CBT Nugget: Linux Server Administration - 13.Identifying Red Hat and CentOS Network Configuration Files

13.Identifying Red Hat and CentOS Network Configuration Files

In Red Hat Enterprise Linux (RHEL) and CentOS, network configuration is managed through several key files and directories. Here are the primary locations and files involved in network configuration:

1. Main Configuration Files:

   • /etc/sysconfig/network: This file contains general network settings, such as whether networking is enabled.
   • /etc/sysconfig/network-scripts/: This directory contains the network interface configuration files.

2. Network Interface Configuration Files:

   Each network interface has a corresponding configuration file located in /etc/sysconfig/network-scripts/. These files are named according to the interface they configure, typically following the format ifcfg-<interface>. For example, the configuration file for the eth0 interface would be /etc/sysconfig/network-scripts/ifcfg-eth0.

3. Key Parameters in Interface Configuration Files (ifcfg-<interface>):

   • DEVICE: The name of the device (e.g., eth0).
   • BOOTPROTO: The method used to obtain an IP address (e.g., static, dhcp).
   • IPADDR: The IP address (if BOOTPROTO is static).
   • NETMASK: The network mask (if BOOTPROTO is static).
   • GATEWAY: The default gateway.
   • DNS1, DNS2: The DNS servers.
   • ONBOOT: Whether the interface should be brought up at boot time (yes or no).

4. Other Network Configuration Files:

   • /etc/hosts: This file maps hostnames to IP addresses.
   • /etc/resolv.conf: This file contains DNS server information.
   • /etc/hostname: This file specifies the system's hostname.
   • /etc/NetworkManager/: This directory contains NetworkManager configurations. NetworkManager can manage network settings if it is installed and running.

5. NetworkManager Tool:

   NetworkManager can manage network configurations dynamically. If NetworkManager is used, the configurations might be stored differently, and the following tools can be used for network management:

   • nmcli: A command-line tool for controlling NetworkManager and reporting network status.
   • nmtui: A text user interface for NetworkManager.

6. Service Control:

   • systemctl restart network: Restarts the network service to apply changes.
   • systemctl restart NetworkManager: Restarts the NetworkManager service (if NetworkManager is being used).

Example of an Interface Configuration File (ifcfg-eth0):

ini
DEVICE=eth0
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=8.8.8.8
DNS2=8.8.4.4

This configuration sets up a static IP address for the eth0 interface, enabling it to start on boot and specifying the necessary network details.

Understanding and correctly configuring these files are crucial for setting up and maintaining network connections on RHEL and CentOS systems.