Need assistance with TCP Reverse connection

I am creating an authentication server for some projects I'm working on. This authentication server works by receiving and transmitting data to users trying to authenticate. The user can send data to the server succesfully but when sending back it requires port forw开发者_运维百科arding. I read a way that I would not require port forwarding by using reverse connection but I have no idea how to get it working. I found a tutorial and tried to implement but when it tries to connect to read the stream it says the connection is refused.

Any ideas?

If the user is already connecting to the server, why not just keep the (existing) connection open, and use that for bidirectional communication?

I can see no reason to open a second connection from the server back to the client.