In RHEL/CentOS or Fedora, you can configure network interfaces by using configuration files located in /etc/sysconfig/network-scripts/. For each network interface (e.g., eth0), there should be a corresponding configuration file (e.g., ifcfg-eth0) in the directory. If you would like to configure a network interface, do the following.

$ sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0

If you would like to assign a static IP address to the interface:

DEVICE=eth0
BOOTPROTO=static
HWADDR=00:05:29:E0:4F:3D
IPADDR=10.0.1.10
NETMASK=255.255.255.0
GATEWAY=10.0.1.1
ONBOOT=yes
TYPE=Ethernet

If the interface has IP address assigned by DHCP:

DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:05:29:E0:4F:3D
ONBOOT=yes
TYPE=Ethernet

Once network configuration has been created/updated, you can activate a network interface by running:

$ sudo service network restart

Note that if you are using Desktop version of Linux, you will need to disable NetworkManager first, before attempting to configure interfaces as described above.