Distributed denial of service (DDoS) attacks are ever threatening to the developers and users of the Internet. DDoS attacks targeted at the application layer are especially difficult to be detected since they mimic the legitimate users' requests. The situation becomes more serious when they occur during flash events. A more sophisticated algorithm is required to detect such attacks during a flash crowd. A few existing works make use of flow similarity for differentiating flash crowds and DDoS, but flow characteristics alone cannot be used for effective detection. In this paper, we propose a novel mechanism for discriminating DDoS and flash crowds based on the combination of the parameters reflecting their behavioral differences. Flow similarity, client legitimacy, and web page requested are identified as the principal parameters and are used together for effective discrimination. The proposed mechanism is implemented on resilient proxies in order to protect the server from direct flooding and to improve the overall performance. The real datasets are used for simulation, and the results are presented to evaluate the performance of the proposed system. The results show that the proposed mechanism does effective detection with fewer false positives and false negatives.

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Abstract:A cloud system uses virtualization technology to provide cloud resources (e.g. CPU, memory) to users in form of virtual machines. Job requests are assigned on these VMs for execution. Efficient job assignment on VMs will reduce the number of hosts used. Hence, it is essential to achieve energy optimization in cloud computing environments. Therefore, in this paper, a job scheduling mechanism is proposed to assign job to a VM of the existing active hosts itself by considering job classification and preemption. So that minimizing the number of host used in allocation intern reduces the energy consumption in the Cloud datacenter. In our proposed job scheduling algorithm, categorizing the job in to three different types and assigned based on preemption policy with the earliest available time of the resource (VM) which is attached to a host. Thereby, we reduce the energy consumption by making less number of hosts in the active state and increase the utilization of active host. Finally, we conduct simulations using CloudSim and compare our algorithm with other existing methods. Significant energy savings can be obtained depending on system loads. Energy saving is about 2% to 46% with respect to the non-energy aware algorithm, 1% to 7% than the energy aware algorithms.

<p>The password which is a more secure and valuable data should be highly protected from eavesdropper. This paper presents how password required for authentication of members of group communication is securely delivered by the source or initiator of the group. The password delivery uses zero knowledge proof and sent to the group member in an encrypted format using cipher block mode encryption. The password delivered is a One Time Password which can be used for certain amount of time in order to ensure a highly secure communication environment among the group.</p>

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