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NOTE: CentOS Enterprise Linux 5 is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux 5 is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux 5.

13.3. Interface Control Scripts

The interface control scripts activate and deactivated system interfaces. There are two primary interface control scripts that call on control scripts located in the /etc/sysconfig/network-scripts/ directory: /sbin/ifdown and /sbin/ifup.

The ifup and ifdown 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:

ifup eth0

Caution

The ifup and ifdown interface scripts are the only scripts that the user should use to bring up and take down network interfaces.

The following scripts are described for reference purposes only.

Two files used to perform a variety of network initialization tasks during the process of bringing up a network interface are /etc/rc.d/init.d/functions and /etc/sysconfig/network-scripts/network-functions. Refer to Section 13.4, “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 found within the /etc/sysconfig/network-scripts/ directory:

ifup-aliases

Configures IP aliases from interface configuration files when more than one IP address is associated with an interface.

ifup-ippp and ifdown-ippp

Brings ISDN interfaces up and down.

ifup-ipsec and ifdown-ipsec

Brings IPsec interfaces up and down.

ifup-ipv6 and ifdown-ipv6

Brings IPv6 interfaces up and down.

ifup-ipx

Brings up an IPX interface.

ifup-plip

Brings up a PLIP interface.

ifup-plusb

Brings up a USB interface for network connections.

ifup-post and ifdown-post

Contains commands to be executed after an interface is brought up or down.

ifup-ppp and ifdown-ppp

Brings 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.

ifup-sl and ifdown-sl

Brings a SLIP interface up or down.

ifup-wireless

Brings up a wireless interface.

Warning

Removing or modifying any scripts in the /etc/sysconfig/network-scripts/ directory can cause interface connections to act irregularly 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 following command:

/sbin/service network <action>

Here, <action> can be either start, stop, or restart.

To view a list of configured devices and currently active network interfaces, use the following command:

/sbin/service network status

 
 
  Published under the terms of the GNU General Public License Design by Interspire