esrrhs/spp ? reverse-engineered prompt

Build me a simple but powerful Go proxy tool like the one in this repo.

I want a single command line app that can run as a server and as different kinds of clients, so I can do normal forwarding, reverse proxying, and SOCKS5 forwarding or reverse SOCKS5. It should let me expose local services through a remote server, or reach a local service from the server side, and it should support both TCP and UDP style traffic. If possible, include the more advanced tunnel options too, like reliable UDP, reliable ICMP, HTTP based tunneling, KCP, and QUIC, and make it easy to mix the outer proxy protocol and the inner transport protocol.

Please make it easy to run from the terminal and with Docker too. A couple of clear example commands in the README would be great, so I can quickly start a server and connect a client. If you need to check current docs for any of the tunnel protocols, go ahead and look them up online.