[Galene] Re: coturn config

[Juliusz Chroboczek <jch@irif.fr>]

>> More about my context: I just put a coturn in place for my synapse
>> server and it's working. I would like to use the same one in place for
>> a future galene but I don't know if the secret for the API is in
>> conflict with the user/password needed for galene.

> According to what Toke explained to me, Cell is referring to this protocol:

>   https://tools.ietf.org/html/draft-uberti-behave-turn-rest-00

I've now read this document a second time, and I still don't get it.
Could somebody please explain the purpose of this protocol?

In normal TURN, there is a username/password key that must be known by the
WebRTC peers.  That's well known to be insecure, but it only protects
access to the TURN server, so the only bad thing that could happen is that
the TURN server will be used by other services.

With the REST API, we introduce an extra web server.  The web server and
the TURN server somehow coordinate to generate ephemeral passwords (for
a very lax notion of ephemeral -- the draft recommends 86400 seconds)
which are communicated over HTTP to the WebRTC peers.

The TURN credentials are now being rotated periodically, granted, but an
attacker can simply contact the web server to find out what they are.
We're adding an extra point of failure, but I don't see what we are gaining.

What am I missing?

-- Juliusz