/etc/network/interfaces

# cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
        address 192.168.0.254
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255

#inet

allow-hotplug eth1
iface eth1 inet static
        address 192.168.1.254
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255
        gateway 192.168.1.253

### wan
allow-hotplug eth2
iface eth2 inet static
        address 192.168.5.254
        netmask 255.255.255.0
        network 192.168.5.0
        broadcast 192.168.5.255