Hello Everyone,

I’m running into a problem with Kamailio and Asterisk inside Kubernetes. Both are exposed to the outside.

My Network: External IP: 192.168.1.99:32210 TCP

Kamailio Service IP: 10.101.179.164 Kamailio Pod IP: 10.244.10.35

Asterisk Service IP: 10.99.122.141 Asterisk Pod IP: 10.244.10.38

The issue is:

When connecting directly to Asterisk, SIP calls work with not problems if I remove the local_net setting, so that Asterisk advertises its external IP. When connecting through Kamailio as a proxy, calls only “works” if I enable local_net, but still client can't send ACK to 200 OK. I believe the problem is that Asterisk sets the Contact header to its pod IP instead of the Service IP and Kamailio is not able to send ACK which leads to call timeout. Any Ideas?

My Transport:

[transport-tcp-nat] type=transport protocol=tcp bind=0.0.0.0 local_net=10.244.10.0/16 local_net=10.96.0.0/12 external_media_address=192.168.1.99 external_signaling_address=192.168.1.99 external_signaling_port=32210

SIP Logs:

<--- Transmitting SIP response (1293 bytes) to UDP:10.244.10.35:5001 ---> SIP/2.0 200 OK Via: SIP/2.0/UDP 192.168.1.190:5001;rport=5001;received=10.244.10.35;branch=z9hG4bK683e.ce5a170c8d281e2227ec5a8870044ad9.0;i=4 Via: SIP/2.0/TCP 10.244.10.1:54435;rport=54435;received=10.244.10.1;branch=z9hG4bKPjb54c457d4a7d48959ca03391a56e1136;alias Call-ID: d0e65953da0f406498b95e77aae9f850 From: sip:6001@192.168.1.99;tag=d9761b4e52944f068f85ff71d139f660 To: sip:100@192.168.1.99;tag=76784095-78d9-4467-88e6-d9fba8bfbcd6 CSeq: 21022 INVITE Server: Asterisk PBX 18.24.3 Contact: sip:10.244.10.38:5060 Allow: OPTIONS, REGISTER, SUBSCRIBE, NOTIFY, PUBLISH, INVITE, ACK, BYE, CANCEL, UPDATE, PRACK, INFO, MESSAGE, REFER Supported: 100rel, timer, replaces, norefersub Session-Expires: 1800;refresher=uac Require: timer Content-Type: application/sdp Content-Length: 487

v=0 o=- 3966074837 3966074839 IN IP4 10.244.10.38 s=Asterisk c=IN IP4 10.244.10.38 t=0 0 m=audio 10056 RTP/AVP 9 0 101 a=ice-ufrag:4e2d77c12b938bbc4c7f3c773f3a262a a=ice-pwd:5df2f60432675fb26b988faa6a42c1c1 a=candidate:Hc0a80163 1 UDP 2130706431 192.168.1.99 10056 typ host a=candidate:Hc0a80163 2 UDP 2130706430 192.168.1.99 10057 typ host a=rtpmap:9 G722/8000 a=rtpmap:0 PCMU/8000 a=ptime:20 a=maxptime:140 a=sendrecv a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16

Kamailio Log:

17(65) WARNING: <script>: [onsend_route] Packet going to sip:10.99.122.141:5060 17(65) WARNING: <script>: [RTPENGINE] ACK 17(65) WARNING: <script>: [REQUEST]: d0e65953da0f406498b95e77aae9f850: got ACK

ACK sip:100@192.168.1.99:31953;transport=tcp SIP/2.0 Via: SIP/2.0/TCP 10.244.10.1:54435;rport;branch=z9hG4bKPj130d3b53570f45afa764dd874a115771;alias Max-Forwards: 70 From: sip:6001@192.168.1.99;tag=d9761b4e52944f068f85ff71d139f660 To: sip:100@192.168.1.99;tag=z9hG4bK983e.12c423f5a5497fcaafae93af5228672e.0 Call-ID: d0e65953da0f406498b95e77aae9f850 CSeq: 21021 ACK Content-Length: 0

WireShark Log:

Session Initiation Protocol (ACK) Request-Line: ACK sip:10.244.10.38:5060 SIP/2.0 Method: ACK Request-URI: sip:10.244.10.38:5060 Request-URI Host Part: 10.244.10.38 Request-URI Host Port: 5060 [Resent Packet: False] [Request Frame: 2849862] [Response Time (ms): 3968] Message Header Via: SIP/2.0/UDP 192.168.1.163:49666;rport;branch=z9hG4bKPje5005f15847d460d81553d1f5a5e0393 Transport: UDP Sent-by Address: 192.168.1.163 Sent-by port: 49666 RPort: rport Branch: z9hG4bKPje5005f15847d460d81553d1f5a5e0393 Max-Forwards: 70 From: sip:6001@192.168.1.99;tag=d8b13b005dda4b008eaf52f5d7c1f902 SIP from address: sip:6001@192.168.1.99 SIP from address User Part: 6001 SIP from address Host Part: 192.168.1.99 SIP from tag: d8b13b005dda4b008eaf52f5d7c1f902 To: sip:100@192.168.1.99;tag=768c6b9f-afd5-4546-b650-8616bbec7fd7 SIP to address: sip:100@192.168.1.99 SIP to address User Part: 100 SIP to address Host Part: 192.168.1.99 SIP to tag: 768c6b9f-afd5-4546-b650-8616bbec7fd7 Call-ID: 210137ed6d6145bc8f864a6b1d9f0f31 [Generated Call-ID: 210137ed6d6145bc8f864a6b1d9f0f31] CSeq: 8750 ACK Sequence Number: 8750 Method: ACK Content-Length: 0

Thank you.