GRE tunnel between two linux boxes

host1 - 10.x.y.h1

ip tunnel add interfacegre3 mode gre remote 10.x.y.h2 local 10.x.y.h1
ip addr add 10.0.30.1 dev interfacegre3
ip link set interfacegre3 up
ip route add 10.0.40.0/24 dev interfacegre3
ifconfig interfacegre up

host2 - 10.x.y.h2
ip tunnel add interfacegre4 mode gre remote 10.x.y.h1 local 10.x.y.h2
ip addr add 10.0.40.1 dev interfacegre4
ip link set interfacegre4 up
ip route add 10.0.30.0/24 dev interfacegre4
ifconfig interfacegre up

# use this only to remove the greinterface
ifconfig interfacegre down
ip link set interfacegre down
ip tunnel del interfacegre