[sip-comm-dev] Quick question regarding ZRTP integration with Sip-communicator.


#1

Hi All,

    I have a quick question. I have sip-communicator running on machine A
and machine B. When I am trying to call B from A, I see that B shows
connected but A shows 'connecting'. I observed that ZRTP Hello packets are
sent only from B to A, and there are no subsequent ZRTP messages from both
sides. Can anyone help me understand this situation? What message triggers
the change from 'Connecting' to 'Connected' status? How is ZRTP involved in
the process?

For some testing purpose, I am intercepting the SIP messages sent back and
forth from A and B, and I change the SDP in any INVITE/ 200 OK message such
that all zrtp-hash attributes are changed to mrtp-hash. Should this mean
that I am disabling ZRTP for both sides? Is there any easier of not using
ZRTP in sip communicator?

I appreciate your time and effort in reading and replying. Since this is an
urgent requirement, I will much appreciate a prompt response.

Thank you and have a great day.

-- SM.


#2

Hi,

ZRTP works only if _both_ clients have a working RTP connection
and have exchanged at least one RTP packet. ZRTP uses a RTP parameter
(RTP SSRC) during its negotiation and needs to "see" this parameter
before it can start the negotiation phase.

Changing the status from "connecting" to "connected" is not part of
ZRTP but IMHO of the SIP state engine. During this state change
SC also manages and open the RTP session and start to send data via
RTP (audi data usually).

Modifying the SDP parameter should not do any harm, it's just an
indicator and ist not used by SC directly. This attribute has a
special meaning if the clients use some additional ZRTP features.

Regards,
Werner

···

Am 19.11.2010 07:03, schrieb SM:

Hi All,

    I have a quick question. I have sip-communicator running on machine A
and machine B. When I am trying to call B from A, I see that B shows
connected but A shows 'connecting'. I observed that ZRTP Hello packets are
sent only from B to A, and there are no subsequent ZRTP messages from both
sides. Can anyone help me understand this situation? What message triggers
the change from 'Connecting' to 'Connected' status? How is ZRTP involved in
the process?

For some testing purpose, I am intercepting the SIP messages sent back and
forth from A and B, and I change the SDP in any INVITE/ 200 OK message such
that all zrtp-hash attributes are changed to mrtp-hash. Should this mean
that I am disabling ZRTP for both sides? Is there any easier of not using
ZRTP in sip communicator?

I appreciate your time and effort in reading and replying. Since this is an
urgent requirement, I will much appreciate a prompt response.

Thank you and have a great day.

-- SM.

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#3

Thank you for replying. Is there any way to disable ZRTP in SC?

--SM.

···

On Fri, Nov 19, 2010 at 12:25 PM, Werner Dittmann < Werner.Dittmann@t-online.de> wrote:

Hi,

ZRTP works only if _both_ clients have a working RTP connection
and have exchanged at least one RTP packet. ZRTP uses a RTP parameter
(RTP SSRC) during its negotiation and needs to "see" this parameter
before it can start the negotiation phase.

Changing the status from "connecting" to "connected" is not part of
ZRTP but IMHO of the SIP state engine. During this state change
SC also manages and open the RTP session and start to send data via
RTP (audi data usually).

Modifying the SDP parameter should not do any harm, it's just an
indicator and ist not used by SC directly. This attribute has a
special meaning if the clients use some additional ZRTP features.

Regards,
Werner

Am 19.11.2010 07:03, schrieb SM:
> Hi All,
>
> I have a quick question. I have sip-communicator running on machine A
> and machine B. When I am trying to call B from A, I see that B shows
> connected but A shows 'connecting'. I observed that ZRTP Hello packets
are
> sent only from B to A, and there are no subsequent ZRTP messages from
both
> sides. Can anyone help me understand this situation? What message
triggers
> the change from 'Connecting' to 'Connected' status? How is ZRTP involved
in
> the process?
>
>
> For some testing purpose, I am intercepting the SIP messages sent back
and
> forth from A and B, and I change the SDP in any INVITE/ 200 OK message
such
> that all zrtp-hash attributes are changed to mrtp-hash. Should this mean
> that I am disabling ZRTP for both sides? Is there any easier of not using
> ZRTP in sip communicator?
>
> I appreciate your time and effort in reading and replying. Since this is
an
> urgent requirement, I will much appreciate a prompt response.
>
>
> Thank you and have a great day.
>
> -- SM.
>

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#4

Sure you can disable ZRTP - please have look at the advanced page of the
SIP account configuration.

Werner

···

Am 19.11.2010 19:45, schrieb SM:

Thank you for replying. Is there any way to disable ZRTP in SC?

--SM.

On Fri, Nov 19, 2010 at 12:25 PM, Werner Dittmann < > Werner.Dittmann@t-online.de> wrote:

Hi,

ZRTP works only if _both_ clients have a working RTP connection
and have exchanged at least one RTP packet. ZRTP uses a RTP parameter
(RTP SSRC) during its negotiation and needs to "see" this parameter
before it can start the negotiation phase.

Changing the status from "connecting" to "connected" is not part of
ZRTP but IMHO of the SIP state engine. During this state change
SC also manages and open the RTP session and start to send data via
RTP (audi data usually).

Modifying the SDP parameter should not do any harm, it's just an
indicator and ist not used by SC directly. This attribute has a
special meaning if the clients use some additional ZRTP features.

Regards,
Werner

Am 19.11.2010 07:03, schrieb SM:

Hi All,

    I have a quick question. I have sip-communicator running on machine A
and machine B. When I am trying to call B from A, I see that B shows
connected but A shows 'connecting'. I observed that ZRTP Hello packets

are

sent only from B to A, and there are no subsequent ZRTP messages from

both

sides. Can anyone help me understand this situation? What message

triggers

the change from 'Connecting' to 'Connected' status? How is ZRTP involved

in

the process?

For some testing purpose, I am intercepting the SIP messages sent back

and

forth from A and B, and I change the SDP in any INVITE/ 200 OK message

such

that all zrtp-hash attributes are changed to mrtp-hash. Should this mean
that I am disabling ZRTP for both sides? Is there any easier of not using
ZRTP in sip communicator?

I appreciate your time and effort in reading and replying. Since this is

an

urgent requirement, I will much appreciate a prompt response.

Thank you and have a great day.

-- SM.

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---------------------------------------------------------------------
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