Possibly silly question: I was under the impression that only TCP allowed for NA...

wmf · on April 17, 2015

NAT traversal is easier with UDP than with TCP. Here's a good article on the topic: https://www.zerotier.com/blog/?p=226

manigandham · on April 18, 2015

Thanks for posting, that was a nice article but the intro to ZeroTier was even better, pretty cool software.

gliptic · on April 17, 2015

NAT traversal isn't necessary when you send packets out of your network, be they TCP or UDP. That's standard operation for NATs.

JoeAltmaier · on April 17, 2015

However routers often have an 'allow UDP' checkbox. UDP can be globally disabled, or enabled only for certain ports. uPNP can mitigate this, but most of us have that turned off to prevent Trojan horses from opening the gates entirely.

nomel · on April 17, 2015

Bigger question is, why in the world does your router disable UDP by default!?

Things like games and video streams are almost universally UDP, because it's better to forget about the data than stop everything, and go get your lost packet.

stephen_g · on April 17, 2015

Not to mention DNS. Presumably the router would have a DNS caching server that could get around the block, but you wouldn't be able to have a computer use any other DNS server...