[Cryptography] peering through NAT

[Ángel]

On 2019-05-09 at 21:45 +1000, jamesd at echeque.com wrote:
> NAT makes it hard to contact a computer behind nat, but Bitcoin core has 
> no problems with most nats, even when behind multiple levels of nats.
> 
> It does something to tell the nat to direct incoming messages on port 
> 8333 to it, without the end user usually needing to manually set up port 
> forwarding.
> 
> What is the protocol to tell a nat to forward incoming messages?
> 
> What happens if there are two machines both running bitcoin core behind 
> the nat?

UPnP ?

https://en.wikipedia.org/wiki/Universal_Plug_and_Play#NAT_traversal
https://en.wikipedia.org/wiki/Internet_Gateway_Device_Protocol

Now, what does NAT traversal have to do with crypto?

And how is this question related to the “NIST announced Round 1
candidates for lightweight crypto competition” thread to which you
replied (albeit with a different subject)?

Regards