Working with servers behind a NAT or on a local network (aka "p2p")

[pthatcher]

I've having an increasing number of people asking me for a "p2p" solution for WebTransport. As I've investigated why, and I have found that some people want to run a client/server pair on a common network (where using mDNS for discovery, like WebRTC does, could make sense), and others are running a server behind a NAT, and the easiest solution for them is to use p2p tech like ICE, but other NAT traversal technique may work (for example NAT-PMP or UPnP).

Meanwhile, there is a lot of discussion in the IETF about NAT traversal and p2p QUIC, even without ICE.

What should our approach be for WebTransport on these fronts that are "p2p"?

[jan-ivar]

Meeting:

• Is this addressed by serverCertificates API? If your use case is you have a server on LAN with custom cert.
• Seems half of the solution at least
• Other half is the network part: With WebRTC you can do mDNS discovery.
• Could WebRTC (or new IceTransport) be used to bootstrap a WebTransport connection?
• Exposing mDNS to actual IPs would be a fingerprinting leak
• Cleaner way would be to separate out IceTransport

[jan-ivar]

I wonder are mDNS addresses extracted from WebRTC usable in other web platform APIs already? If user agents support this already then could this be polyfilled?