nat-birthday-paradox

If your NAT allows arbitrary connections out, and you're patient enough, you can probably finagle a peer to peer connection, eventually. Here's a discussion about that [1]. But that math is based on each NAT having a single external address; if your NAT spreads you over multiple addresses, the math gets much worse. And there's a lot of other considerations; chances are your NAT won't be happy if you send all those probe packets at once, and your user may not be either. It's probably only worth it to do exhaustive probing if the connection is long lived, and proxying is expensive (in dollars because of bandwidth or in latency) [1] https://github.com/danderson/nat-birthday-paradox/tree/maste...