Re: [rtcweb] Importance of local addresses in ICE

Are you referring to our proposal where we surface the single host IP used
for contacting the STUN/TURN servers, or surfacing all host IPs? I
generally agree that surfacing a single host IP is important, especially
given CGN as you mention, but surfacing all may have fingerprinting
implications.

It would be good to get empirical data on how often host-host occurs in the
wild - if anyone is running a WebRTC service with p2p calls and can get
data on the %age of host-host candidate calls, that would be greatly
appreciated. (Hangouts is client-server.)

On Sun, Apr 26, 2015 at 8:24 PM, Cullen Jennings <fluffy@iii.ca> wrote:

> There has been some suggestion that the ICE should not advertise
> candidates that were addresses from a NATed address space. I think it is
> critical that we do and here is why.
>
> Carrier Grade NATs (CGN) are becoming far more common in many countries.
> Most measures of them show they are not friendly towards over the top VoIP
> traffic (totally shocker given they are often deployed by people offering a
> commercial voice service as well). So when you have two user both behind
> the same GCN, if ICE does not expose the local address, all of the traffic
> is forced thought the GCN (which may have more jitter than you might hope)
> and to a TURN server. If the ICE contained the local candidates then media
> would go directly through between the devices.
>
> CGN while not that common in the US is prevalent in many countries -
> particularly ones that had less IPv4 addressed allocated to them.
>
> Now you can say that this might reveal some information about their IP
> address. But think about what we really wish the wold looked like. There
> was no NAT and they had a IPv6 address. I have a hard time seeing how to
> DHCP generated address behind the NAT is hugely different than a random
> allocated v6 address so I don't see much downside on doing this and I see
> huge upside - particularly for people that are working of a cellular data
> link behind a CGN.
>
> I am also think that in general, end to end is better for privacy than
> forcing all your data through a MITM that the user does not control (the
> TURN server and CGN in this case).
>
>
>
>
>
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