Obviously it’s a bad idea to have a server assigned a different IP address by your DHCP server when it comes up. So here are some basic instructions to set a static IP address on this Ubuntu server.

sudo -s -H
vi /etc/network/interfaces

Then change the following line:

iface eth0 inet dhcp

to:

iface eth0 inet static
     address 192.168.1.100
     netmask 255.255.255.0
     network 192.168.1.0
     broadcast 192.168.1.255
     gateway 192.168.1.254

This is an example only - Obviously you’ll need to work out what to use for each yourself ;)