Chapter 12 Network Scripts; Interface Configuration Files - Red Hat LINUX 7.2 Reference Manual

Section 12.1:Interface Configuration Files
12 Network Scripts
Using Red Hat Linux, all network communications occur between interfaces, which are networking
devices connected to the system, configured in a particular way, and utilizing at least one protocol to
exchange data with other systems. The different types of interfaces that exist are as varied as the de-
vices that support them, such as network interface cards (NICs — commonly called Ethernet cards),
wireless networking PC cards, infrared ports, and more.
The configuration files for the various network interfaces and the scripts to make them active and
inactive are located in the /etc/sysconfig/network-scripts directory. While the existence
of particular interface files can differ from system to system depending on use, the three different
types of files that exist in this directory, interface configuration files, interface control scripts, and
network function files, work together to enable Red Hat Linux to use the various network devices
available.
This chapter will explore the relationship between these files and different options for their use.

12.1 Interface Configuration Files

Interface configuration files control the operation of a particular network interface device. As your
Red Hat Linux system boots, it uses these files to know what interfaces to bring up automatically and
how to configure them to operate correctly. These files are usually named ifcfg- <device> , where
<device> refers to the name of the device that the configuration file controls.
12.1.1 Ethernet Interfaces
One of the most common interface files is ifcfg-eth0, which controls the first NIC in a system. In
a system with many NICs, you will have multiple ifcfg-eth files, each one with number at the end
of the file name. Because each device has its own configuration file, you have a great deal of control
over how each interface functions.
A sample ifcfg-eth0 for a system using a fixed IP address looks similar to this:
DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
BROADCAST=10.0.1.255
NETWORK=10.0.1.0
NETMASK=255.255.255.0
IPADDR=10.0.1.27
USERCTL=no
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