          face name explicitly.

          Lines beginning with "no-scripts" are used to identify
          interfaces for which scripts in /etc/network/if-*.d/ should
          not be run when those interfaces 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 automatically be converted to the latter.  This is

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          mainly useful when ifup is called automatically whenever an
          interface is hotplugged.

          Interface renaming only works if the operating system sup-
          ports it, if an interface is not renamed to another existing
          interface, and may require 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 mul-
          tiple files at once, without specifying them individually or
          using shell globs. Additionally, 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 located at
          /etc/network/interfaces, paths to the included files are
          understood to be under /etc/network.

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

     MAPPINGS
          Stanzas beginning with the word "mapping" are used to deter-
          mine 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 con-
          tain a script definition.  The named script is run with the
          physical interface name as its argument and with the con-
          tents 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.

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          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 accompa-
          nied by a  suffix of the form =LOGICAL, in which case ifup
          chooses LOGICAL as the initial logical name for the inter-
          face.  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.

     INTERFACE DEFINITIONS
          Stanzas defining logical interfaces start with a line con-
          sisting of the word "iface" followed by the name of the log-
          ical 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 map-
          ping 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.)
          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 inter-
          face, 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 advertisement daemon on the network). It can also be
          used to configure multiple addresses of the same type on a

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          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 interface.

     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 following 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, patterns are replaces by all real
          interfaces that are currently known to the operating system
          kernel and whose names match the pattern.  For example,
          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

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          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 interface 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 interface 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 virtual LAN interface. For example, interface
          eth0.1 is a virtual interface with VLAN ID 1 having eth0 as
          its parent interface.

          VLAN interfaces are mostly treated as independent inter-
          faces.  As such, a VLAN interface is normally not automati-
          cally brought up when its parent 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 (either 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 inter-
          faces the kernel knows about, so it is not possible to

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          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 fam-
          ily 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

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               as deconfigured, and exits with status 0.  This behav-
               ior may change in the future.

          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 ifdown commands. These are:

               Scripts in this directory are run before bringing the
               interface up.

               Scripts in this directory are run after bringing the
               interface up.

               Scripts in this directory are run before bringing the
               interface down.

               Scripts in this directory are run after bringing the
               interface down.

          The scripts in which are run (with no arguments) using
          run-parts(8) after 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 directo-
          ries are processed.  Please use if-up.d and if-down.d direc-
          tories 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).

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

          CLASS
               The class of interfaces being processed.  This is a
               copy of the value given to the --allow option when run-
               ning 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 discarded.

          When ifupdown is being called with the --all option, before
          doing anything 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 appropri-
          ate scripts (up or post-down) are executed.

     CONCURRENCY AND PARALLEL EXECUTION
          Ifupdown uses per-interface locking to ensure that concur-
          rent 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 therefore 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 interface than the one that is already being
          (de)configured.  Loops are detected and will result in the
          call failing instead of a deadlock, although it is best if
          one does not rely on that.

     OPTIONS PROVIDED BY OTHER PACKAGES

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          This manual page documents the configuration options pro-
          vided by the ifupdown package.  However, other packages can
          make other options available for use in
          /etc/network/interfaces.  Here is a list of packages that
          provide such extensions:

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

          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 family.

        The loopback Method
          This method may be used to define the IPv4 loopback inter-
          face.

          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 -) depre-
                    cated. Default value: "+"

               metric metric
                    Routing metric for default gateway (integer)

               gateway address

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                    Default gateway (dotted quad)

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

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               vendor vendor_id
                    Vendor class identifier (dhcpcd)

               client client_id
                    Client identifier (dhcpcd), or "no" (dhclient)

               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 what-
                    ever 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 tun-
          nels, 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

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                    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 collo-
          quially 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

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               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 dynami-
          cally.

          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 automati-
          cally 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. Please note that on ifdown, the lease is not cur-
          rently 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+forwarding). 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. Default value: "60"

               ll-interval

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

        The loopback Method
          This method may be used to define the IPv6 loopback inter-
          face.

          Options

               (No options)

        The static Method
          This method may be used to define interfaces with statically
          assigned IPv6 addresses. By default, stateless autoconfigu-
          ration 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+forwarding)

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

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

               scope

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                    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). Default 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 configu-
          ration 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+forwarding). 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

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                    address. Default 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) required

               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 a 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)

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               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 a 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 hard-
          ware 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 inter-
          faces 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

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          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), resolvconf(8).

          For advice on configuring this package read the Network
          Configuration chapter of the Debian Reference manual, avail-
          able at http://www.debian.org/doc/manuals/debian-
          reference/ch05.en.html or in the debian-reference-en pack-
          age.

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

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