Manual Reference Pages  - ifup (8)

NAME

ifup - bring a network interface up

ifdown - take a network interface down

ifquery - parse interface configuration

CONTENTS

Synopsis
Description
Options
Examples
Notes
Files
Known Bugs/limitations
Author
See Also

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...

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

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

DESCRIPTION

The ifup and ifdown commands may be used to configure (or, respectively, deconfigure) network interfaces based on interface definitions in the file /etc/network/interfaces. ifquery command may be used to parse interfaces configuration.

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. Combined with --allow, acts on all interfaces of a specified class instead. 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/network/interfaces to be acted upon.
-i FILE, --interfaces=FILE
  Read interface definitions from FILE instead of from /etc/network/interfaces.
-X PATTERN, --exclude=PATTERN
  Exclude interfaces from the list of interfaces to operate on by the PATTERN. PATTERN uses a usual shell glob syntax. If shell wildcards are not used, it must match the exact interface name. This option may be specified multiple times resulting in more than one pattern being excluded.
-o OPTION=VALUE
  Set OPTION to VALUE as though it were in /etc/network/interfaces.
-n, --no-act
  Don’t configure any interfaces or run any "up" or "down" commands.
--no-mappings
  Don’t run any mappings. See interfaces(5) for more information about the mapping feature.
--no-scripts
  Don’t run any scripts under /etc/network/if-*.d/
-V, --version
  Show copyright and version information.
-v, --verbose
  Show commands as they are executed.
-l, --list
  For ifquery, list all the interfaces which match the specified class. If no class specified, prints all the interfaces listed as auto.

EXAMPLES

ifup -a
  Bring up all the interfaces defined with auto in /etc/network/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.
ifquery -l
  Print names of all interfaces specified with the auto keyword.
ifquery -l --allow=hotplug
  Print names of all interfaces specified with the allow-hotplug keyword.
ifquery eth0
  Display the interface options as specified in the ifupdown configuration. Each key-value pair is printed out on individual line using ": " as separator.

NOTES

ifup, ifdown, and ifquery 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. If that location is not writable (for example, because the root filesystem is mounted read-only for system recovery) then /run/network/ifstate should be made a symbolic link to a writable location. If that is not possible then you can 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 udev(7) or ifplugd(8).

AUTHOR

The ifupdown suite was written by Anthony Towns <aj@azure.humbug.org.au>.

SEE ALSO

interfaces(5), ip(8), ifconfig(8).


IFUPDOWN ifup (8) 22 May 2004
blog comments powered by Disqus