160

Chapter 12. Network Scripts

configure them. These files are usually named

ifcfg  name

, where

name

refers to the name

X

Y

X

Y

of the device that the configuration file controls.

12.2.1. Ethernet Interfaces

One of the most common interface files is

ifcfg eth0

, which controls the first network interface

card or NIC in the system. In a system with multiple NICs, you will also have multiple

ifcfg eth

files, each one with a unique number at the end of the file name. Because each device has its own

configuration file, you can control how each interface functions individually.

Below is a sample

ifcfg eth0

file for a system using a fixed IP address:

DEVICE=eth0

BOOTPROTO=none

ONBOOT=yes

NETWORK=10.0.1.0

NETMASK=255.255.255.0

IPADDR=10.0.1.27

USERCTL=no

The values required in an interface configuration file can change based on other values. For example,

the

ifcfg eth0

file for an interface using DHCP looks quite a bit different, because IP information

is provided by the DHCP server:

DEVICE=eth0

BOOTPROTO=dhcp

ONBOOT=yes

Most of the time you will probably want to use a GUI utility, such as Network Administration Tool

(

redhat config network

) to make changes to the various interface configuration files. See the

Official Red Hat Linux Customization Guide for instructions on using this tool.

You can also edit the configuration file for a given network interface by hand. Below is a listing of the

parameters one can expect to configure in an interface configuration file.

Within each of the interface configuration files, the following values are common:

  BOOTPROTO= protocol

, where

protocol

is one of the following:

X

Y

X

Y

none

  No boot time protocol should be used.

bootp

  The BOOTP protocol should be used.

dhcp

  The DHCP protocol should be used.

  BROADCAST= address

, where

address

is the broadcast address. This directive is depre 

X

Y

X

Y

cated.

  DEVICE= name

, where

name

is

the

name

of

the

physical

device

(except

X

Y

X

Y

dynamically allocated PPP devices where it is the logical name).

  DNS{1,2}= address

, where

address

is a name server address to be placed in

X

Y

X

Y

/etc/resolv.conf

if the

PEERDNS

directive is set to

yes

.

  IPADDR= address

, where

address

is the IP address.

X

Y

X

Y

  NETMASK= mask

, where

mask

is the netmask value.

X

Y

X

Y

  NETWORK= address

, where

address

is the network address. This directive is deprecated.

X

Y

X

Y

  ONBOOT= answer

, where

answer

is one of the following:

X

Y

X

Y