Re: [BEHAVE] [rtcweb] FW: New Version Notification for draft-chenxin-behave-turn-websocket-00.txt

["Chenxin (Xin)" <[e-mail]>]

>-----Original Message-----
>From: Hutton, Andrew [mailto:[e-mail]]
>Sent: Thursday, May 16, 2013 4:28 PM
>To: Bernard Aboba; Chenxin (Xin); [e-mail]; [e-mail]
>Subject: RE: [rtcweb] FW: New Version Notification for
>draft-chenxin-behave-turn-websocket-00.txt
>
>I agree with Bernard's comments regarding the impact of DPI but of course such
>DPI devices do what they do and we can't and even don't want to stop them
>from doing it. However for the case when policy is such that the firewall will only
>allow traffic to traverse that comes from the HTTP Proxy or a network specific
>TURN server and there is no deliberate policy to block WebRTC media we need a
>solution and this is what draft-hutton-rtcweb-nat-firewall-considerations-00
>addresses.
>


Yes, we could not stop the use of DPI, but we should consider this scene. I think that is the purpose of F37. Besides, websocket is friendly to http proxy too. I agree that draft-hutton-rtcweb-nat-firewall-considerations-00 should be a baseline to solve the traverse problem of nat and fireward. But I think the turn over websocket solution should also be considered as a option to solve some corner use case and requirement.

Best Regards,
     Xin 

>So far I don't see the benefit that TURN over websockets would have in this
>scenario and it needs additional implementation in the browser and the TURN
>server.
>
>Regards
>Andy
>
>
>> -----Original Message-----
>> From: Bernard Aboba [mailto:[e-mail]]
>> Sent: 15 May 2013 18:20
>> To: Hutton, Andrew; Chenxin (Xin); [e-mail]; [e-mail]
>> Subject: RE: [rtcweb] FW: New Version Notification for draft-chenxin-
>> behave-turn-websocket-00.txt
>>
>> Andrew Hutton said:
>> > When we wrote the draft http://tools.ietf.org/html/draft-hutton-
>> rtcweb-nat-firewall-considerations-00 we did not include this option
>> because we did not see the benefit of additional transport options for
>> TURN given that the existing options (E.g. TURN/TCP and TURN/TLS) seem
>> to be meet our needs.
>> >
>> > So what would be the benefits that justify this addition transport
>> option for TURN?
>>
>> [BA] In my experience,  institutions with very restrictive security
>> policies (e.g. those that don't allow UDP in or out) also tend to
>> deploy other measures such as deep packet inspection.   So just because
>> some traffic is allowed in or out on port 80 does not mean that
>> TURN/TCP will be allowed on that port - a DPI box may examine the
>> traffic and complain if it doesn't see HTTP being used.  On the other
>> hand, unless the DPI box is upgraded, it will also complain about
>> websockets.  So I think draft-chenxin only helps in a situation where
>> TURN over Websockets would be allowed when TURN/TCP would not
>be.  That
>> scenario is rare, at least at the moment.
>>
>> The argument for TURN over Websocket/TLS is even more difficult to
>> make. While DPI boxes may examine traffic destined to port 443
>> carefully to make sure that TLS is really being used,  assuming that
>> the DPI box does not see anything it considers fishy, the TLS exchange
>> will complete and the DPI box will lose visibility.  After TLS is
>> running, the DPI box does not have much information available to
>> distinguish TURN/TLS from HTTP over TLS, with or without websockets --
>> and those things it does have (such as packet size) are as likely to
>> result in an objection to websocket transport as TURN/TLS.  So I'm not
>> sure that draft-chenxin will help in that situation either.
>
>
>