8.3. Interface Control Scripts
The interface control scripts activate and deactivated system
interfaces. There are two primary interface control scripts,
/sbin/ifdown and /sbin/ifup,
that call on control scripts located in the
The ifdown and ifup interface
scripts are symbolic links to scripts in the /sbin/
directory. When either of these scripts are called, they require the value
of the interface to be specified, such as:
Determining IP information for eth0... done.
At that point, the /etc/rc.d/init.d/functions and
files are used to perform a variety of tasks. See Section 8.4 Network Function Files for more information.
After verifying that an interface has been specified and that the user
executing the request is allowed to control the interface, the correct
script brings the interface up or down. The following are common
interface control scripts:
ifup-aliases — Configures IP aliases from
interface configuration files when more than one IP address is
associated with an interface.
ifup-cipcb — Used to bring
Crypto IP Encapsulation (CIPE) connections up
ifup-ipv6 — Contains IPv6-related
function calls using environment variables in various interface
configuration files and /etc/sysconfig/network.
ifup-ipx — Used to bring up an IPX interface.
ifup-plip — Used to bring up a PLIP interface.
ifup-plusb — Used to bring up a USB
interface for network connections.
ifdown-post and ifup-post
— Contains commands to be executed after an
interface is brought up or down.
ifdown-ppp and ifup-ppp
— Used to bring a PPP interface up or down.
ifup-routes — Adds static routes for
a device as its interface is brought up.
ifdown-sit and ifup-sit
— Contains function calls related to bringing up and down an
IPv6 tunnel within an IPv4 connection.
ifdown-sl and ifup-sl
— Used to bring a SLIP interface up or down.
Removing or modifying any scripts in the
/etc/sysconfig/network-scripts/ directory can
cause interface connections to act strangely or fail. Only advanced
users should modify scripts related to a network interface.
The easiest way to manipulate all network scripts simultaneously is to
use the /sbin/service command on the network service
(/etc/rc.d/init.d/network), as illustrated the
/sbin/service network <action>
In this example <action> can be either
start, stop, or
To view a list of configured devices and currently active network
interfaces, use the following command: