ifup


       ifdown - take a network interface down

SYNOPSIS
       ifup  [-nv] [--no-act] [--verbose] [-i FILE|--interfaces=FILE] [--allow
       CLASS] -a|IFACE...
       ifup -h|--help
       ifup -V|--version

       ifdown  [-nv]  [--no-act]   [--verbose]   [-i   FILE|--interfaces=FILE]
       [--allow CLASS] -a|IFACE...

DESCRIPTION
       The  ifup  and  ifdown  commands  may be used to configure (or, respec-
       tively, deconfigure) network interfaces based on interface  definitions
       in the file /etc/network/interfaces.

OPTIONS
       A summary of options is included below.

       -a, --all
              If given to ifup, affect all interfaces marked auto.  Interfaces
              are brought up in  the  order  in  which  they  are  defined  in
              /etc/network/interfaces.  If given to ifdown, affect all defined
              interfaces.  Interfaces are brought down in the order  in  which
              they  are  currently  listed  in the state file. Only interfaces
              defined in /etc/network/interfaces will be brought down.

       --force
              Force configuration or deconfiguration of the interface.

       -h, --help
              Show summary of options.

       --allow=CLASS
              Only allow interfaces listed in an allow-CLASS line in /etc/net-
              work/interfaces to be acted upon.

       -i FILE, --interfaces=FILE
              Read  interface  definitions from FILE instead of from /etc/net-
              work/interfaces.

       -e PATTERN, --exclude=PATTERN
              Exclude interfaces from the list of interfaces to operate on  by
              the  PATTERN.   Notice  that the PATTERN can be a full interface
              name or substrings that match  interfaces.  Users  could  easily
              have  unexpected  behaviour if they use a small string to do the
              match.

       -n, --no-act
              Don't configure any interfaces or run any "up"  or  "down"  com-
              mands.

       --no-mappings
              work/interfaces

       ifup eth0
              Bring up interface eth0

       ifup eth0=home
              Bring up interface eth0 as logical interface home

       ifdown -a
              Bring down all interfaces that are currently up.

NOTES
       ifup  and  ifdown  are  actually  the  same program called by different
       names.

       The program does not configure network interfaces directly; it runs low
       level utilities such as ip to do its dirty work.

       When  invoked,  ifdown  checks  if ifup is still running. In that case,
       SIGTERM is sent to ifup.

FILES
       /etc/network/interfaces
              definitions of network interfaces  See  interfaces(5)  for  more
              information.

       /run/network/ifstate
              current state of network interfaces

KNOWN BUGS/LIMITATIONS
       The program keeps records of whether network interfaces are up or down.
       Under exceptional circumstances these records can  become  inconsistent
       with the real states of the interfaces.  For example, an interface that
       was brought up using ifup and later deconfigured  using  ifconfig  will
       still be recorded as up.  To fix this you can use the --force option to
       force ifup or ifdown to run configuration or  deconfiguration  commands
       despite what it considers the current state of the interface to be.

       The  file  /run/network/ifstate  must be writable for ifup or ifdown to
       work properly.  On Ubuntu the /run location is a  temporary  filesystem
       which is always writable and thrown away on shutdown.  You can also use
       the --force option to run  configuration  or  deconfiguration  commands
       without updating the file.

       Note  that  the program does not run automatically: ifup alone does not
       bring up interfaces that appear as a result of hardware being installed
       and  ifdown  alone  does  not bring down interfaces that disappear as a
       result of hardware being removed.  To  automate  the  configuration  of
       network  interfaces  you  need  to  install other packages such as hot-
       plug(8) or ifplugd(8).

AUTHOR
       The  ifupdown  suite  was  written  by  Anthony  Towns   <aj@azure.hum-
       bug.org.au>.
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