ifup - bring a network interface up
ifdown - take a network interface down
ifup [-nv] [--no-act] [--verbose] [-i FILE|--interfaces=FILE] [--allow CLASS] -a|IFACE...
ifdown [-nv] [--no-act] [--verbose] [-i FILE|--interfaces=FILE] [--allow CLASS] -a|IFACE...
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.
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/net-
work/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 configuration or deconfiguration of the interface.
Show summary of options.
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.
-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.
Don't configure any interfaces or run any "up" or "down" commands.
Don't run any mappings. See interfaces(5) for more information about the mapping feature.
Show copyright and version information.
Show commands as they are executed.
Bring up all the interfaces defined with auto in /etc/network/interfaces
Bring up interface eth0
Bring up interface eth0 as logical interface home
Bring down all interfaces that are currently up.
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.
definitions of network interfaces See interfaces(5) for more information.
current state of network interfaces
The program keeps records of whether network interfaces are up or down. Under exceptional circumstances these records can become inconsis-
tent with the real states of the interfaces. For example, an interface that was brought up using ifup and later deconfigured using ifcon-
fig will still be recorded as up. To fix this you can use the --force option to force ifup or ifdown to run configuration or deconfigura-
tion commands despite what it considers the current state of the interface to be.
The file /var/run/network/ifstate must be writable for ifup or ifdown to work properly. On Ubuntu the /var/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 deconfigura-
tion 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 configura-
tion of network interfaces you need to install other packages such as hotplug(8) or ifplugd(8).
The ifupdown suite was written by Anthony Towns <firstname.lastname@example.org>.
interfaces(5), ip(8), ifconfig(8).
22 May 2004 ifup(8)