Re: [rtcweb] consent freshness [was RE: STUN for keep-alive]
Magnus Westerlund <magnus.westerlund@ericsson.com> Mon, 19 September 2011 15:33 UTC
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Date: Mon, 19 Sep 2011 17:35:23 +0200
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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To: Dan Wing <dwing@cisco.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> <4E765E4A.3050801@alvestrand.no> <0ced01cc76de$28731630$79594290$@com>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] consent freshness [was RE: STUN for keep-alive]
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On 2011-09-19 17:09, Dan Wing wrote: >> -----Original Message----- >> From: Harald Alvestrand [mailto:harald@alvestrand.no] >> Sent: Sunday, September 18, 2011 2:11 PM >> To: Eric Rescorla >> Cc: Dan Wing; rtcweb@ietf.org >> Subject: Re: [rtcweb] STUN for keep-alive >> >> 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...) > > (Case in point: RTCP has long been a requirement for RTP, but > implementation was still skipped by Cisco, and probably others.) > > I don't know how much entropy Eric was looking for. RTCP receiver > reports only echo back the SSRC, which is 32 bits and is going to > be static for the duration of each RTP session (yes, SSRC collision > could make it change. But that is atypical.) STUN request/response > echoes back the 96-bit transaction id, which changes as often as the > requestor likes (typically each new STUN transaction). As I wrote in http://www.ietf.org/mail-archive/web/rtcweb/current/msg01327.html The amount of entropy in an RTCP message may be as low as 8 bits. If certain restrictions is accepted then we can probably reach 20-24 bits without requiring more than basic RTCP provides. > > Which would someone skip -- skip sending/implementing RTCP for > consent freshness, or skip sending/implementing STUN request/response > for consent freshness? The STUN request/response is also additional > data, whereas RTCP is something that is "already being sent" (thus > the consent freshness isn't adding more bits on the wire). I think RTCP may work for consent freshness. A longer series of consistent RTCP messages to maintain the consent seems reasonable, despite the low number of entropy bits per actual message. But, I do think RTCP might have to few bits for the initial check where one wants a rapid indication that it is fine to send media at higher bit-rates. Cheers Magnus Westerlund ---------------------------------------------------------------------- Multimedia Technologies, Ericsson Research EAB/TVM ---------------------------------------------------------------------- Ericsson AB | Phone +46 10 7148287 Färögatan 6 | Mobile +46 73 0949079 SE-164 80 Stockholm, Sweden| mailto: magnus.westerlund@ericsson.com ----------------------------------------------------------------------
- [rtcweb] STUN for keep-alive Christer Holmberg
- Re: [rtcweb] STUN for keep-alive Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] STUN for keep-alive Christer Holmberg
- Re: [rtcweb] STUN for keep-alive Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] STUN for keep-alive Christer Holmberg
- Re: [rtcweb] STUN for keep-alive Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] STUN for keep-alive Christer Holmberg
- Re: [rtcweb] STUN for keep-alive Jonathan Lennox
- Re: [rtcweb] STUN for keep-alive Randell Jesup
- Re: [rtcweb] STUN for keep-alive sisalem
- Re: [rtcweb] STUN for keep-alive Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive Harald Alvestrand
- Re: [rtcweb] STUN for keep-alive Eric Rescorla
- Re: [rtcweb] STUN for keep-alive Christer Holmberg
- Re: [rtcweb] STUN for keep-alive Göran Eriksson AP
- Re: [rtcweb] STUN for keep-alive Eric Rescorla
- Re: [rtcweb] STUN for keep-alive Dan Wing
- Re: [rtcweb] STUN for keep-alive Dan Wing
- Re: [rtcweb] STUN for keep-alive Dzonatas Sol
- Re: [rtcweb] STUN for keep-alive Eric Rescorla
- Re: [rtcweb] STUN for keep-alive Dan Wing
- Re: [rtcweb] STUN for keep-alive Dzonatas Sol
- Re: [rtcweb] STUN for keep-alive Harald Alvestrand
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Olle E. Johansson
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Olle E. Johansson
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive Magnus Westerlund
- [rtcweb] consent freshness [was RE: STUN for keep… Dan Wing
- Re: [rtcweb] consent freshness [was RE: STUN for … Magnus Westerlund
- Re: [rtcweb] consent freshness [was RE: STUN for … Dan Wing
- Re: [rtcweb] consent freshness [was RE: STUN for … Eric Rescorla
- Re: [rtcweb] consent freshness [was RE: STUN for … Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] STUN for keep-alive Randell Jesup
- Re: [rtcweb] consent freshness [was RE: STUN for … Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Colin Perkins
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Colin Perkins
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] consent freshness [was RE: STUN for … Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] consent freshness [was RE: STUN for … Magnus Westerlund
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] consent freshness [was RE: STUN for … Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] consent freshness [was RE: STUN for … Randell Jesup
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Magnus Westerlund
- Re: [rtcweb] consent freshness [was RE: STUN for … Magnus Westerlund
- Re: [rtcweb] consent freshness [was RE: STUN for … Randell Jesup
- Re: [rtcweb] STUN for keep-alive Cullen Jennings
- Re: [rtcweb] STUN for keep-alive Michael Tüxen
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Hadriel Kaplan
- Re: [rtcweb] consent freshness [was RE: STUN for … Magnus Westerlund
- Re: [rtcweb] consent freshness [was RE: STUN for … Harald Alvestrand
- Re: [rtcweb] consent freshness [was RE: STUN for … Stefan Håkansson LK
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Olle E. Johansson
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Harald Alvestrand
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Harald Alvestrand
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Harald Alvestrand
- Re: [rtcweb] STUN for keep-alive - RTCP-less appl… Iñaki Baz Castillo