I can not find any information on how TUN/TAP works. I would like to create a simple tunnel between two hosts and establish a virtual address space between them (similar to a GRE tunnel). I do not want any encryption, or any VPN.
My issue is that I don't even know what protocol TUN speaks. When a tunnel interface is created and data is sent to the other end what protocol is the listening "tun server" (tunnel endpoint) speaking and what port are you connecting to?