ifup
Section: (8)
Updated: 11 Jan 2017
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NAME
ifup - bring a network interface up
ifdown - take a network interface down
ifquery - parse interface configuration
SYNOPSIS
ifup
[-nv]
[--no-act]
[--verbose]
[-i FILE|--interfaces=FILE]
[--state-dir=DIR]
[--allow CLASS]
-a|IFACE...
ifup
-h|--help
ifup
-V|--version
ifdown
[-nv]
[--no-act]
[--verbose]
[-i FILE|--interfaces=FILE]
[--state-dir=DIR]
[--allow CLASS]
-a|IFACE...
ifquery
[-nv]
[--verbose]
[-i FILE|--interfaces=FILE]
[--state-dir=DIR]
[--allow CLASS]
IFACE...
ifquery
-l|--list
[-nv]
[--verbose]
[-i FILE|--interfaces=FILE]
[--state-dir=DIR]
[--allow CLASS]
[-a|IFACE...]
ifquery
--state
[--state-dir=DIR]
[--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.
- -f, --force
-
Force configuration or deconfiguration of the interface.
- --ignore-errors
-
If any of the commands of scripts fails, continue.
- -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.
- --state-dir=DIR
-
Keep interface state in
DIR
instead of in
/run/network.
- -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/
- --no-loopback
-
Disable special handling of the loopback interface. By default, the loopback interface
(lo on Linux) is predefined internally as an auto interface, so it's brought up
on ifup -a automatically. In the case the loopback device is redefined by user,
the interface is configured just once anyway. If, however, another interface is also
defined as loopback, it's configured as usual. Specifying this option disables this
behaviour, so the loopback interface won't be configured automatically.
- -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.
- --state
-
For ifquery, dump the state of the interfaces. When no interfaces specified,
lists all interfaces brought up together with logical interfaces assigned to them and
exits with a status code indicating success. If one or more interfaces specified,
display state of these interfaces only; successful code is returned if all of interfaces
given as arguments are up. Otherwise, 0 is returned.
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.
During interface deconfiguration,
ifdown
ignores errors the same way as if
--ignore-errors
was specified.
FILES
- /etc/network/interfaces
-
definitions of network interfaces
See
interfaces(5)
for more information.
- /run/network/ifstate
-
current state of network interfaces
CONCURRENCY
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.
EXIT STATUS
For
ifup
and
ifdown,
the exit status will be 0 if the given interface(s) have all been (de)configured successfully, 1 if there was any error.
The result of these commands is idempotent; running
ifup
on an interface that is already up will result in an exit status of 0, and similarly running
ifdown
on an interface that is not up will also result in an exit status of 0.
ifquery
will normally return with exit status 0 if an interface with a matching iface stanza, 1 if there is no matching stanza.
ifquery --state
will also return with exit status 1 if the given interface was known but was not up.
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).
AUTHORS
The ifupdown suite was created by Anthony Towns <aj@azure.humbug.org.au>,
currently maintained by Santiago Ruano Rincón <santiago@debian.org> and
Josue Ortega <josue@debian.org>
Many others have helped develop ifupdown over time, see
/usr/share/doc/ifupdown/changelog.Debian.gz for a full history.
SEE ALSO
interfaces(5),
ip(8),
ifconfig(8).
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- EXAMPLES
-
- NOTES
-
- FILES
-
- CONCURRENCY
-
- EXIT STATUS
-
- KNOWN BUGS/LIMITATIONS
-
- AUTHORS
-
- SEE ALSO
-
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