H.323 Voip Network-based Security Analysis

VoIP telephony or IP telephony is the transportation of voice traffic over the Internet protocol (IP). A major issue in the IP network is security. A lot of security incidents occurred in the last year sand their number is still increasing. Therefore security is an essential topic for VoIP telephony systems. As one of the most important standards of VoIP, the security of H.323 protocol and H.323 based IP-Telephony Network must also be seriously concerned.This project deals with the security of a VoIP telephony system. Its goal was to analyse and evaluate the protocols used between the entities participating in the IP telephony system. The evaluation focuses on security in the H.323 based IP-Telephony Network, and is performed from the perspective of an attacker trying to find weaknesses and risks in the network. For each type of attempt by the malicious attacker, we examined the security level and possible solutions to flaws in the system.The detail work include:1) Vulnerabilities analysis of and typical attack methods research on H.323 protocol towards it's protocol specification and implemtation.2) Typical attack methods research on key H.323 network components, such as endpoints,gatekeeper and gateway.3) Based on the above analysis, find the security solutions to H.323 protocol, to it's key components and VoIP system.The conclusion of this analysis is that the H.323 based IP-Telephony Network is exploitable, and that serious improvements are needed to achieve a satisfying level of security for the system.