auto tun0
iface tun0
	tunnel-local 203.0.113.2
	tunnel-remote 203.0.113.1
	tunnel-mode gre
	tunnel-dev eth0
	tunnel-ttl 255
	address 203.0.113.10/30
	gateway 203.0.113.9

iface eth0
	address 203.0.113.2/30