[SIP Beyond VoIP] Sylkserver Setup without a SIP proxy

[Valentin Kleibel]

Hello,

Thanks for creating such a cool piece of software. Out of all open 
source video conferencing systems we tested we prefer sylkserver and 
sylk-webrtc.
We're interested in using sylkserver with webrtc support for audio- and 
videoconferencing and want to run our setup without sip connectivity.
We also want to use authentication for our users and let them send 
invite links, but we don't want that everyone can open video conferences 
on our server.

Up to now we've managed to run sylkserver and sylk-webrtc on our server 
and create anonymous video conferences that worked well for some time.
But after about a minute one participant will disconnect and reconnect, 
while sylkserver logs 403 forbidden sip messages.

2020-03-25 13:20:43.557495 Packet 29 OUTGOING UDP XX:5060 -> XX:5060 
      │·
SIP/2.0 403 Forbidden 
                      │·
Via: SIP/2.0/UDP 
XX:5060;rport=5060;received=XX;branch=z9hG4bKPje736ed98-ad2e-│·
46ce-9f38-872120a72df2 
                      │·
Call-ID: ad5a3d35-1e58-4b98-913f-c4bd0a8686db 
                      │·
From: "dfsd" 
<sip:f6bf3e2e54874047 at guest.XX.at>;tag=62855d40-b9f1-4828-9a9b-8592bf830c│·
51 
                      │·
To: 
<sip:riverringereater6 at conference.XX.at>;tag=f0569ead-2caf-43fa-ad4e-43cfa261fbbe 
│·
CSeq: 5860 INVITE 
                      │·
Server: SylkServer-5.5.0 
                      │·
Content-Length:  0

what is going wrong here? is such a setup even possible?

Thanks for your help,
Valentin