Change a Linux Network Configuration from DHCP to Static IP Address

If you CentOS network configuration is set at DHCP and you want to change your network configuration to a static IP address, then read on.

The network configuration settings are generatlly found and edited in two places.

  1. /etc/sysconfig/network-scripts/ifcfg-eth0
  2. /etc/sysconfig/network

Edit the /etc/sysconfig/network-scripts/ifcfg-eth0 to resemble the following (replace the network addresses with your own).

DEVICE=eth0
USERCTL=no
ONBOOT=yes
BOOTPROTO=none
BROADCAST=192.168.1.255
NETWORK=192.168.1.0
NETMASK=255.255.255.0
IPADDR=192.168.1.5

Edit the /etc/sysconfig/network to resemble the following (replace the network addresses with your own).

NETWORKING=yes
HOSTNAME=name.host.net
FORWARD_IPV4=yes
GATEWAYDEV=
GATEWAY=192.168.1.254
DNS1=192.168.1.1

Alternatively, you can revert back to DHCP by editing /etc/sysconfig/network-scripts/ifcfg-eth0 to resemble the following.

DEVICE=eth0
USERCTL=no
ONBOOT=yes
BOOTPROTO=dhcp
BROADCAST=
NETWORK=
NETMASK=
IPADDR=

Source(s)
http://www.linuxheadquarters.com/howto/networking/networkconfig.shtml