Raspbian Jessie
sudo nano /etc/dhcpcd.conf
interface eth0
static ip_address=192.168.1.82/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.162
On Older Raspbian
sudo nano /etc/network/interfaces
address 192.168.1.67
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1