Collaborative detection and mitigation of DDoS in software-defined networks

The Journal of Supercomputing - This research presents the detection and mitigation of distributed denial of service (DDoS) in software defined networks (SDN). The proposed method consists of three...     

Targeting spam control on middleboxes: Spam detection based on layer-3 e-mail content classification

This paper proposes a spam detection technique, at the packet level (layer 3), based on classification of e-mail contents. Our proposal targets spam control implementations on middleboxes. E-mails are first pre-classified (pre-detected) for spam on a per-packet basis, without the need for reassembly. This, in turn, allows fast e-mail class estimation (spam detection) at receiving e-mail servers to support more effective spam handling on both inbound and outbound (relayed) e-mails. In this paper, the naïve Bayes classification technique is adapted to support both pre-classification and fast e-mail class estimation, on a per-packet basis. We focus on evaluating the accuracy of spam detection at layer 3, considering the constraints on processing byte-streams over the network, including packet re-ordering, fragmentation, overlapped bytes, and different packet sizes. Results show that the proposed layer-3 classification technique gives less than 0.5% false positive, which approximately equals the performance attained at layer 7. This shows that classifying e-mails at the packet level could differentiate non-spam from spam with high confidence for a viable spam control implementation on middleboxes.     

Improved quantum circuit modelling based on Heisenberg representation

Heisenberg model allows a more compact representation of certain quantum states and enables efficient modelling of stabilizer gates operation and single-qubit measurement in computational basis on classical computers. Since generic quantum circuit modelling appears intractable on classical computers, the Heisenberg representation that makes the modelling process at least practical for certain circuits is crucial. This paper proposes efficient algorithms to facilitate accurate global phase maintenance for both stabilizer and non-stabilizer gates application that play a vital role in the stabilizer frames data structure, which is based on the Heisenberg representation. The proposed algorithms are critical as maintaining global phase involves compute-intensive operations that are necessary for the modelling of each quantum gate. In addition, the proposed work overcomes the limitations of prior work where the phase factors due to non-stabilizer gates application was not taken into consideration. The verification of the proposed algorithms is made against the golden reference model that is constructed based on the conventional state vector approach.     

Analysis of reinforced concrete coupled shear wall structures

The ultimate strength analysis of reinforced concrete coupled shear walls with one or two bands of openings requires a two‐stage approach. In the first stage, the analysis of the coupling beams is carried out. This is followed by the analysis of the complete wall in the second stage. A simple approach based on the ‘total moment concept’ for the analysis of coupled shear walls with one or two bands of openings is presented. Experimental results supporting the predictions of the mode of failure and ultimate strength is also presented. This study updates previous research and enhances further understanding of the behaviour of reinforced concrete shear wall structures at ultimate limit states of loading. Copyright © 1999 John Wiley & Sons, Ltd.     

A spam rejection scheme during SMTP sessions based on layer-3 e-mail classification

This paper proposes a scheme that rejects spam e-mails during their simple mail transfer protocol (SMTP) sessions. This scheme utilizes a layer-3 e-mail classification technique, which allows e-mail classes to be estimated before the end of SMTP sessions at receiving e-mail servers. We analyze the proposed scheme using discrete-time Markov chain analysis under varying e-mail traffic loads and service capacities. This paper also considers the effects of e-mail retransmission and illegal spam relaying by zombie systems on the performance of the proposed scheme. Results from our analysis show that e-mail server loading decreases by using the proposed technique. This allows the reduction in non-spam e-mail queuing delays and loss probability. Our scheme also protects e-mail servers from being overloaded by spam traffic and, if performed collectively over the Internet, it is capable of performing outbound spam control.     

Comparative experimental study of full‐scale H‐subframe using a new industrialized building system and monolithic reinforced concrete beam‐to‐column connection

Industrialized building system (IBS) is a construction process that uses techniques, products, components or building systems that involve prefabricated components and on‐site installation. The structural behaviour of a prefabricated frame structure is widely affected by the specifications of the beam‐to‐column connection. The understanding on the real behaviour of a connection can be assessed by conducting full‐scale experimental tests. In this study, a new IBS hybrid steel–concrete connection in a full‐scale H‐subframe under monotonic loading is investigated. This innovative connection system, consists of precast concrete beam‐and‐column elements with embedded steel end connectors, is patented as Smart IBS. This paper reports the testing procedures and results of this semi‐rigid IBS beam‐to‐column connection to obtain the important attributes of the connection as well as its comparison with monolithic cast‐in‐place reinforced concrete model. The height of both H‐subframes is 3.3 m while the free length of the beam is 3.2 m. The incremental loads were applied as two point loads in one‐third and two‐third of the beam length. The characteristic relationships of the connection such as load to mid‐span deflection, strength, stiffness, ductility, failure modes and crack patterns are studied and compared between both structural systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Online NetFPGA decision tree statistical traffic classifier

Classifying online network traffic is becoming critical in network management and security. Recently, new classification methods based on analysis of statistical features of transport layer traffic have been proposed. While these new methods address the limitations of the port based and payload based traffic classification, the current software-based solutions are not fast enough to deal with the traffic of today’s high-speed networks. In this paper, we propose an online statistical traffic classifier using the C4.5 machine learning algorithm running on the NetFPGA platform. Our NetFPGA classifier is constructed by adding three main modules to the NetFPGA reference switch design; a Netflow module, a feature extractor module, and a C4.5 search tree classifier. The proposed classifier is able to classify the input traffics at the maximum line speed of the NetFPGA platform, i.e. 8 Gbps without any packet loss. Our method is based on the statistical features of the first few packets of a flow. The flow is classified just a few micro seconds after receiving the desired number of packets.     

Collaborative Detection and Mitigation of Distributed Denial-of-Service Attacks on Software-Defined Network

Mobile Networks and Applications - This paper presents a collaborative technique to detect and mitigate Distributed Denial-of-Service (DDoS) flooding attacks on Software-Defined Network (SDN). This...     

Prioritized e‐mail servicing to reduce non‐spam delay and loss: A performance analysis

This paper proposes a prioritized e‐mail servicing on e‐mail servers to reduce the delay and loss of non‐spam e‐mails due to queuing. Using a prioritized two‐queue scheme, non‐spam e‐mails are queued in a fast queue and given higher service priority than spam e‐mails that are queued in a slow queue. Four prioritized e‐mail service strategies for the two‐queue scheme are proposed and analyzed. We modeled these four strategies using discrete‐time Markov chain analysis under different e‐mail traffic loads and service capacities. Non‐spam e‐mails can be delivered within a small delay, even under heavy e‐mail loadings and high spam‐to‐non‐spam a priori. Results from our analysis of the two‐queue scheme show that it gives non‐spam delay and loss probability two orders of magnitude smaller than the typical single‐queue approach during heavy spam traffic. Moreover, prioritized e‐mail servicing protects e‐mail servers from spam attacks. Copyright © 2007 John Wiley & Sons, Ltd.