In this example eth0 should get a static ip. This can be done by editing
/etc/network/interfaces:
allow-hotplug eth0 iface eth0 inet static address 192.168.0.2 netmask 255.255.255.0 gateway 192.168.0.1 dns-nameservers 192.168.0.1
This is the entry to configure gateway and dns-server.