[Freeswitch-users] problems with freeswitch + zrtp in proxy-media mode
peter.kosztolanyi at gmail.com
Sat Feb 2 21:08:33 MSK 2013
Hi, I have exactly the same problem as Eli described below. Eli, I'm glad
too that finally not I'm the only guy in this situation.
In my case the proxy media mode is required for end-to-end security but
bypass-media is not an option because the endpoints are in different
The normal media handling mode (not proxy and not bypass) works well
however in this case there are different SAS on the two endpoints. Probably
it's normal because FS opens a new session and the first SAS is not
transferred to the other side automatically.
But what I'm more interested in what "inbound-zrtp-passthru" is actually
doing? I couldn't find proper docs only the codebase at
I can see two entries in my logs relating to this:
2013-02-02 18:26:14.925953 [DEBUG] mod_sofia.c:5031 [zrtp_passthru]
Setting a-leg inherit_codec=true
2013-02-02 18:26:14.925953 [DEBUG] mod_sofia.c:5034 [zrtp_passthru]
Setting b-leg absolute_codec_string='PCMU at 8000h@20i at 64000b'
Meanwhile someone on the linphone dev mailing list said that linphone does
not support "zrtp-hash" attribute in SIP/SDP. May it has any effect in FS
media proxy with zrtp?
On Fri, Feb 1, 2013 at 9:33 PM, Steven Ayre <steveayre at gmail.com> wrote:
> Is there a reason you're using proxy media mode?
> Does it work in normal media handling mode? (ie not proxy and not bypass)
> On 1 February 2013 14:15, Eli Burke <eburke at edge-net.net> wrote:
>> Yes, inbound-zrtp-passthru is true. I think it gets set automatically
>> when you turn on ZRTP.
>> The config I'm testing with is a stock 'enable_zrtp=yes' build of HEAD
>> circa last week, with proxy-media=true added to Local_Extension in the
>> default dial plan.
>> On Feb 1, 2013, at 6:00 AM, royj at yandex.ru wrote:
>> > Is there <param name="inbound-zrtp-passthru" value="true"/> in profile
>> > On Thu, 31 Jan 2013 17:43:34 -0500
>> > Eli Burke <eburke at edge-net.net> wrote:
>> >> I'm trying to use Freeswitch with an open source voip client called
>> Linphone, but cannot manage to establish functioning ZRTP sessions. The
>> problem *seems* to be related to the RTP stream's SSRC. I'm trying to
>> conclusively determine if the problem lies with Linphone, Freeswitch, or
>> one of the underlying zrtp implementations (libzrtp and zrtpcpp).
>> >> Here's what I've determined so far:
>> >> 1) ZRTP support is compiled and functioning. I can establish ZRTP
>> sessions between two iPhones running Groundwire.
>> >> 2) linphone + ZRTP works correctly if I make a one legged call to a
>> Freeswitch echo extension
>> >> 3) linphone + ZRTP works correctly if I turn on bypass-media
>> >> 4) linphone gets a CRC error when trying to verify the ZRTP packet on
>> any two-legged call
>> >> 5) disabling the CRC check results in a successful ZRTP session, but
>> the audio is extremely garbled
>> >> Is Freeswitch modifying the ZRTP packets when running in proxy mode?
>> If so, how is it that some clients are able to handle this situation?
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> Official FreeSWITCH Sites
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> Official FreeSWITCH Sites
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
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