[Freeswitch-dev] Debugging DTLS for WebRTC

Anthony Minessale anthony.minessale at gmail.com
Wed Sep 25 03:18:05 MSD 2013


I already told you about the constraints bit in the last email. =D




On Tue, Sep 24, 2013 at 6:05 PM, Sam Russell <sam.h.russell at gmail.com>wrote:

> Thanks Anthony.
>
> For future reference, Chrome has DTLS disabled by default, so in JsSIP
> (check their source for how to clone your own full copy and hack on it) you
> just need to override this bit in js/gui.js
>
> RTCConstraints: {"optional": [{'DtlsSrtpKeyAgreement': 'true'}]} // change
> true to false
>
> After this, it only uses FreeSwitch's key, and you can then decrypt the
> handshake correctly in Wireshark - but it looks like Wireshark won't let
> you decode SRTP (it doesn't seem to handle the 0x80->RTCP muxing in the
> DTLS packets, and it won't let you choose SRTP as the inner protocol) -
> screenshot shows the output I get from wireshark 1.10.2 -
> http://i.imgur.com/NyVHAdy.png
>
> Am I being a bit silly here, or does wireshark not yet have the capability
> to decode SRTP in DTLS?
>
> Cheers
> Sam
>
>
> On Wed, Sep 25, 2013 at 3:07 AM, Anthony Minessale <
> anthony.minessale at gmail.com> wrote:
>
>> They generate them iirc.
>> There is a constraints field in the javascript that tells if you want to
>> use dtls or not.
>> Have you tried it with jssip?
>>
>>
>>
>> On Tue, Sep 24, 2013 at 5:00 AM, Sam Russell <sam.h.russell at gmail.com>wrote:
>>
>>> Hi,
>>>
>>> I've spent a few hours digging through captures and RFCs and I think I
>>> found where I'm getting caught - having the server key isn't enough - you
>>> need the client key (i.e. from your browser). I've got a couple of issues
>>> I'm tracking down with WebRTC support for FreeSwitch, does anybody know how
>>> to export private keys from Chrome/Firefox that they use for WebRTC? If I
>>> can get the browser private key AND the key from Freeswitch (dtls-srtp.key
>>> by the looks) then I can decrypt a DTLS stream and figure out what's going
>>> on.
>>>
>>> Cheers
>>> Sam
>>>
>>> _________________________________________________________________________
>>> Professional FreeSWITCH Consulting Services:
>>> consulting at freeswitch.org
>>> http://www.freeswitchsolutions.com
>>>
>>> 
>>> 
>>>
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>>>
>>>
>>
>>
>> --
>> Anthony Minessale II
>>
>> FreeSWITCH http://www.freeswitch.org/
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>>
>> AIM: anthm
>> MSN:anthony_minessale at hotmail.com
>> GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com
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>>
>> FreeSWITCH Developer Conference
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>> googletalk:conf+888 at conference.freeswitch.org
>> pstn:+19193869900
>>
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>>
>> 
>> 
>>
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://wiki.freeswitch.org
>> http://www.cluecon.com
>>
>> FreeSWITCH-dev mailing list
>> FreeSWITCH-dev at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev
>> http://www.freeswitch.org
>>
>>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> 
> 
>
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
>
> FreeSWITCH-dev mailing list
> FreeSWITCH-dev at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev
> http://www.freeswitch.org
>
>


-- 
Anthony Minessale II

FreeSWITCH http://www.freeswitch.org/
ClueCon http://www.cluecon.com/
Twitter: http://twitter.com/FreeSWITCH_wire

AIM: anthm
MSN:anthony_minessale at hotmail.com
GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com
IRC: irc.freenode.net #freeswitch

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