Create a connection with a fixed IP address
Most networks will automatically assign anand other details to your computer when you connect to the network. These details can change periodically, but you might want to have a fixed IP address for the computer so you always know what its address is (for example, if it is a file server).
To give your computer a fixed (static) IP address:
Click the network menu on the menu bar and select Edit Connections.
Select the Auto eth connection on the Wired tab or your WiFi network on the Wireless tab and click Edit.
Click on the IPv4 Settings tab and change the Method to Manual.
If no connection information is listed in the Addresses list, or if you want to set up a new connection, click Add.
Enter the IP Address, Netmask, and Gateway information into the appropriate boxes. How you choose these will depend on your network setup; there are specific rules governing which IP addresses and netmasks are valid for a given network.
If necessary, enter a Domain Name Server address into the DNS servers box. This is the IP address of a server which looks up domain names; most corporate networks and internet providers have dedicated DNS servers.
Click Save. The network connection should now have a fixed IP address.