Whitepaper for NAT traversal improvements

[introspection3]

https://tailscale.com/blog/how-nat-traversal-works

[hamishcoleman]

Thanks for the link. There have been a number of NAT traversal improvements demonstrated since the original n2n paper, and n3n could definitely benefit from adding this technique.

One of the other contributors was testing some improvements like this a couple of years ago, so maybe that work can be restarted with hints from articles like this one.

I personally think that the core code needs some improvements to clearly separate the various protocol phases first - currently trying to layer on better NAT traversal runs the risk of accidentally changing the protocol, and is relatively difficult to switch in multiple different techniques for easy testing.

[introspection3]

Thank you, I'm looking forward to it