I recently uploaded a video explaining port forwarding, or port tunnelling as I like to call it. This is a technique that allows you to remotely connect to TCP ports that would not normally allow inbound remote connections (either due to firewall or the way the listener is configured).

EDIT: A few people have asked for my PT.exe program, so here’s a download link (needs more testing and optimising really, so maybe treat this as a BETA version) : https://github.com/VbScrub/PortTunnel

You can see how to use it, and how it works, in the video below