Detection of Network Congestion and Denial of Service (DoS) Attacks in Cognitive Radio Networks A Cognitive Radio Network (CRN) is based on a technology that enables secondary users (SUs) to access available licensed spectrum not occupied by primary users (PUs). However, due to its open and wireless nature, a CRN is vulnerable to fraudulent attacks, which might attempt to eavesdrop or modify the contents of packets being transmitted. Moreover, denying the opportunity to SUs to use a free band leads to underutilization of the spectrum space. In this context, it is most important as well as challenging to differentiate between networks under denial of service (DoS) attack from the ones experiencing congestion. This paper adopts the SUs performance measures of packet loss probability, mean queue length and mean throughput of the transmission node in order to devise a packet delivery ratio (PDR) for SUs aiming to determine whether or not the network is experiencing a DoS attack. PDR in this case is the ratio of the number of packets successfully forwarded from the encryption node to the SU transmitter. To this end, a generalized stochastic Petri net (GSPN) is proposed in order to investigate if the network is under a DoS attack and suggest a preventive strategy for an efficient network protection. Based on the application of the Mobius Petri Net Package, typical numerical simulation experiments are carried out and related operational interpretations are made.

DroPPPP: A P4 Approach to Mitigating DoS Attacks in SDN. SoftwareDefined Networking (SDN) has proven itself a useful technology for establishing and managing configurable, dynamic networks with the rapid deployment of services in the past decade. Despite these advantages, the fact that the functionality of SDN relies heavily on the controller with a much less capable data plane creates a single point of failure, which leaves the network susceptible to denial of service (DoS) attacks mainly targeting the controller to affect the operation of the whole network. An effective approach for mitigating DoS attacks in SDN requires identifying and stopping attacks as close to their source as possible, which will require involvement of the data plane in the mitigation strategy. In this work we propose DroPPPP, a DoS prevention approach for SDN that operates in the data plane using the P4 programming language. We demonstrate through experiments in the Mininet that lightweight processing of the packets in the data plane with DroPPPP negates significant overheads through reducing the traffic between switches while keeping the controllerxe2x80x99s CPU usage at 0% and below 50% during spoofing and volumetric attacks.