Network Systems (network + systems)

Distribution by Scientific Domains

Selected Abstracts

A dynamic key management solution to access hierarchy

Xukai Zou
Hierarchical access control (HAC) has been a fundamental problem in computer and network systems. Since Akl and Taylor proposed the first HAC scheme based on number theory in 1983, cryptographic key management techniques for HAC have appeared as a new and promising class of solutions to the HAC problem. Many cryptographic HAC schemes have been proposed in the past two decades. One common feature associated with these schemes is that they basically limited dynamic operations at the node level. In this paper, by introducing the innovative concept of ,access polynomial' and representing a key value as the sum of two polynomials in a finite field, we propose a new key management scheme for dynamic access hierarchy. The newly proposed scheme supports full dynamics at both the node level and user level in a uniform yet efficient manner. Furthermore, the new scheme allows access hierarchy to be a random structure and can be flexibly adapted to many other access models such as ,transfer down' and ,depth-limited transfer'. Copyright 2007 John Wiley & Sons, Ltd. [source]

Cross-layer protocol optimization for satellite communications networks: a survey

Giovanni Giambene
Abstract Satellite links are expected to be one important component of the next-generation Internet. New satellite system architectures are being envisaged to be fully IP based and support digital video broadcasting and return channel protocols (e.g. DVB-S, DVB-S2 and DVB-RCS). To make the upcoming satellite network systems fully realizable, meeting new services and application requirements, a complete system optimization is needed spanning the different layers of the OSI, and TCP/IP protocol stack. This paper deals with the cross-layer approach to be adopted in novel satellite systems and architectures. Different cross-layer techniques will be discussed, addressing the interactions among application, transport, MAC and physical layers. The impacts of these techniques will be investigated and numerical examples dealing with the joint optimization of different transport control schemes and lower layers will be considered referring to a geostationary-based architecture. Our aim is to prove that the interaction of different layers can permit to improve the higher-layer goodput as well as user satisfaction. Copyright 2006 John Wiley & Sons, Ltd. [source]

Attack,norm separation for detecting attack-induced quality problems on computers and networks

Nong Ye
Abstract Cyber attacks on computer and network systems induce system quality and reliability problems, and present a significant threat to the computer and network systems that we are heavily dependent on. Cyber attack detection involves monitoring system data and detecting the attack-induced quality and reliability problems of computer and network systems caused by cyber attacks. Usually there are ongoing normal user activities on computer and network systems when an attack occurs. As a result, the observed system data may be a mixture of attack data and normal use data (norm data). We have established a novel attack,norm separation approach to cyber attack detection that includes norm data cancelation to improve the data quality as an important part of this approach. Aiming at demonstrating the importance of norm data cancelation, this paper presents a set of data modeling and analysis techniques developed to perform norm data cancelation before applying an existing technique of anomaly detection, the chi-square distance monitoring (CSDM), to residual data obtained after norm data cancelation for cyber attack detection. Specifically, a Markov chain model of norm data and an artificial neural network (ANN) of norm data cancelation are developed and tested. This set of techniques is compared with using CSDM alone for cyber attack detection. The results show a significant improvement of detection performance by CSDM with norm data cancelation over CSDM alone. Copyright 2006 John Wiley & Sons, Ltd. [source]

EWMA techniques for computer intrusion detection through anomalous changes in event intensity

Nong Ye
Abstract Intrusion detection is used to monitor and capture intrusions into computer and network systems, which attempt to compromise the security of computer and network systems. To protect information systems from intrusions and thus assure the reliability and quality of service of information systems, it is highly desirable to develop techniques that detect intrusions into information systems. Many intrusions manifest in dramatic changes in the intensity of events occurring in information systems. Because of the ability of exponentially weighted moving average (EWMA) control charts to monitor the rate of occurrences of events based on the their intensity, we apply three EWMA statistics to detect anomalous changes in the events intensity for intrusion detections. They include the EWMA chart for autocorrelated data, the EWMA chart for uncorrelated data and the EWMA chart for monitoring the process standard deviation. The objectives of this paper are to provide design procedures for realizing these control charts and investigate their performance using different parameter settings based on one large dataset. The early detection capability of these EWMA techniques is also examined to provide the guidance about the design capacity of information systems. Copyright 2002 John Wiley & Sons, Ltd. [source]

Unpacking a Wicked Problem: Enablers/Impediments to Regional Engagement

Michael J. Christie
A case study approach is applied to review Local Government Authorities (LGA) regional engagement in the Australian context. We address the question ,What are the key LGA enablers/impediments to regional engagement?' by applying Leydesdorff's (2000) proposition that triple helix type network systems exhibit patterns of complex behaviour if the interaction factors that trigger enablers are reflexively declared. The three strands of the LGA triple helix network system are institutions, industry and government. In this case study the LGA's overall management of its regional stakeholder relationships resulted in impediments that limit strong regional engagement. Importantly, the findings inform practitioners, policy-makers and research audiences of the nature of impediments and, by inference, the nature of enablers in LGA triple helix network systems. [source]