8.2.1. Ethernet Interfaces

8.2.1. Ethernet Interfaces

One of the most common interface files is ifcfg-eth0, which controls the first Ethernet network interface card or NIC in the system. In a system with multiple NICs, there are multiple ifcfg-eth<X> files (where <X> is a unique number corresponding to a specific interface). Because each device has its own configuration file, an administrator can control how each interface functions individually.

The following 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

The Network Administration Tool (system-config-network) is an easy way to make changes to the various network interface configuration files (refer to the chapter titled Network Configuration in the Red Hat Enterprise Linux System Administration Guide for detailed instructions on using this tool).

However, it is also possible to edit the configuration files for a given network interface manually.

Below is a listing of the configurable parameters in an Ethernet interface configuration file:


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