bring a network interface up
take a network interface down
parse interface configuration
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.
A summary of
options is included below.
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
Force configuration or
deconfiguration of the interface.
If any of the commands of
scripts fails, continue.
Show summary of options.
Only allow interfaces listed in
an allow−CLASS line in
/etc/network/interfaces to be acted upon.
Read interface definitions from
FILE instead of from
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.
Set OPTION to
VALUE as though it were in
Don’t configure any
interfaces or run any "up" or "down"
Don’t run any mappings.
See interfaces(5) for more information about the
Don’t run any scripts
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.
Show copyright and version
Show commands as they are
For ifquery, list all
the interfaces which match the specified class. If no class
specified, prints all the interfaces listed as
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
Bring up all the interfaces
defined with auto in
Bring up interface
Bring up interface eth0
as logical interface home
Bring down all interfaces that
are currently up.
Print names of all interfaces
specified with the auto keyword.
Print names of all interfaces
specified with the allow-hotplug keyword.
Display the interface options
as specified in the ifupdown configuration. Each
key-value pair is printed out on individual line using
": " as separator.
ifdown, and ifquery are actually the same
program called by different names.
does not configure network interfaces directly; it runs low
level utilities such as ip to do its dirty work.
ifdown checks if ifup is still running. In
that case, SIGTERM is sent to ifup.
interface deconfiguration, ifdown ignores errors the
same way as if −−ignore−errors was
definitions of network
interfaces See interfaces(5) for more
current state of network
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.
/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
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
suite was written by Anthony Towns