Securing VoIP Networks: Threats, Vulnerabilities, and Countermeasures

Chapter 6. Media Protection Mechanisms

Any multimedia application—such as video, voice, or gaming—uses a distinct set of protocols to set up sessions between end points (for example, SIP, H.323) and a distinct protocol to transmit the media streams. The standard protocol used to exchange media streams is RTP¹ (Real Time Protocol), which is defined in RFC 3550. As discussed in Chapter 3, “Threats and Attacks,” RTP streams can be intercepted and manipulated in order to perform various attacks. Although IPSec can be used to protect RTP, its limitations require a more scalable and versatile solution that alleviates the NAT traversal issue, dynamic allocation of sessions,² and the need for a PKI. This has led to the development of SRTP³ (Secure Real ...