Hassan Achi

Network security approach for digital forensics analysis

Advances in Digital Technology have presented new challenges to both Industry and Law. Technology security experts are enhancing platforms security to protect enterprise and government from intrusions, whereas legal experts are adopting new techniques to investigate ldquoillegalrdquo breaches to systems and networks. This paper provides an overview of Digital Forensics methodologies, computer and network vulnerabilities and security measures, forensics tracking mechanisms to detect and deter intruders. A case study for tracing a Distributed DoS attack is also presented.

Performance comparison of spread ALOHA and CDMA wireless systems

Wireless multiple access technology has grown over several decades, with new protocols being developed. Spread ALOHA has become one of the advanced techniques promising several advantages over existing conventional and spread spectrum based wireless systems. With spread ALOHA the wireless system becomes simpler, operationally flexible, higher in bandwidth and may accommodate high number of users [Dennis et al., 1997]. In this paper the performance, in terms of throughput and time delay, of spread ALOHA system as compared with code-division-multiple-access (CDMA) is analysed and evaluated in the presence of noise and interference. Mathematical expressions are derived to estimate probability of error, throughput and time delay to compare both wireless systems.

An overview of digital security forensics approach and modelling

Digital Forensics has rapidly evolved over the last decade and continues to gain significance in both the law enforcement and the scientific community. It has now become an intrinsically interdisciplinary field, and research work has been established in various areas such as information & communication technologies, law, social sciences and business administration. This paper provides an overview of Digital Forensics methodologies, modeling, analysis and applications. It also discusses some of the major technical and legal challenges in the combat of digital technology crimes.

Digital forensics of wireless systems and devices technical and legal challenges

Wireless Digital Security Forensics has been currently acknowledged as a major challenge for both technical and legal organizations; the growth of wireless networks and access devices have created more security vulnerabilities and resulted in more incidents and threats to both organizations and consumers. While there are current methodologies, techniques and tools which are utilized or being developed in this area, the challenge remains to maintain and keep up with the fast paste of the wireless growing technologies. In this paper we discuss some of the current challenges and highlight some approaches and techniques which can be used during the course of forensics investigation of wireless systems and devices.

Methodology and challenges in digital security forensics of wireless systems and devices

Wireless Digital Security Forensics has been currently acknowledged as a major challenge for both technical and legal organizations; the growth of wireless networks and access devices have created more security vulnerabilities and resulted in more incidents and threats to both organizations and consumers. While there are current methodologies, techniques and tools which are utilized or being developed in this area, the challenge remains to maintain and keep up with the fast paste of the wireless growing technologies. In this paper we discuss some of the current challenges and highlight some approaches and techniques which can be used during the course of forensics investigation of wireless systems and devices.

Performance analysis for spread ALOHA wireless systems

Spread ALOHA has emerged as an advanced wireless multiple access technology promising several advantages over existing conventional and spread spectrum based wireless systems. With spread ALOHA the wireless system becomes simpler, operationally flexible, higher in bandwidth and may accommodate high number of users (Elliot, DW & Abramson, N, 1997). In this paper the performance, in terms of throughput and time delay, of spread ALOHA system as compared with code division multiple access is analyzed and evaluated in the presence of noise and interference. Mathematical expressions are derived to estimate probability of error, throughput and time delay to compare both wireless systems.

Performance improvement of spread ALOHA systems using single code

Spread ALOHA as an advanced multiple access technique has shown several advantages over existing conventional and spread spectrum based wireless systems. Spread ALOHA is currently recognised as a simplified wireless multiple access system which provides a higher bandwidth and may accommodate high number of users. Over the last decade, several models have been developed to predict and estimate the performance of Spread ALOHA. Various combinations of protocols have been employed to enhance performance. This paper investigates the employment of a unique spreading code in conjunction with Spread ALOHA as opposed to the common method of employing distinct spreading codes for all users on the communication channel. In this paper we have modeled and simulated a Single Code Spread ALOHA (SCSA) system together with a conventional CDMA ALOHA system in order to analyse and compare the performance of both systems. Two types of PN codes were used in the simulation models, namely m-sequence and Gold codes. The simulation results showed comparable performance of both systems, and verified the suitability of m-sequence for SCSA and Gold codes for CDMA respectively.

Reducing delays for frame relay customers over FR-ATM networks

The ever-increasing implementation of frame relay (FR) over asynchronous transfer mode (ATM) backbone is leading to a considerable latency in customer services running over the network. This paper describes the process of build-up delay in a FR ATM interworking. In addition, this paper proposes a new approach to reduce the latency by increasing the PIR/SIR ratio. Furthermore, a case study is introduced in order to validate the proposed method. Finally, the burstiness, virtual bandwidth and buffer overflow affecting the network performance are discussed.

Performance Analysis of Single Code Spread ALOHA Systems

Spread ALOHA has become one of the advanced multiple access techniques promising several advantages over existing conventional and spread spectrum based wireless systems. Spread ALOHA is currently recognised as a simplified wireless multiple access system which provides a higher bandwidth and may accommodate high number of users. Over the last decade, several models have been developed to predict and estimate the performance of Spread ALOHA. Various combinations of protocols have been employed to enhance performance. This paper investigates the employment of a unique spreading code in conjunction with Spread ALOHA as opposed to the common method of employing distinct spreading codes for all users on the communication channel. In this paper we have modeled and simulated a Single Code Spread ALOHA (SCSA) system together with a conventional CDMA ALOHA system in order to analyse and compare the performance of both systems. Two types of PN codes were used in the simulation models, namely m-sequence and Gold codes. The simulation results showed comparable performance of both systems, and verified the suitability of m-sequence for SCSA and Gold codes for CDMA respectively.

Video broadcasting using switched virtual circuits over ATM network

Switched Virtual Circuits (SVC) have been a known functionality of ATM networks for years. The connection oriented and low latency nature of ATM makes it natural for handling streaming protocols such as video and multimedia. One of the advantages of SVC implementation is to provide bandwidth on demand, and reduce network complexity and costs. This paper explores the implementation of Video broadcasting services using SVC over ATM networks. A Network design based on performance tests has been proposed and Service Level Agreement is recommended.