NAT & CGNAT Improvements

[SomeoneWeird]

Improvement Suggestion

There has been a notice recently that globally a lot of carriers are migrating their users to CGNAT.

This leads to an issue where, because Dogecoin Core (and other pups, such as dogenet) require P2P direct access, they no longer function as intended, even when the user is successfully port forwarding to their Dogebox.

This improvement discussion is twofold, how can we improve detection & messaging, and how can we try and mediate this issue (we cannot "fix it").

Detection & Messaging

• We should figure out if we can detect CGNAT, and show warnings.

  • Per RFC, CGNAT addresses are in known IP ranges, though these may only be accessible via the users router.

• We can run something on our infra somewhere that lets the Dogebox do a "is my port open" challenge.

  • This will allow us to "confirm" if the user has correctly port-forwarded. Perhaps something we do every 24h on all host-exposed pup ports?

Mediation

• Support for running Tor has been floated on Discord, and while this may "fix" some issues for people behind CGNAT, it would only do so for other folks running Tor. There is also a generally agreed negative consensus of thought where it comes to running Tor. Something to consider.

• We should look at adding proper UPNP support, even though as a security person I always immediately disable this on my routers :)