Time out when negotiating connection

[ppv-milestone]

Hi,
I have an implementation using WebRTC part of SIPSorcery in place which 2 out of 3 times works fine, but approximately every third attempt the flow seems to stop midway and then eventually times out. The logs will show the below (I have replaced TURN server address with 1.2.3.4, TURN server uri with TURNURI and certificate with XYZ), but then next line will be a timeout:

2024-12-10 09:54:56.528+01:00 INFO - sipsorcery: No DTLS certificate is provided in the configuration
2024-12-10 09:54:56.553+01:00 INFO - sipsorcery: RTCPeerConnection created with DTLS certificate with fingerprint sha-256 AC:F4:AC:A2:D6:EA:71:27:70:EC:BB:5E:82:DF:DE:92:B0:C9:47:E8:93:B4:63:D8:8A:17:E5:D3:6E:95:29:F3 and signature algorithm SHA256withECDSA.
2024-12-10 09:54:56.570+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2024-12-10 09:54:56.587+01:00 INFO - sipsorcery: CreateRtpSocket attempting to create and bind RTP socket(s) on [::]:0.
2024-12-10 09:54:56.611+01:00 INFO - sipsorcery: CreateBoundSocket attempting to create and bind socket(s) on [::]:0 using protocol Udp.
2024-12-10 09:54:56.633+01:00 INFO - sipsorcery: CreateBoundSocket successfully bound on [::]:57918, dual mode True.
2024-12-10 09:54:56.649+01:00 INFO - sipsorcery: Successfully bound RTP socket [::]:57918 (dual mode True).
2024-12-10 09:54:56.671+01:00 INFO - sipsorcery: CreateRtpSocket attempting to create and bind RTP socket(s) on [::]:0.
2024-12-10 09:54:56.689+01:00 INFO - sipsorcery: CreateBoundSocket attempting to create and bind socket(s) on [::]:0 using protocol Tcp.
2024-12-10 09:54:56.713+01:00 INFO - sipsorcery: CreateBoundSocket even port required, closing socket on [::]:34347 and retrying on 34348.
2024-12-10 09:54:56.737+01:00 INFO - sipsorcery: Successfully bound RTP socket [::]:34348 (dual mode True).
2024-12-10 09:54:56.759+01:00 INFO - sipsorcery: RTPChannel for [::]:57918 started.
2024-12-10 09:54:56.778+01:00 INFO - SIPSorcery.Net.SctpDataReceiver: SCTP windows size for data receiver set at 218.
2024-12-10 09:54:56.793+01:00 INFO - sipsorcery: SCTP creating DTLS based association, is DTLS client False, ID 5000:5000:57918.
2024-12-10 09:54:56.814+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI.
2024-12-10 09:54:56.837+01:00 INFO - sipsorcery: RTPIceChannel TCP for [::]:57918 started.
2024-12-10 09:54:56.874+01:00 INFO - sipsorcery: RTP ICE Channel discovered 0 local candidates.
2024-12-10 09:54:56.896+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI.
2024-12-10 09:54:56.915+01:00 INFO - sipsorcery: Attempting to resolve STUN server URI turn:TURNURI.
2024-12-10 09:54:56.932+01:00 INFO - sipsorcery: ICE server turn:TURNURI successfully resolved to 1.2.3.4:443.
2024-12-10 09:54:56.973+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.116+01:00 INFO - sipsorcery: SendOverTCP status: True endpoint: [::ffff:1.2.3.4]:443
2024-12-10 09:54:57.162+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.225+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.289+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.351+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.413+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.477+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI with address 1.2.3.4:443.
2024-12-10 09:54:57.490+01:00 INFO - sipsorcery: TURN allocate success response received for ICE server check to turn:TURNURI.
2024-12-10 09:54:57.501+01:00 INFO - sipsorcery: Adding relay ICE candidate for ICE server turn:TURNURI and 1.2.3.4:27356.
2024-12-10 09:54:57.539+01:00 INFO - sipsorcery: ICE RTP channel stopping ICE server checks in gathering state complete and connection state new.
2024-12-10 09:54:58.552+01:00 INFO - sipsorcery: RTP ICE Channel remote credentials set.
2024-12-10 09:54:58.576+01:00 INFO - sipsorcery: RTP ICE Channel received remote candidate: 2558687369 1 udp 16777215 1.2.3.4 31186 typ relay raddr 10.24.31.13 rport 34750 generation 0
2024-12-10 09:54:58.596+01:00 INFO - sipsorcery: Remote ICE candidate not added as no available ICE session for component rtcp.
2024-12-10 09:54:58.609+01:00 INFO - sipsorcery: Adding new candidate pair to checklist for: udp:1.2.3.4:27356 (relay)->udp:1.2.3.4:31186 (relay)
2024-12-10 09:54:58.611+01:00 INFO - sipsorcery: LogRemoteSDPSsrcAttributes: Audio:[ ] 
 Video: [  ]
2024-12-10 09:54:58.622+01:00 INFO - sipsorcery: ICE RTP channel sending TURN permissions request 1 to server turn:TURNURI for peer 1.2.3.4:31186 (TxID: LWEQUAFGHWIN).
2024-12-10 09:54:58.773+01:00 INFO - sipsorcery: A TURN Create Permission success response was received from [::]:0 (TxID: LWEQUAFGHWIN).
2024-12-10 09:54:58.800+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:27356 (relay)->udp:1.2.3.4:31186 (relay) from [::]:57918 to relay at 1.2.3.4:443 (use candidate False).
2024-12-10 09:54:58.945+01:00 INFO - sipsorcery: ICE RTP channel binding response state Succeeded as Controller for udp:1.2.3.4:31186 (relay)
2024-12-10 09:54:58.955+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:27356 (relay)->udp:1.2.3.4:31186 (relay) from [::]:57918 to relay at 1.2.3.4:443 (use candidate True).

The times where it work I get the exact same, but then it will continue with this:

2024-12-10 09:55:43.264+01:00 INFO - sipsorcery: ICE RTP channel remote peer nominated entry from binding response udp:1.2.3.4:33271 (relay)
2024-12-10 09:55:43.275+01:00 INFO - sipsorcery: ICE RTP channel connected after 2459ms udp:1.2.3.4:33270 (relay)->udp:1.2.3.4:33271 (relay).
2024-12-10 09:55:43.315+01:00 INFO - sipsorcery: ICE connected to remote end point 1.2.3.4:33271.
2024-12-10 09:55:43.337+01:00 INFO - sipsorcery: Starting DLS handshake with role passive.
2024-12-10 09:55:43.356+01:00 INFO - sipsorcery: RTCPeerConnection DoDtlsHandshake started.
2024-12-10 09:55:43.374+01:00 INFO - sipsorcery: DTLS commencing handshake as server.
2024-12-10 09:55:43.398+01:00 INFO - sipsorcery: Server offered cipher suites:
 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
 DRAFT_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
2024-12-10 09:55:43.408+01:00 INFO - sipsorcery: Client offered cipher suites:
 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
2024-12-10 09:55:43.428+01:00 INFO - sipsorcery: Selected cipher suite: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256. Using SHA256withECDSA certificate with fingerprint sha-256 EA:B1:56:02:CD:F0:54:73:7F:73:5A:3E:27:31:42:0D:2D:35:CA:64:E5:00:30:3B:60:3F:9A:2D:4C:4B:67:23.
2024-12-10 09:55:43.722+01:00 INFO - sipsorcery: RTCPeerConnection DTLS handshake result True, is handshake complete True.
2024-12-10 09:55:43.747+01:00 INFO - sipsorcery: Remote peer DTLS certificate, signature algorithm SHA256withECDSA.
2024-12-10 09:55:43.766+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2024-12-10 09:55:43.780+01:00 INFO - sipsorcery: RTCPeerConnection remote certificate fingerprint matched expected value of FE:50:1F:8B:5F:A8:AD:7C:57:A1:6A:D9:FF:23:12:ED:BF:5B:A3:49:44:8C:90:44:AB:0D:1E:DE:18:E0:75:C4 for sha-256.

We have another web based client towards the same servers and do not see the same issue there. Does anyone have an idea what could be the reason why "ICE RTP channel sending connectivity check for" often times out?

[sipsorcery]

I can replicate the same behaviour and log messages if I re-use an RTCPeerConnection instance. Each instance is only intended to be used once. For each new WebRTC peer connection you should be creating a brand new instance.

If it helps I use the webrtccmdline tool to test scenarios like this.

Signalling server peer:

sipsorcery\examples\webrtccmdline>dotnet run --ws --stun turn:azamicrok8s?transport=tcp --relayonly --accepticetypes=relay

Signalling client peer:

sipsorcery\examples\webrtccmdline>dotnet run --wsclient ws://127.0.0.1:8081 --stun turn:azamicrok8s?transport=tcp --relayonly --accepticetypes=relay

[sipsorcery]

I'm still trying to reproduce this. It turns out the issue I had previously was due to my ICE candidates not being exchanged properly.

Are you able to test your TURN server connection with UDP instead of TCP? It would be useful to know if the issue happens with UDP as well.

[ppv-milestone]

Sorry for the delayed response - I have been offline for a few days due to the holidays.
The issue happens with UDP as well and I get quite similar logs:

2025-01-02 08:52:40.439+01:00 INFO - sipsorcery: No DTLS certificate is provided in the configuration
2025-01-02 08:52:40.441+01:00 INFO - sipsorcery: RTCPeerConnection created with DTLS certificate with fingerprint sha-256 AE:92:80:EE:41:0E:44:47:8B:FA:32:F1:2D:92:DD:CF:00:86:72:E4:6E:54:91:52:27:7B:99:48:C9:AE:18:23 and signature algorithm SHA256withECDSA.
2025-01-02 08:52:40.442+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2025-01-02 08:52:40.442+01:00 INFO - sipsorcery: CreateRtpSocket attempting to create and bind RTP socket(s) on [::]:0.
2025-01-02 08:52:40.443+01:00 INFO - sipsorcery: CreateBoundSocket attempting to create and bind socket(s) on [::]:0 using protocol Udp.
2025-01-02 08:52:40.444+01:00 INFO - sipsorcery: CreateBoundSocket successfully bound on [::]:61704, dual mode True.
2025-01-02 08:52:40.445+01:00 INFO - sipsorcery: Successfully bound RTP socket [::]:61704 (dual mode True).
2025-01-02 08:52:40.445+01:00 INFO - sipsorcery: RTPChannel for [::]:61704 started.
2025-01-02 08:52:40.446+01:00 INFO - SIPSorcery.Net.SctpDataReceiver: SCTP windows size for data receiver set at 218.
2025-01-02 08:52:40.447+01:00 INFO - sipsorcery: SCTP creating DTLS based association, is DTLS client False, ID 5000:5000:61704.
2025-01-02 08:52:40.448+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-02 08:52:40.449+01:00 INFO - sipsorcery: RTP ICE Channel discovered 0 local candidates.
2025-01-02 08:52:40.450+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-02 08:52:40.451+01:00 INFO - sipsorcery: Attempting to resolve STUN server URI turn:TURNURI:443.
2025-01-02 08:52:40.452+01:00 INFO - sipsorcery: ICE server turn:TURNURI:443 successfully resolved to 1.2.3.4:443.
2025-01-02 08:52:40.502+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-02 08:52:40.565+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-02 08:52:40.627+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-02 08:52:40.691+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-02 08:52:40.749+01:00 INFO - sipsorcery: TURN allocate success response received for ICE server check to turn:TURNURI:443.
2025-01-02 08:52:40.750+01:00 INFO - sipsorcery: Adding relay ICE candidate for ICE server turn:TURNURI:443 and 1.2.3.4:31864.
2025-01-02 08:52:40.752+01:00 INFO - sipsorcery: ICE RTP channel stopping ICE server checks in gathering state complete and connection state new.
2025-01-02 08:52:41.514+01:00 INFO - sipsorcery: RTP ICE Channel remote credentials set.
2025-01-02 08:52:41.515+01:00 INFO - sipsorcery: RTP ICE Channel received remote candidate: 2558687369 1 udp 16777215 1.2.3.4 28920 typ relay raddr 0.0.0.0 rport 57045 generation 0
2025-01-02 08:52:41.515+01:00 INFO - sipsorcery: Remote ICE candidate not added as no available ICE session for component rtcp.
2025-01-02 08:52:41.516+01:00 INFO - sipsorcery: LogRemoteSDPSsrcAttributes: Audio:[ ] 
 Video: [  ]
2025-01-02 08:52:41.560+01:00 INFO - sipsorcery: Adding new candidate pair to checklist for: udp:1.2.3.4:31864 (relay)->udp:1.2.3.4:28920 (relay)
2025-01-02 08:52:41.561+01:00 INFO - sipsorcery: ICE RTP channel sending TURN permissions request 1 to server turn:TURNURI:443 for peer 1.2.3.4:28920 (TxID: QZYFCALJTICH).
2025-01-02 08:52:41.684+01:00 INFO - sipsorcery: A TURN Create Permission success response was received from 1.2.3.4:443 (TxID: QZYFCALJTICH).
2025-01-02 08:52:41.686+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:31864 (relay)->udp:1.2.3.4:28920 (relay) from [::]:61704 to relay at 1.2.3.4:443 (use candidate False).
2025-01-02 08:52:41.809+01:00 INFO - sipsorcery: ICE RTP channel binding response state Succeeded as Controller for udp:1.2.3.4:28920 (relay)
2025-01-02 08:52:41.810+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:31864 (relay)->udp:1.2.3.4:28920 (relay) from [::]:61704 to relay at 1.2.3.4:443 (use candidate True).

[ppv-milestone]

In an attempt to try to figure out what goes different between when connection is established correctly and when not, I started adding some logging various places (as debugging will cause the issue to stop from happening).
First thing I have observed which might not be of any relevance, but still seems to be a very consistent difference between successful and non-successful attempts is that when the attempt is successful, slightly before (approximately 40ms) the "binding response state Succeeded as Controller" I get one log indication that a STUN message with MessageType BindingRequest has been received (line 1970 in RtpIceChannel). Also, immeditately after (within 1ms) the "sending connectivity check" message in the logs I get another Binding Request, but not any more of these before the "remote peer nominated entry from binding response" log indicating that a successful binding response has been received approximately 120 ms later.
When the attempt is non-successful I see no BindingRequest before, but the same one within the 1ms after "sending connectivity check", but I then always get exactly two more BindingRequests within the next approximately 120 ms until the log then goes silent until I close the connection attempt due to timeout.
To summarize, if we name BindingRequest 'BR', and the "binding response state Succeeded as Controller" 'SUC', and the "sending connectivity check" 'SCC', I get the following sequences consistently:
Successful: BR, SUC, SCC, BR
Non-successful: SUC, SCC, BR, BR, BR
I am sorry if this is not of any relevance and honestly maybe not very well described, but since the problem seems to be about timing, I think it is worth sharing since it seems to be so consistent.

[sipsorcery]

Can you add the two debug messages as below to your app. The idea is to see if a STUN response is being received to the use candidate check.

pc.GetRtpChannel().OnStunMessageSent += (msg, ep, isRelay) => logger.LogDebug($"STUN {msg.Header.MessageType} message sent to {ep} (is relay {isRelay}).");
pc.GetRtpChannel().OnStunMessageReceived += (msg, ep, isRelay) => logger.LogDebug($"STUN {msg.Header.MessageType} message received from {ep} (is relay {isRelay}).");

[ppv-milestone]

I have now run again with these added (log starts with "INFO - WebRTC:".
Successful attempt:

2025-01-03 07:34:55.033+01:00 INFO - sipsorcery: No DTLS certificate is provided in the configuration
2025-01-03 07:34:55.035+01:00 INFO - sipsorcery: RTCPeerConnection created with DTLS certificate with fingerprint sha-256 3B:D3:D0:C0:7B:AA:B0:B1:21:39:58:6F:6C:E6:71:4F:04:CB:FE:58:2F:47:81:2F:79:C8:BA:73:C0:AC:B6:9A and signature algorithm SHA256withECDSA.
2025-01-03 07:34:55.035+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2025-01-03 07:34:55.036+01:00 INFO - sipsorcery: CreateRtpSocket attempting to create and bind RTP socket(s) on [::]:0.
2025-01-03 07:34:55.036+01:00 INFO - sipsorcery: CreateBoundSocket attempting to create and bind socket(s) on [::]:0 using protocol Udp.
2025-01-03 07:34:55.037+01:00 INFO - sipsorcery: CreateBoundSocket successfully bound on [::]:56188, dual mode True.
2025-01-03 07:34:55.038+01:00 INFO - sipsorcery: Successfully bound RTP socket [::]:56188 (dual mode True).
2025-01-03 07:34:55.039+01:00 INFO - sipsorcery: RTPChannel for [::]:56188 started.
2025-01-03 07:34:55.040+01:00 INFO - SIPSorcery.Net.SctpDataReceiver: SCTP windows size for data receiver set at 218.
2025-01-03 07:34:55.040+01:00 INFO - sipsorcery: SCTP creating DTLS based association, is DTLS client False, ID 5000:5000:56188.
2025-01-03 07:34:55.041+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-03 07:34:55.042+01:00 INFO - sipsorcery: RTP ICE Channel discovered 0 local candidates.
2025-01-03 07:34:55.043+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-03 07:34:55.043+01:00 INFO - sipsorcery: Attempting to resolve STUN server URI turn:TURNURI:443.
2025-01-03 07:34:55.045+01:00 INFO - sipsorcery: ICE server turn:TURNURI:443 successfully resolved to 1.2.3.4:443.
2025-01-03 07:34:55.117+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:34:55.117+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.177+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:34:55.178+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.238+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:34:55.239+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.262+01:00 INFO - WebRTC: STUN AllocateErrorResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.301+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:34:55.301+01:00 INFO - WebRTC: STUN AllocateErrorResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.302+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.361+01:00 INFO - WebRTC: STUN AllocateErrorResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.364+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:34:55.365+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.424+01:00 INFO - WebRTC: STUN AllocateSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:55.424+01:00 INFO - sipsorcery: TURN allocate success response received for ICE server check to turn:TURNURI:443.
2025-01-03 07:34:55.425+01:00 INFO - sipsorcery: Adding relay ICE candidate for ICE server turn:TURNURI:443 and 1.2.3.4:28538.
2025-01-03 07:34:55.488+01:00 INFO - sipsorcery: ICE RTP channel stopping ICE server checks in gathering state complete and connection state new.
2025-01-03 07:34:56.502+01:00 INFO - sipsorcery: RTP ICE Channel remote credentials set.
2025-01-03 07:34:56.503+01:00 INFO - sipsorcery: RTP ICE Channel received remote candidate: 2558687369 1 udp 16777215 1.2.3.4 30918 typ relay raddr 0.0.0.0 rport 38702 generation 0
2025-01-03 07:34:56.504+01:00 INFO - sipsorcery: Remote ICE candidate not added as no available ICE session for component rtcp.
2025-01-03 07:34:56.504+01:00 INFO - sipsorcery: LogRemoteSDPSsrcAttributes: Audio:[ ] 
 Video: [  ]
2025-01-03 07:34:56.505+01:00 INFO - WebRTC: STUN AllocateSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:56.570+01:00 INFO - sipsorcery: Adding new candidate pair to checklist for: udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay)
2025-01-03 07:34:56.571+01:00 INFO - sipsorcery: ICE RTP channel sending TURN permissions request 1 to server turn:TURNURI:443 for peer 1.2.3.4:30918 (TxID: IDQZOVANAKMQ).
2025-01-03 07:34:56.572+01:00 INFO - WebRTC: STUN CreatePermission message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:34:56.694+01:00 INFO - WebRTC: STUN CreatePermissionSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:34:56.694+01:00 INFO - sipsorcery: A TURN Create Permission success response was received from 1.2.3.4:443 (TxID: IDQZOVANAKMQ).
2025-01-03 07:34:56.696+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay) from [::]:56188 to relay at 1.2.3.4:443 (use candidate False).
2025-01-03 07:34:56.697+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.722+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.723+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.723+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.820+01:00 INFO - WebRTC: STUN BindingSuccessResponse message received from 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.820+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay) from [::]:56188 to relay at 1.2.3.4:443 (use candidate True).
2025-01-03 07:34:56.821+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.821+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.821+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.821+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.943+01:00 INFO - WebRTC: STUN BindingSuccessResponse message received from 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:56.944+01:00 INFO - sipsorcery: ICE RTP channel connected after 1902ms udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay).
2025-01-03 07:34:56.945+01:00 INFO - sipsorcery: ICE connected to remote end point 1.2.3.4:30918.
2025-01-03 07:34:56.945+01:00 INFO - sipsorcery: Starting DLS handshake with role passive.
2025-01-03 07:34:56.945+01:00 INFO - sipsorcery: RTCPeerConnection DoDtlsHandshake started.
2025-01-03 07:34:56.946+01:00 INFO - sipsorcery: DTLS commencing handshake as server.
2025-01-03 07:34:56.947+01:00 INFO - sipsorcery: Server offered cipher suites:
 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
 DRAFT_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
2025-01-03 07:34:56.947+01:00 INFO - sipsorcery: Client offered cipher suites:
 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
2025-01-03 07:34:56.948+01:00 INFO - sipsorcery: Selected cipher suite: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256. Using SHA256withECDSA certificate with fingerprint sha-256 3B:D3:D0:C0:7B:AA:B0:B1:21:39:58:6F:6C:E6:71:4F:04:CB:FE:58:2F:47:81:2F:79:C8:BA:73:C0:AC:B6:9A.
2025-01-03 07:34:56.948+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.949+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.950+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.951+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:56.952+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.077+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.078+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.079+01:00 INFO - sipsorcery: RTCPeerConnection DTLS handshake result True, is handshake complete True.
2025-01-03 07:34:57.080+01:00 INFO - sipsorcery: Remote peer DTLS certificate, signature algorithm SHA256withECDSA.
2025-01-03 07:34:57.081+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2025-01-03 07:34:57.082+01:00 INFO - sipsorcery: RTCPeerConnection remote certificate fingerprint matched expected value of 6E:84:DF:BC:B2:C5:50:67:12:EF:51:6C:35:A7:42:05:DB:43:8D:1E:84:74:7F:30:96:51:34:1E:98:E8:77:9F for sha-256.
2025-01-03 07:34:57.100+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.175+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.233+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.300+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.360+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.421+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.492+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.552+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.620+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.679+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.740+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.807+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.872+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:57.940+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.000+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.061+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.127+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.193+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.261+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.321+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.381+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.453+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.514+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.580+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.640+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.699+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.773+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.833+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.902+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:58.956+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:59.124+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:30918 (is relay True).
2025-01-03 07:34:59.125+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:34:59.125+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:30918 (is relay True).

Failed attempt:

2025-01-03 07:35:09.383+01:00 INFO - sipsorcery: No DTLS certificate is provided in the configuration
2025-01-03 07:35:09.385+01:00 INFO - sipsorcery: RTCPeerConnection created with DTLS certificate with fingerprint sha-256 D8:75:25:7A:97:53:74:50:6B:B7:17:51:9F:A3:1B:D7:69:CC:1E:00:1C:15:8E:E8:C3:71:E0:D4:6F:66:63:48 and signature algorithm SHA256withECDSA.
2025-01-03 07:35:09.386+01:00 INFO - sipsorcery: -----BEGIN CERTIFICATE-----
XYZ
-----END CERTIFICATE-----
2025-01-03 07:35:09.387+01:00 INFO - sipsorcery: CreateRtpSocket attempting to create and bind RTP socket(s) on [::]:0.
2025-01-03 07:35:09.387+01:00 INFO - sipsorcery: CreateBoundSocket attempting to create and bind socket(s) on [::]:0 using protocol Udp.
2025-01-03 07:35:09.389+01:00 INFO - sipsorcery: CreateBoundSocket even port required, closing socket on [::]:61581 and retrying on 61582.
2025-01-03 07:35:09.390+01:00 INFO - sipsorcery: Successfully bound RTP socket [::]:61582 (dual mode True).
2025-01-03 07:35:09.390+01:00 INFO - sipsorcery: RTPChannel for [::]:61582 started.
2025-01-03 07:35:09.391+01:00 INFO - SIPSorcery.Net.SctpDataReceiver: SCTP windows size for data receiver set at 218.
2025-01-03 07:35:09.392+01:00 INFO - sipsorcery: SCTP creating DTLS based association, is DTLS client False, ID 5000:5000:61582.
2025-01-03 07:35:09.393+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-03 07:35:09.395+01:00 INFO - sipsorcery: RTP ICE Channel discovered 0 local candidates.
2025-01-03 07:35:09.396+01:00 INFO - sipsorcery: Adding ICE server for turn:TURNURI:443.
2025-01-03 07:35:09.397+01:00 INFO - sipsorcery: Attempting to resolve STUN server URI turn:TURNURI:443.
2025-01-03 07:35:09.399+01:00 INFO - sipsorcery: ICE server turn:TURNURI:443 successfully resolved to 1.2.3.4:443.
2025-01-03 07:35:09.448+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:35:09.449+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.512+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:35:09.513+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.571+01:00 INFO - WebRTC: STUN AllocateErrorResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.574+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:35:09.575+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.634+01:00 INFO - WebRTC: STUN AllocateErrorResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.638+01:00 INFO - sipsorcery: Sending TURN allocate request to ICE server turn:TURNURI:443 with address 1.2.3.4:443.
2025-01-03 07:35:09.639+01:00 INFO - WebRTC: STUN Allocate message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.697+01:00 INFO - WebRTC: STUN AllocateSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:35:09.697+01:00 INFO - sipsorcery: TURN allocate success response received for ICE server check to turn:TURNURI:443.
2025-01-03 07:35:09.697+01:00 INFO - sipsorcery: Adding relay ICE candidate for ICE server turn:TURNURI:443 and 1.2.3.4:33080.
2025-01-03 07:35:09.700+01:00 INFO - sipsorcery: ICE RTP channel stopping ICE server checks in gathering state complete and connection state new.
2025-01-03 07:35:10.657+01:00 INFO - sipsorcery: RTP ICE Channel remote credentials set.
2025-01-03 07:35:10.658+01:00 INFO - sipsorcery: RTP ICE Channel received remote candidate: 4006836086 1 udp 16777215 1.2.3.4 31307 typ relay raddr 0.0.0.0 rport 55533 generation 0
2025-01-03 07:35:10.659+01:00 INFO - sipsorcery: Remote ICE candidate not added as no available ICE session for component rtcp.
2025-01-03 07:35:10.659+01:00 INFO - sipsorcery: LogRemoteSDPSsrcAttributes: Audio:[ ] 
 Video: [  ]
2025-01-03 07:35:10.661+01:00 INFO - WebRTC: STUN AllocateSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:35:10.709+01:00 INFO - sipsorcery: Adding new candidate pair to checklist for: udp:1.2.3.4:33080 (relay)->udp:1.2.3.4:31307 (relay)
2025-01-03 07:35:10.710+01:00 INFO - sipsorcery: ICE RTP channel sending TURN permissions request 1 to server turn:TURNURI:443 for peer 1.2.3.4:31307 (TxID: QYGRELIJPFAW).
2025-01-03 07:35:10.710+01:00 INFO - WebRTC: STUN CreatePermission message sent to 1.2.3.4:443 (is relay False).
2025-01-03 07:35:10.903+01:00 INFO - WebRTC: STUN CreatePermissionSuccessResponse message received from 1.2.3.4:443 (is relay False).
2025-01-03 07:35:10.904+01:00 INFO - sipsorcery: A TURN Create Permission success response was received from 1.2.3.4:443 (TxID: QYGRELIJPFAW).
2025-01-03 07:35:10.958+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:33080 (relay)->udp:1.2.3.4:31307 (relay) from [::]:61582 to relay at 1.2.3.4:443 (use candidate False).
2025-01-03 07:35:10.958+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:35:11.081+01:00 INFO - WebRTC: STUN BindingSuccessResponse message received from 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.081+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:33080 (relay)->udp:1.2.3.4:31307 (relay) from [::]:61582 to relay at 1.2.3.4:443 (use candidate True).
2025-01-03 07:35:11.082+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:35:11.082+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.082+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:35:11.082+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.095+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.096+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:35:11.096+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.203+01:00 INFO - WebRTC: STUN BindingRequest message received from 1.2.3.4:31307 (is relay True).
2025-01-03 07:35:11.203+01:00 INFO - WebRTC: STUN SendIndication message sent to 1.2.3.4:443 (is relay True).
2025-01-03 07:35:11.204+01:00 INFO - WebRTC: STUN BindingSuccessResponse message sent to 1.2.3.4:31307 (is relay True).

I am truely grateful for your continued support on this. Thanks! Please let me know if there is anything else I should try out.

[sipsorcery]

Thanks for the additional logs. The key difference between the success and failure cases is this log message:

WebRTC: STUN BindingSuccessResponse message received from 1.2.3.4:30918 (is relay True).

In the success case that STUN response is received AFTER the ICE candidate is nominated, which is indicated in the log message below with the use candidate True.

INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay) from [::]:56188 to relay at 1.2.3.4:443 (use candidate True).

The question is now why isn't the STUN binding success response received from the TURN server in some cases. If you're able to use WireShark it would be very helpful to get a packet capture of the STUN messages to/from the TURN server during the success and failure cases. That should fairly definitively point to the sipsorcery library being the culprit or not. If you do capture a WireShark trace you can send it directly to me at [email protected] to avoid publishing you IP addresses.

[ppv-milestone]

I have now mailed you the two pcap files. Please let me know if you do not receive them.

[sipsorcery]

Got them, thanks.

[sipsorcery]

The problem is that after the sipsorcery end sends the nominated ICE candidate STUN binding request, as indicated by:, the log message below the response is not received from the TURN server.

025-01-03 07:34:56.820+01:00 INFO - sipsorcery: ICE RTP channel sending connectivity check for udp:1.2.3.4:28538 (relay)->udp:1.2.3.4:30918 (relay) from [::]:56188 to relay at 1.2.3.4:443 (use candidate True).

In the success case this log message lets the sipsorcery end know the ICE channel is connected and to proceed to the DTLS handshake (note the response needs to be after the request sent in the preceeding log message):

2025-01-03 07:34:56.943+01:00 INFO - WebRTC: STUN BindingSuccessResponse message received from 1.2.3.4:30918 (is relay True).

In the failure case that log message never appears and from an initial look at the WireShark captures the response is not showing up in it either.

The next question is why the remote peer is not sending the BindingSuccessResponse? Is the remote peer a browser? If it's chrome could you see if anything shows up in chrome://webrtc-internals/ when you get a failure particularly around the ICE events.