This is a very minimalistic demonstration of how to setup a VPN-like tunnel. It offers no encryption and is meant solely as a learning excercise.
One of the machines running lametun must have a public IP & will be the designated "server".
The other machine which may behind a NAT must specify the public IP of the server.
./lametun -server 18.104.22.168
The default port is 1234. Make sure to allow the UDP port in your firewall rules or cloud VPCs.