Network Interfaces - Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual

Chapter 14.

Network Interfaces

Under Red Hat Enterprise Linux, all network communications occur between configured software
interfaces and physical networking devices connected to the system.
The configuration files for network interfaces are located in the /etc/sysconfig/network-
scripts/ directory. The scripts used to activate and deactivate these network interfaces are also
located here. Although the number and type of interface files can differ from system to system, there
are three categories of files that exist in this directory:
1. Interface configuration files
2. Interface control scripts
3. Network function files
The files in each of these categories work together to enable various network devices.
This chapter explores the relationship between these files and how they are used.
14.1. Network Configuration Files
Before delving into the interface configuration files, let us first itemize the primary configuration files
used in network configuration. Understanding the role these files play in setting up the network stack
can be helpful when customizing a Red Hat Enterprise Linux system.
The primary network configuration files are as follows:
/etc/hosts
The main purpose of this file is to resolve hostnames that cannot be resolved any other way. It
can also be used to resolve hostnames on small networks with no DNS server. Regardless of the
type of network the computer is on, this file should contain a line specifying the IP address of the
loopback device (127.0.0.1) as localhost.localdomain. For more information, refer to the
hosts man page.
/etc/resolv.conf
This file specifies the IP addresses of DNS servers and the search domain. Unless configured to
do otherwise, the network initialization scripts populate this file. For more information about this
file, refer to the resolv.conf man page.
/etc/sysconfig/network
This file specifies routing and host information for all network interfaces. For more information
about this file and the directives it accepts, refer to
network".
/etc/sysconfig/network-scripts/ifcfg-<interface-name>
For each network interface, there is a corresponding interface configuration script. Each of these
files provide information specific to a particular network interface. Refer to
Configuration Files"
for more information on this type of file and the directives it accepts.
Section 28.1.21, "/etc/sysconfig/
Section 14.2, "Interface
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