Installation guide
160 Chapter 12. Network Scripts
configure them. These files are usually named ifcfg- name , where name refers to the name
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:
• 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-
cated.
• DEVICE=
name , where name is the name of the physical device (except
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
/etc/resolv.conf if the PEERDNS directive is set to yes.
• IPADDR=
address , where address is the IP address.
• NETMASK= mask , where mask is the netmask value.
• NETWORK= address , where address is the network address. This directive is deprecated.
• ONBOOT= answer , where answer is one of the following: