Re: [rtcweb] I-D Action: draft-hutton-rtcweb-nat-firewall-considerations-00.txt

Hadriel Kaplan <> Tue, 12 March 2013 19:37 UTC

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From: Hadriel Kaplan <>
To: Harald Alvestrand <>
Thread-Topic: [rtcweb] I-D Action: draft-hutton-rtcweb-nat-firewall-considerations-00.txt
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Subject: Re: [rtcweb] I-D Action: draft-hutton-rtcweb-nat-firewall-considerations-00.txt
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On Mar 11, 2013, at 1:29 PM, Harald Alvestrand <> wrote:

> On 03/11/2013 06:04 PM, Reinaldo Penno (repenno) wrote:
>> Hello,
>> Why not use Port Control Protocol (PCP) to control Firewalls and NATs
>> explicitly?
> We can switch to that as soon as 100% of firewalls support it - until then, we have to be able to rely on other techniques.

Not to contradict with your point, but to pile on it...
Even if 100% of the Firewalls were to support PCP, you'd still want to do STUN/TURN/ICE methinks, because 

1) you never know that your local Firewall is the *only* Firewall-ish thing between you and the public Internet or some network reachable by both parties.  This problem already happens with UPnP and NAT-PMP today, and has been noted before in BEHAVE or MMUSIC, I think. 

2) There's a big difference between 100% of Firewalls implementing PCP, and it being actually enabled/turned-on in 100% of them.

3) you don't know if the IP path across the Internet works for a given address family - this has been given as the reason STUN/ICE needs to be required for v4/v6 dual-stack implementations, to test reachability across the IPv6 Internet before trying to use it; regardless of NATs/Firewalls.