Here are the steps:
- Execute ifconfig and find out your ethernet configuration name (e.g. eth0)
 - Go to /etc/sysconfig/network-script
 - edit ifcfg-eth0 (depends on your ethernet)
 - Update the file as follow (set the IPADDR, BROADCAST according to your desired configuration)

 - Restart the network service
service network restart 
Here's a brief explanation on the configuration:
- BOOTPROTO : telling the network that we're configuring it as static ip
 - ONBOOT : the configuration will be set at boot time
 - BROADCAST : your gateway
 - NETMASK : your netmask
 
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