How does a TURN server send data to peers behind a NAT?


2 weeks ago


3 time


I understand in TURN there is a client, a TURN server, and peer(s). The client itself creates an Allocation on the TURN server, after which a relayed transport address is returned back to the client in order to send data to one or many peers.

I understand how the client can get around its NAT, however I didn't see anything in the RFC5766 about how the peers themselves are able to accept the UDP through their NAT's from the TURN server (otherwise through TURN or not, it would be unsolicited UDP). The peers would have to reach out to the TURN server first.

Is there a step I'm missing? Is the relayed transport address sent to the peer so that UDP hole punching can begin before communication can flow between the TURN Server and its peer(s)?

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