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] [
--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...
ifquery --state [
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.
- --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.
- -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
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).