On our last post about UDP hole-punching we learned how we could use UDP traffic to exploit the stateful nature of firewalls, thus bypassing blocks for incoming connections. That was a fun exercise, but of limited use in the real world. On this post we’re going to turn it

This post was originally published in 2018 Intro UDP hole punching is a widely documented firewall bypass technique. It doesn’t exploit any bugs or flaws, it does exploit UDP’s sessionless nature and firewalls’ stateful nature. The technique relies on the fact that in a UDP conversation there is