The first thing we need to do, is open our interfaces file. Execute the following from a terminal.
sudo vi /etc/network/interfaces
sudo nano /etc/network/interfaces
Then add or copy and paste the following.
auto eth0 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 192.168.1.1
Close the file. Now we need to change the DNS settings
sudo vi /etc/resolv.conf
sudo nano /etc/resolv.conf
Edit the nameserver line to something like the following.
Close the file and then restart the networking stuff.
sudo /etc/init.d/networking restart