Abstract:
VoIP (Voice over Internet Protocol) is a technology that allows standard telephone voice signals to be compressed into data packets for transmission over the Internet or other IP network. VoIP is a combination of various protocols, integrated together to provide voice communication over internet or intranet environment. It offers higher flexibility and more features than traditional telephony (Public Switched Telephone Network (PSTN)) infrastructures, as well as the potential for lower cost and flexibility for consumer market. Because of these advantages, VoIP technology is rapidly evolving and is being integrated into many corporate and enterprises as a substitute or as a redundancy providing medium with PSTN. Session Initiation Protocol (SIP) is the corner stone of VoIP architecture; on the basis of it entire structure is VoIP communication infrastructure is created. Because of complexities of integration of different protocols and vulnerabilities of SIP VoIP systems have a greater potential for exploitation. Biggest threat to VoIP systems implementation in corporate or military environment at present is unavailability/interruption of service commonly termed as DOS. This research aims at studying and analyzing the VoIP security concerns with specific emphasis on SIP and identifying loopholes in security leading to DOS and on this basis a security framework is proposed to detect and prevent DOS attacks.
Proposed architecture in this thesis involves use of Access Control List (ACL) and CAPTCHA challenge-response mechanism to authenticate users on the network and thus prevent DOS. Simulation of architecture is prepared to test the efficiency and usability of this combination. Analysis of this architecture is discussed in detail to propose and devise a DOS free environment in VoIP systems.
