[mtud]

Without TURN, two clients that want to do streaming communication connect directly to each other, letting both ends know things like IP addresses, supported protocols, and other fingerprintable features. This was the norm for a long time - “I got your IP, I know where you live”

[markisus]

I’m not sure what you mean by fingerprinting and supported protocols. None of that would be present inherently in a UDP stream unless the application included it. As for hiding IP address, that is a valid use case for a TURN server but I’m guessing 99% of TURN server usage occurs only because the NAT hole punch failed.

[VWWHFSfQ]

> by fingerprinting and supported protocols. None of that would be present inherently in a UDP stream unless the application included it.

Much like TLS, both clients offer all the protocols, versions, and media encodings that they support so that they can find a common set that they can use together.

This is standard negotiation when establishing connections in WebRTC and it's obviously fingerprintable information.