18.3. Configuring a DHCP Client

The first step for configuring a DHCP client is to make sure the kernel recognizes the network interface card. Most cards are recognized during the installation process, and the system is configured to use the correct kernel module for the card. If you install a card after installation, Kudzu [1] should recognize it and prompt you to configure the corresponding kernel module for it. Be sure to check the Red Hat Linux Hardware Compatibility List available at http://hardware.redhat.com/hcl/. If the network card is not configured by the installation program or Kudzu and you know which kernel module to load for it, refer to Chapter 31 Kernel Modules for details on loading kernel modules.

To configure a DHCP client manually, you need to modify the /etc/sysconfig/network file to enable networking and the configuration file for each network device in the /etc/sysconfig/network-scripts directory. In this directory, each device should have a configuration file named ifcfg-eth0 where eth0 is the network device name.

The /etc/sysconfig/network file should contain the following line:

NETWORKING=yes

You might have more information in this file, but the NETWORKING variable must be set to yes if you want networking to start at boot time.

The /etc/sysconfig/network-scripts/ifcfg-eth0 file should contain the following lines:

DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes

You need a configuration file for each device that you want to configure to use DHCP.

If you prefer a graphical interface for configuring a DHCP client, refer to Chapter 12 Network Configuration for details on using Network Administration Tool to configure a network interface to use DHCP.