Chapter 8. Network
Under Red Hat Enterprise Linux, all network communications occur
between configured software interfaces and
physical networking devices connected to
The configuration files for network interfaces, and the scripts
used to activate and deactivate them, are located in the /etc/sysconfig/network-scripts/ directory. Although
the number and type of interface files can differ from system to
system, there are three categories of files that exist in this
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.
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
/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.
Specifies routing and host information for all network interfaces.
For more information about this file and the directives it accepts,
refer to Section
/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 Section 8.2 Interface
Configuration Files for more information on this type of
file and the directives it accepts.
directory is used by the Network
Administration Tool (system-config-network) and its contents should not
be edited manually. In addition, any use of the Network Administration Tool, even launching the
application, will override any directives previously set in
only one method for network configuration is strongly encouraged,
due to the risk of configuration deletion.
For more information about configuring network interfaces using
the Network Administration Tool, refer
to the chapter titled Network
Configuration in the Red Hat Enterprise
Linux System Administration Guide.