[Cryptography] peering through NAT

[Jeremy Stanley]

On 2019-05-09 21:45:14 +1000 (+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?

You're probably looking for the IGD (Internet Gateway Device)
protocol commonly implemented via UPnP (ISO/IEC 29341 a.k.a.
Universal Plug-n-Play) in popular consumer routing devices for well
over a decade.

> What happens if there are two machines both running bitcoin core
> behind the nat?

Couldn't tell ya, never touched the stuff.
-- 
Jeremy Stanley
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