Hi! I am setting up Kamailio as SBC with upper registration. I can forward REGISTER messages to my softswitch, but 401 UNAUTHORIZED from it is not coming to my UAC. Config section for registration route:

route[REGISTER_MY] { rewritehost("3.3.3.3"); t_relay(); }

What I see with ngrep (1.1.1.1 - my external UAC ip, 2.2.2.2 - Kamailio ip, 3.3.3.3 - mera softswitch ip):

U 1.1.1.1:5060 -> 2.2.2.2:5060 REGISTER sip:2.2.2.2 SIP/2.0. Via: SIP/2.0/UDP 10.2.1.35:5060 ;rport;branch=z9hG4bKPj85d21f7f-5c1d-4b0b-8e82-940c5cc9e21d. Max-Forwards: 70. From: sip:101@2.2.2.2;tag=b00a1df7-94bd-4b2e-8f63-15fea1a9015b. To: sip:101@2.2.2.2. Call-ID: e789b66c-d96c-45ca-b3b8-06bf65a2c3d1. CSeq: 59629 REGISTER. User-Agent: SFLphone. Contact: sip:101@10.2.1.35:5060. Expires: 600. Allow: PRACK, SUBSCRIBE, NOTIFY, REFER, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, REGISTER, OPTIONS, MESSAGE. Content-Length: 0. .

U 2.2.2.2:5060 -> 1.1.1.1:5060 SIP/2.0 200 OK. Via: SIP/2.0/UDP 10.2.1.35:5060 ;rport=5060;branch=z9hG4bKPj85d21f7f-5c1d-4b0b-8e82-940c5cc9e21d;received=1.1.1.1. From: sip:101@2.2.2.2;tag=b00a1df7-94bd-4b2e-8f63-15fea1a9015b. To: sip:101@2.2.2.2;tag=2fb3028f366408eaa444e96dfd845447.8865. Call-ID: e789b66c-d96c-45ca-b3b8-06bf65a2c3d1. CSeq: 59629 REGISTER. Contact: sip:101@10.2.1.35:5060;expires=600. Server: kamailio (3.3.3 (x86_64/linux)). Content-Length: 0. .

U 2.2.2.2:5060 -> 3.3.3.3:5060 REGISTER sip:3.3.3.3 SIP/2.0. Via: SIP/2.0/UDP 2.2.2.2;branch=z9hG4bK929f.8339e446.0. Via: SIP/2.0/UDP 10.2.1.35:5060 ;received=1.1.1.1;rport=5060;branch=z9hG4bKPj85d21f7f-5c1d-4b0b-8e82-940c5cc9e21d. Max-Forwards: 69. From: sip:101@2.2.2.2;tag=b00a1df7-94bd-4b2e-8f63-15fea1a9015b. To: sip:101@2.2.2.2. Call-ID: e789b66c-d96c-45ca-b3b8-06bf65a2c3d1. CSeq: 59629 REGISTER. User-Agent: SFLphone. Contact: sip:101@10.2.1.35:5060. Expires: 600. Allow: PRACK, SUBSCRIBE, NOTIFY, REFER, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, REGISTER, OPTIONS, MESSAGE. Content-Length: 0. .

U 3.3.3.3:5060 -> 2.2.2.2:5060 SIP/2.0 401 Unauthorized. Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK929f.8339e446.0. Via: SIP/2.0/UDP 10.2.1.35:5060 ;received=1.1.1.1;rport=5060;branch=z9hG4bKPj85d21f7f-5c1d-4b0b-8e82-940c5cc9e21d. From: sip:101@2.2.2.2;tag=b00a1df7-94bd-4b2e-8f63-15fea1a9015b. To: sip:101@2.2.2.2;tag=d67d5778704611e2a3c600505691470a. Call-ID: e789b66c-d96c-45ca-b3b8-06bf65a2c3d1. CSeq: 59629 REGISTER. WWW-Authenticate: Digest realm="SIP-REGISTRAR", nonce="475a20c7". Server: MERA MVTS3G v.4.3.0-38t. Content-Length: 0. .

U 2.2.2.2:5060 -> 1.1.1.1:5060 SIP/2.0 401 Unauthorized. Via: SIP/2.0/UDP 10.2.1.35:5060 ;received=1.1.1.1;rport=5060;branch=z9hG4bKPj85d21f7f-5c1d-4b0b-8e82-940c5cc9e21d. From: sip:101@2.2.2.2;tag=b00a1df7-94bd-4b2e-8f63-15fea1a9015b. To: sip:101@2.2.2.2;tag=d67d5778704611e2a3c600505691470a. Call-ID: e789b66c-d96c-45ca-b3b8-06bf65a2c3d1. CSeq: 59629 REGISTER. WWW-Authenticate: Digest realm="SIP-REGISTRAR", nonce="475a20c7". Server: MERA MVTS3G v.4.3.0-38t. Content-Length: 0. .

Thanks in advance!

--- Alex Elokhov