How to forward the port to the server?

Question

C++ / C#

The task is as follows, it is necessary to forward the port from the client (gray ip) to the server (white ip), is it possible to create a connection from the client to the server with a simple socket and proxy traffic to the required port on the client side (in theory everything sounds OK, in practice what problems can with this)? And if anyone knows ready-made solutions, I would not mind learning VPN and SSH -R not to offer, I have already heard about them, I would just like to create my own independent solution

Answer 1

It's just that the client behind nat must be the initiator of the connection. Type it opens connection and in it already waits for a command from the server.
Well, the "transport" of commands - to taste from single packets (responses will arrive via nat) to a persistent line of any type ... Though soap.