Re: [rtcweb] STUN for keep-alive

Eric Rescorla <ekr@rtfm.com> Fri, 16 September 2011 18:28 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 16 Sep 2011 11:30:46 -0700
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To: Dan Wing <dwing@cisco.com>
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Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] STUN for keep-alive
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On Fri, Sep 16, 2011 at 11:07 AM, Dan Wing <dwing@cisco.com> wrote:
>> -----Original Message-----
>> From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On
>> Behalf Of Eric Rescorla
>> Sent: Wednesday, September 14, 2011 10:32 AM
>> To: Christer Holmberg
>> Cc: rtcweb@ietf.org
>> Subject: Re: [rtcweb] STUN for keep-alive
>>
>> On Wed, Sep 14, 2011 at 10:20 AM, Christer Holmberg
>> <christer.holmberg@ericsson.com> wrote:
>> >
>> > Hi,
>> >
>> >>One new concern in this context is maintaining the consent freshness.
>> >>The browser needs to be sure that the recipient of traffic is stil
>> responding in a way that can't be forged. It's likely RTCP provides
>> this (though we'd need to analyze to be sure) but perhaps better would
>> be to mandate STUN checks
>> >>at enough frequency that you get some sort of level of freshness....
>> maybe every 2 minutes or something.
>> >
>> > Please note that the STUN keep-alives are implemented using STUN
>> indication messages, so there are no replies (nor does the receiver
>> perform an authentication check).
>>
>>
>> Oh... I had forgotten that.... that's not good.
>
> The RTCP receiver reports should be adequate for 'consent freshness', no?
> If I still like receiving the traffic, I'll report that I'm receiving it.
> If I have crashed or disconnected or am not listening on that port, I won't.

I believe so, though I'd have to make sure there's enough entropy. And of course
some implementations may not do RTCP...

-Ekr