[Users] one way audio problem with stun

Hi everybody, I have a "one way audio" problem. My enviroment is: xx.xx.63.75/27 = SER xx.xx.63.68/27 = Natbox (linux iptables masquerade) xx.xx.70.2/25 = STUN server xx.xx.63.78/27 = PAP1 linksys AOR 2000 10.1.1.233/24 = PAP2 linksys AOR 2001 (behind NATbox with stun enable) I have no audio from PAP1 to PAP2 when the call is made from PAP1 to PAP2, but when the call is made from PAP2 to PAP1 it works correctly. I see on the natbox that the RTP packet is droped with unreachable cause (icmp messages). This is the trace (ngrep) for the call from PAP1 to PAP2 on external interface of the natbox, where I can see STUN packets and the number udp port that the PAP willl be use (16444 to 16447). The problem is natbox use other port (1173). I don't know if this problem is on natbox or stun server or PAP. Can you helpme? Thanks!! U xx.xx.63.75:5060 -> xx.xx.63.68:5060 INVITE sip:2001@xx.xx.63.68:5060 SIP/2.0..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.41985863.0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..From: 2000 <sip:5 890000@xx.xx.63.75>;tag=d1ccd3db9e31eb1fo0..To: <sip:2001@xx.xx.63.75>..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Max-Forwards: 16..Contact: 2000 <sip:2000@xx.xx.63.78:5060>..Expires: 240..User-Agent: Linksys/PAP2-2.0.10(L Sc)..Content-Length: 420..Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER..Supported: x-sipura..Content-Type: app lication/sdp....v=0..o=- 29375 29375 IN IP4 xx.xx.63.78..s=-..c=IN IP4 xx.xx.63.78..t=0 0..m=audio 16472 RTP/AVP 18 0 2 4 8 9 6 97 98 100 101..a=rtpmap:18 G729a/8000..a=rtpmap:0 PCMU/8000..a=rtpmap:2 G726-32/8000..a=rtpmap:4 G723/8000..a=rtpmap:8 PCMA/8 000..a=rtpmap:96 G726-40/8000..a=rtpmap:97 G726-24/8000..a=rtpmap:98 G726-16/8000..a=rtpmap:100 NSE/8000..a=rtpmap:101 telephon e-event/8000..a=fmtp:101 0-15..a=ptime:30..a=sendrecv.. # U xx.xx.63.68:5060 -> xx.xx.63.75:5060 SIP/2.0 100 Trying..To: <sip:2001@xx.xx.63.75>..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd3db9e31eb1fo0..Call-ID : d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.41985863.0..Via: SIP/2.0/U DP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Server: Linksys/P AP2-2.0.10(LSc)..Content-Length: 0.... # U xx.xx.63.68:5060 -> xx.xx.70.2:3478 .....*f..*f..*f..*f. # U xx.xx.63.68:16444 -> xx.xx.70.2:3478 .....OB..OB..OB..OB. # U xx.xx.63.68:16445 -> xx.xx.70.2:3478 .................... # U xx.xx.63.68:16446 -> xx.xx.70.2:3478 .......&...&...&...& # U xx.xx.63.68:16447 -> xx.xx.70.2:3478 ....#...#...#...#... # U xx.xx.70.2:3478 -> xx.xx.63.68:16447 ...$#...#...#...#.........@?.+?D.........+F..........+F. # U xx.xx.63.68:5060 -> xx.xx.70.2:3478 .....*f..*f..*f..*f. # U xx.xx.63.68:16444 -> xx.xx.70.2:3478 .....OB..OB..OB..OB. # U xx.xx.70.2:3478 -> xx.xx.63.68:5060 ...$.*f..*f..*f..*f..........+?D.........+F..........+F. # U xx.xx.63.68:16445 -> xx.xx.70.2:3478 .................... # U xx.xx.63.68:16446 -> xx.xx.70.2:3478 .......&...&...&...& # U xx.xx.70.2:3478 -> xx.xx.63.68:16444 ...$.OB..OB..OB..OB.......@<.+?D.........+F..........+F. # U xx.xx.70.2:3478 -> xx.xx.63.68:16446 ...$...&...&...&...&......@>.+?D.........+F..........+F. # U xx.xx.63.68:5060 -> xx.xx.63.75:5060 SIP/2.0 180 Ringing..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd 3db9e31eb1fo0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.4198 5863.0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr= on>..Server: Linksys/PAP2-2.0.10(LSc)..Content-Length: 0.... # U xx.xx.70.2:3478 -> xx.xx.63.68:16444 ...$.OB..OB..OB..OB.......@<.+?D.........+F..........+F. # U xx.xx.63.68:5060 -> xx.xx.63.75:5060 SIP/2.0 200 OK..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd3db9e 31eb1fo0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.41985863. 0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>.. Contact: 2001 <sip:2001@xx.xx.63.68:5060>..Server: Linksys/PAP2-2.0.10(LSc)..Content-Length: 236..Allow: ACK, BYE, CANCE L, INFO, INVITE, NOTIFY, OPTIONS, REFER..Supported: x-sipura..Content-Type: application/sdp....v=0..o=- 659101 659101 IN IP4 20 0.43.63.68..s=-..c=IN IP4 xx.xx.63.68..t=0 0..m=audio 16444 RTP/AVP 18 100 101..a=rtpmap:18 G729a/8000..a=rtpmap:100 NSE/8000. .a=rtpmap:101 telephone-event/8000..a=fmtp:101 0-15..a=ptime:30..a=sendrecv.. # U xx.xx.63.75:5060 -> xx.xx.63.68:5060 ACK sip:2001@xx.xx.63.68:5060 SIP/2.0..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Via: SIP/2.0/UDP 200 .43.63.75;branch=0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-5a4c9c84..From: 2000 <sip:2000@xx.xx.63.75>;tag =d1ccd3db9e31eb1fo0..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 AC K..Max-Forwards: 16..Contact: 2000 <sip:2000@xx.xx.63.78:5060>..User-Agent: Linksys/PAP2-2.0.10(LSc)..Content-Length: 0.... # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8...-..L....@.....tF.34..V.|B..n..a.k(.R # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2....8...-..L....@.....tF.34..V.|B..n..a.k(.R # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!o..vy.F.!...|...&.T.BP..Z..n...:.3..d.. # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8......L... .s..._exR..Kc.....+.O<.RZ.O{ # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2....8......L... .s..._exR..Kc.....+.O<.RZ.O{ # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!p..wi.F.!.'D.F...K....@C..e.Z.[~P...Et, # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8.../..L......@H..._...,[.P...rU.A..P... # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2....8.../..L......@H..._...,[.P...rU.A..P... # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!q..xY.F.!....Mf.....Fu.Q.....~.}....v.. # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8...0..L..\.~..h..+..|S.C.M..~6W}....6sR # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2....8...0..L..\.~..h..+..|S.C.M..~6W}....6sR # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!r..yI.F.!x|..Eo..._.1...;..GRz....*.x.Z # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8...1..L..x.....n."..6.v....S.D.......S. # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2.!..8...1..L..x.....n."..6.v....S.D.......S. # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!s..z9.F.!0...ooPE..F. .5...E....v...... # U xx.xx.63.78:16472 -> xx.xx.63.68:16444 ..8...2..L..z....+.b..r?...r....|..$.x...^ # I xx.xx.63.68 -> xx.xx.63.78 3:3 ....E..F.........+?N.+?D@X@<.2....8...2..L..z....+.b..r?...r....|..$.x...^ # U xx.xx.63.68:1173 -> xx.xx.63.78:16472 ..!t..{).F.!.o...{..r..3....F.$.r.. 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