[SIP Beyond VoIP] Some progress: Getting started with sylkserver (and NAT)

Adrian Georgescu ag at ag-projects.com
Mon Jan 4 15:16:49 CET 2016

The issue is your middleman proxy. I cannot speculate what and how it does its thing.


> On 04 Jan 2016, at 13:07, Adrian Weiler <sylk-testing at aweiler.com> wrote:
> Hi,
> thank you for your response.
> At 04.01.2016 01:23 Adrian Georgescu wrote:
>> MSRP is another type of media, like RTP media which is used for audio/video.
>> If SylkServer is sitting on a public IP, MSRP media should just work as the server is always reachable by an MSRP client.
>> Short hint, enable logging and see what happens, each protocol can be debugged to a file logged by SylkServer.
> I already did that, but wanted to avoid posting tons of logs to this
> public space.
> What I did: on a Blink client, I select my conference and hit the "Chat"
> button. The chat window opens, then I click "Connect". Then Sylkserver
> receives an INVITE, sends 100 Trying, then 200 OK. Then Sylkserver
> receives the client's ACK. But then nothing happen. After 15 seconds,
> the client becomes impatient and disconnects.
> Observations:
> - If I do the same on a test conference at sip2sip.info, I receive a
> greeting (Conference Room. Welcome to Sylkserver! etc...). On my own
> conference, I don't receive such a greeting.
> - When opening a conference with sip2sip.info the client's SIP trace
> differs after sending ACK: The client now sends SUBSCRIBE. On my own
> conference, the client just waits.
> It seems that for some reason the client doesn't understand that there
> is a conference to subscribe to.
> - When talking to sip2sip.info, the client is *much* more verbose. When
> connecting to my own conference, the client's INVITE is packet #18. When
> connecting to sip2sip.info, that INVITE is packet #70. When talking to
> sip2sip.info, the clients SUBSCRIBEs to username+presence, and to
> username+dialog. With my own conference, there are no such subscription
> requests. Is there anything to configure here? This could also be
> related to the following observation:
> - When Blink PUBLISHes "Event: presence", my server's response is "480
> Temporarily Unavailable" and contains a header line "Server: repro
> 1.10.0". So this comes from the proxy, not from SylkServer. The question
> here is: is reSIProcate OK as proxy? (I have described my setup in the
> original post).
> - For some reason, the server also sends a SUBSCRIBE back to the client.
> This seems wrong, and the client replies to this with "482 Loop
> Detected". I haven't yet been able to figure out why this happens, but
> it doesn't seem to originate from SylkServer. At least I could not find
> it in SylkServer's SIP trace. So it must be the proxy again. However
> this happens also with voice-only conferences, which do work.
> Is that enough hinformation? On the server side, I can provide
> sip_trace.log, core_trace.log and notifications_trace.log. I have also
> enabled traces on the client side (msrp_trace.txt,
> notifications_trace.txt, pjsip_trace.txt, and sip_trace.txt). As far as
> the communication with SylkServer is concerned, the client's SIP trace
> contains the same packets as the server. The msrp_trace.txt contains
> just a single line for the failed conference: "Connecting to". I tried
> MSRP with and without TLS (on both sides of the connection ;-). Always
> the same.
> Best regards,
> Adrian Weiler
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