sudo -s
nano /etc/network/interfaces

auto lo
iface lo inet loopback

auto eth-d
iface eth0 inet static
address etc

auto lo eth0
iface lo inet loopback
iface eth0 inet static
        address xxx.xxx.xxx.xxx(enter your ip here)
        netmask xxx.xxx.xxx.xxx
        gateway xxx.xxx.xxx.xxx(enter gateway ip here,usually the address of the router)
        DNS xxx.xxx.xxx.xxx