Re: [rtcweb] STUN for keep-alive

Harald Alvestrand <harald@alvestrand.no> Sun, 18 September 2011 21:08 UTC

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Date: Sun, 18 Sep 2011 23:10:34 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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To: Eric Rescorla <ekr@rtfm.com>
References: <7F2072F1E0DE894DA4B517B93C6A05852233EDB21D@ESESSCMS0356.eemea.ericsson.se> <1D062974A4845E4D8A343C653804920206648CB0@XMB-BGL-414.cisco.com> <7F2072F1E0DE894DA4B517B93C6A05852233EDB264@ESESSCMS0356.eemea.ericsson.se> <1D062974A4845E4D8A343C653804920206648CEB@XMB-BGL-414.cisco.com> <7F2072F1E0DE894DA4B517B93C6A05852233EDB2F0@ESESSCMS0356.eemea.ericsson.se> <1D062974A4845E4D8A343C653804920206648D0F@XMB-BGL-414.cisco.com> <7F2072F1E0DE894DA4B517B93C6A05852233EDB3E5@ESESSCMS0356.eemea.ericsson.se> <4E70D2E6.1000809@alvestrand.no> <CABcZeBORi5NLSsztnMfkwL43p9oKG9mi6e1WWOaiafAO_DpTVg@mail.gmail.com> <7F2072F1E0DE894DA4B517B93C6A05852233D45FA3@ESESSCMS0356.eemea.ericsson.se> <CABcZeBO9hUSYZhLrcfbaK9HLGXq-q1EvqWOy6-gAN5xom6Z2-A@mail.gmail.com> <092401cc749b$8fd64940$af82dbc0$@com> <CABcZeBPgRD6kb2gg=m9NckSa1wrzwzJS6527nYqFG34b0cjfgQ@mail.gmail.com>
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Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] STUN for keep-alive
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On 09/16/2011 08:30 PM, Eric Rescorla wrote:
> 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...
Depending on RTCP seems less uncomfortable with SRTP than with plaintext 
RTCP.
I don't think we want to support RTCP-less applicaitons; if saying "no" 
to them helps them not occur (it doesn't always help...)