1. The SIP-Based System Used in Connection with a Firewall Peter Koski, Jorma Ylinen, Pekka Loula Tampere University of Technology, Pori Pohjoisranta 11 A, P.O.Box 300, FIN-28101 Pori,Finland speaker ： Wenping Zhang date ： 2007.09.07

2. 2 Outline Introduction Types of NAT Technology Example Conclusion References

3. 3 Introduction Different methods, such as ALG, STUN, TURN and FCP have been proposed for using SIP together with firewalls and NAT. The most suitable solution has to be determined in every situation. In this paper a system which makes it possible to offer SIP service to customers behind NAT is presented.

4. 4 Types of NAT Full Cone Restricted Cone Port Restricted Cone Symmetric

5. 5 Full Cone

6. 6 Restricted Cone

7. 7 Port Restricted Cone

8. 8 Symmetric

9. 9 Technology 1/2 Simple Traversal of UDP through NATs (STUN)

10. 10 Technology 2/2 Traversal Using Relay NAT (TURN)

11. 11 Example 1/3 INVITE sip:6229002@193.167.88.44 SIP/2.0 Via: SIP/2.0/UDP 192.168.0.27:5060 ;branch=z9hG4bK58659f1f From: "6229001" ;tag=00115c40752 To: Call-ID: 00115c40-752@192.168.0.27 CSeq: 101 INVITE Contact: Content-Type: application/sdp Content-Length: 247 v=0 o=Cisco-SIPUA 25800 13441 IN IP4 192.168.0.27 s=SIP Call c=IN IP4 192.168.0.27 m=audio 26324 RTP/AVP 8 0 18 101 a=rtpmap:0 PCMU/8000 INVITE sip:6229002@193.167.88.43:5060 SIP/2.0 Record-Route: Via: SIP/2.0/UDP 193.167.88.44 Via: SIP/2.0/UDP 192.168.0.27:5060; rport=1162 ; received=193.167.88.45 From: "6229001" ;tag=00115c40752 To: Call-ID: 00115c40-752@192.168.0.27 CSeq: 101 INVITE Contact: Content-Type: application/sdp Content-Length: 286 v=0 o=Cisco-SIPUA 25800 13441 IN IP4 192.168.0.27 s=SIP Call c=IN IP4 193.167.88.44 m=audio 35080 RTP/AVP 8 0 18 101 a=rtpmap:0 PCMU/8000

12. 12 Example 2/3 Use STUN for SIP Registration

13. 13 Example 3/3 Use STUN for RTP

14. 14 Conclusion STUN and TURN require client support and this may be a problem in some cases. TURN can be used with a symmetric NAT, but few clients support TURN.

15. 15 References The SIP-Based System Used in Connection with a Firewall NAT Traversal for VoIP