File configurations for each network device you may have or want to add on your system are located in the /etc/sysconfig/network-scripts/ directory with Red Hat Linux 6.1 or 6.2 and are named ifcfg-eth0 for the first interface and ifcfg-eth1 for the second, etc. Following is a example /etc/sysconfig/network-scripts/ifcfg-eth0 file:

DEVICE=eth0
IPADDR=208.164.186.1
NETMASK=255.255.255.0
NETWORK=208.164.186.0
BROADCAST=208.164.186.255
ONBOOT=yes
BOOTPROTO=none
USERCTL=no

If you want to modify your network address manually, or add a new network on a new interface, edit this file -ifcfg-ethN, or create a new one and make the appropriate changes.
* DEVICE=devicename, where devicename is the name of the physical network device.
* IPADDR=ipaddr, where ipaddr is the IP address.
* NETMASK=netmask, where netmask is the netmask IP value.
* NETWORK=network, where network is the network IP address.
* BROADCAST=broadcast, where broadcast is the broadcast IP address.
* ONBOOT=answer, where answer is yes or no. Do the interface need to be active or inactive at boot time.
* BOOTPROTO=proto, where proto is one of the following :
1. none - No boot-time protocol should be used.
2. bootp - The bootp now pump protocol should be used.
3. dhcp - The dhcp protocol should be used.
* USERCTL=answer, where answer is one of the following:
1. yes - Non-root users are allowed to control this device.
2. no - Only the super-user root is allowed to control this device.