/etc/network/interfaces
iface wlan0 inet static static address 192.168.1.2 netmask 255.255.255.0 gateway 192.168.1.1
/etc/dhcp.conf
interface wlan0 static ip_address=192.168.1.2/24 static routers=192.168.1.1 static domain_name_servers=192.168.1.1 8.8.8.8 8.8.4.4