Voice over Internet Protocol (VoIP) is a family of technologies for the transmission of voice over Internet. Voice is converted into digital signals and transmitted as data packets. The Session Initiation Protocol (SIP) is an IETF protocol for VoIP and other multimedia. SIP is an application layer protocol for creating, modifying and terminating sessions in VoIP communications. Since SIP is a more flexible and simple protocol, it is quite easy to add features to it. Distributed Denial of Service Attack (DDoS) floods the server with numerous requests from various hosts. Hence, the legitimate clients will not be able to get their intended services. A major concern in VoIP and almost in all network domains is availability rather than data consistency. Most of the surviving techniques could prevent VoIP network only after collision. This paper proposes a Recurrence Quantification based approach to detect and prevent VoIP from a DDoS attack. This model detects the attack at an earlier stage and also helps to prevent from further attacks. In addition, this techniques enables the efficient utilization of resources. QUALNET has been used to simulate the operation of the proposed technology.

Distributed Denial of Service (DDoS) is a type of attack in the application layer initiated from the various hosts to a single web server. The aim of this attack is to consume all the resources of the targeted system by exploiting the vulnerability. We proposed a mathematical model called Recurrence Quantification Analysis (RQA) for detecting the DDoS attacks by computing entropy and determinism of selected packet attributes. To detect the anomalies and check the performance we considered the live traffic traces from the network and various RQA parameters like entropy, laminarity and determinism were used to determine the uncertainty or randomness in the dataset.