Thesis (M.S.)--Georgia State University, 2005. / Title from title screen. Raj Sunderraman, committee chair; Anu G. Bourgeois, Yanqing Zhang, committee members. Electronic text (92 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed May 25, 2007. Includes bibliographical references (p. 57-58).

Grades oportunistas são ambientes distribuídos que permitem o aproveitamento do poder de processamento ocioso de recursos computacionais dispersos geograficamente em diferentes domínios administrativos. São características desses ambientes a alta heterogeneidade e a variação na disponibilidade dos seus recursos. Nesse contexto, o paradigma de agentes móveis surge como uma alternativa promissora para superar os desafios impostos na construção de grades oportunistas. Esses agentes podem ser utilizados na construção de mecanismos que permitam a progressão de execução das aplicações mesmo na presença de falhas. Esses mecanismos podem ser utilizados isoladamente, ou em conjunto, de forma a se adequar a diferentes cenários de disponibilidade de recursos. Neste trabalho, descrevemos a arquitetura do middleware MAG (Mobile Agents for Grid Computing Environment) e o que ele pode fazer em ambientes de grades oportunistas. Utilizamos esse middleware como base para a implementação de um mecanismo de tolerância a falhas baseado em replicação e salvaguarda periódica de tarefas. Por fim, analisamos os resultados obtidos através de experimentos e simulações. / Opportunistic grids are distributed environments built to leverage the computacional power of idle resources geographically spread across different administrative domains. These environments comprise many charateristics such as high level heterogeneity and variation on resource availability. The mobile agent paradigm arises as a promising alternative to overcome the construction challenges of opportunistic grids. These agents can be used to implement mechanisms that enable the progress on the execution of applications even in the presence of failures. These mechanisms can be combined in a flexible manner to meet different scenarios of resource availability. In this work, we describe the architecture of the MAG middleware (Mobile Agents for Grid Computing Environment) and what it can do in an opportunistic grid environment. We use this middleware as a foundation for the development of a fault tolerance mechanism based on task replication and checkpointing. Finally, we analize experimental and simulation results.

Context: Mobile agents are considered quite challenging and provide scope for developing innovative applications in distributed computing domain. One important area where there is a scope to employ mobile agents successfully is the Network security domain. There are plethora of mobile agent based security mechanisms proposed till now. But the successful deployment of the security mechanism is effected by the parameters like performance, efficiency, ability to identify the intruders, and the models vulnerability to direct attacks and so-on which make the successful deployment of the mobile agents in the security domain more challenging. Therefore it’s often demanding to identify a security mechanism that entails the performance by making use of the mobile agents in the security domain on the contrary the mechanism need to be generic and support all kinds of the environments. As a result performing vulnerability analysis in mobile agent security domain is often required. Objectives: The main objective of this study is to provide the report that incorporates the empirical analysis of the selected mobile agent based security mechanism from the perspective of performance that could be useful in defining the standards for development of the security modules for mobile agents. The secondary aim of this study is to characterize the issues related to the performance of the security mechanism in the mobile agents environment. And finally to identify the model specific barriers that will effect the performance of the security mechanism for mobile agents. Methods: This thesis performs the vulnerability analysis on the selected mobile agent based security mechanism and uses a direct implementation method to study the performance of the security mechanism. The factors considered from the performance perspective are the round trip time or can also be termed as total response time. The effect of the performance is studied with respect to the scalability of the network parameters like the number of packets and the size of the network. This thesis focuses on implementing four different modules which are individual agents communicating with each other in the network when deployed while performing a combing on the network for vulnerabilities. The four different modules implemented in the thesis are the Information Gathering Agent, Tracing Agent, Manager or Managing agent, Monitor or Monitoring agent. The performance of the mechanism is studied in three phases. The agents of the selected mechanism are implemented in the first phase and in the second phase a shear testing is done on those implemented agents of the security mechanism by collecting the round trip times of the agents as a whole with respect to the number of increasing packets (with a % increase in the number of illegitimate packets and also with the change in the number of nodes). A close monitoring on the model for the performance is performed to identify the pit falls of the model. Finally in the third phase the collected results are analyzed and presented as a set of findings from this study. Results: The results collected from this experimental study are analyzed from the motive that the security mechanism is being monitored from the perspective of identifying as many intrusions efficiently as an elusive goal rather than identifying as many intrusions precisely. The results from this thesis prove that the mechanism considered is more efficient rather than precise. Even though the results obtained from this study can be seen as efficient but there is a set of residue packets which takes a bit more time than the other packets as can be seen when one progresses the results from top to bottom this is primarily because of the factors associated with the inter networking environment like the network traffic with respect to the size of the network or the number of nodes in the network. Conclusions: After analyzing the results and providing the answers to the research questions, a conclusion can be made that the selected security mechanism is proved efficient rather than precise. This mechanism is proved to be useful only to reduce the number of intruders in the networking domain. On the contrary the mechanism also helps the deployment of the security mechanism easy this is because the advantage associated with the selected security mechanism which uses the less number of agents.

Computer Supported Cooperative Work (CSCW) is the study of how people use technology, with relation to hardware and software, to work together in shared time and space. Mobile office environments are becoming commonplace. Workers form virtual online communities on a global scale and use groupware to collaborate and complete a common goal. We tend to be mobile, yet need to be available to collaborate. This thesis investigates a protocol for our decentralized artifact control system, Nomad. Nomad enables globally dispersed members of small casually connected communities to share artifacts which are gathered on a best effort approach. The Nomad protocol takes into consideration the work habits of users and their variety of devices. The major contribution of this thesis is a simulator of the Nomad protocol, which serves as a proof-of-concept for its design. Specifically, we look at how such a protocol handles casually connected small communities. We consider high level aspects such as setting up the community, the overhead of nodes, availability, scalability and connectivity. We demonstrate scenarios that the protocol will need to handle. Furthermore, we take a broad look at CSCW, push and pull technologies, peer-to-peer technologies, and enabling technologies such as Microsoft .Net. These form the basis of the Nomad design. In addition, we suggest the integration of mobile agents, which we consider a future addition to Nomad. It was found that the protocol had to compensate for two nodes that were never online at the same time. In the case that a best effort approach is not feasible, we propose alternate approaches at the cost of overhead on a propagation node. The developed concept provided valuable insight into the problem domain, outlined the boundaries of the protocol and provided a possible solution for Nomad. The simulator proved to be a useful tool for determining outcomes from possible scenarios. The results from the simulator will feed directly into the development of Nomad. / Dissertation (MSc (Computer Science))--University of Pretoria, 2007. / Computer Science / unrestricted

O objetivo principal do presente trabalho é apresentar uma proposta que permita a combinação entre uma solução de captura de pacotes já existente e não muito flexível (sniffer) e o conceito de agentes móveis para aplicação em redes segmentadas. Essa pesquisa possui como foco principal a aplicação da técnica captura de pacotes em SDIs network based, utilizando para isso o modelo desenvolvido no ICMC (Cansian, 1997) e posteriormente adequado ao ambiente de agentes móveis (Bernardes, 1999). Assim sendo, foi especificada a camada base do ambiente desenvolvido em (Bernardes, 1999) visando as interações entre seus agentes e o agente de captura de pacotes. / The main objective of the current work is to present a proposal that allows the combination between an existent and not so flexible packet capture solution (sniffer) and the concept of mobile agents for application in switched networks. This research focuses the application of the packet capture technique in IDSs network-based, using for this purpose the model developed at ICMC (Cansian, 1997) and later adjusted to the mobile agents environment (Bernardes, 1999). Therefore, the base layer of the developed environment (Bernardes, 1999} was specified focusing the interactions between its agents and the packet capture agent.

Em decorrência do aumento do número de ataques de origem interna, a utilização de mecanismos de proteção, como o firewall, deve ser ampliada. Visto que este tipo de ataque, ocasionado pelos usuários internos ao sistema, não permite a localização imediata, torna-se necessário o uso integrado de diversas tecnologias para aumentar a capacidade de defesa de um sistema. Desta forma, a introdução de agentes móveis em apoio a segurança computacional apresenta-se como uma solução natural, uma vez que permitirá a distribuição de tarefas de monitoramento do sistema e automatização do processo de tomada de decisão, no caso de ausência do administrador humano. Este trabalho apresenta uma avaliação do uso do mecanismo de agentes móveis para acrescentar características de mobilidade ao processo de monitoração de intrusão em sistemas computacionais. Uma abordagem modular é proposta, onde agentes pequenos e independentes monitoram o sistema. Esta abordagem apresenta significantes vantagens em termos de overhead, escalabilidade e flexibilidade. / The use of protection mechanisms must be improved due the increase of attacks from internal sources. As this kind of attack, made by internal users do not allow its immediate localization, it is necessary the integrated use of several technologies to enhance the defense capabilities of a system. Therefore, the introduction of mobile agents to provide security appears to be a natural solution. It will allow the distribution of the system monitoring tasks and automate the decision making process, in the absence of a human administrator. This project presents an evaluation of the use of mobile agents to add mobile capabilities to the process of intrusion detection in computer systems. A finer-grained approach is proposed, where small and independent agents monitor the system. This approach has significant advantages in terms of overhead, scalability and flexibility.

The progress in the field of computer networks and Internet is increasing with tremendous volume in recent years. This raises important issue with regards to security. Several solutions emerged in the past which provide security at host or network level. These traditional solutions like antivirus, firewall, spy-ware, and authentication mechanisms provide security to some extends, but they still face the challenge of inherent system flaws, OS bugs and social engineering attacks. Recently, some interesting solution emerged like Intrusion Detection and Prevention systems, but these too have some problems, like detecting and responding in real time, because they mostly require inputs from system administrator. Optimistically, we have succeeded in protecting the hosts to some extent by applying the reactive approach, such as antivirus, firewall and intrusion detection and response systems, But, if we critically analyze this approach, we will reach the conclusion that it has inherent flaws, since the number of penetrations, Internet crime cases, identity and financial data thefts, etc. are rising exponentially in recent years. The main reason is that we are using only reactive approach, i.e. protection system is activated only when some security breach occurs. Secondly, current techniques try to fix the overall huge problem of security using only small remedies (firewall, antivirus and intrusion detection and preventions system) – “point solutions”. Therefore, there is a need to develop a strategy using Mobile Agents in order to operate in reactive and proactive manners, what requires providing security on the principle of defense in depth. So, that ultimate goal of securing a system as a whole can be achieved. System is assumed to be secure if unauthorized access (penetrations) is not possible and system is safe against damages. This strategy will include three aspects: (a) autonomously detect vulnerabilities on different hosts (in a distributed network) before an attacker can exploit (b) protect hosts by detecting attempts of intrusions and responding to them in real time; and finally (c) perform tasks related to security management.

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The availability of numerous mobile agent systems with its own strengths and weaknesses poses a problem when deciding on a particular mobile agent system. In this dissertation, factors based on mobility, communication and security of the mobile agent systems are presented and used as a means to address this problem. To facilitate in the process of selection, a grouping scheme of the agent system was proposed. Based on this grouping scheme, mobile agent systems with common properties are grouped together and analyzed against the above-mentioned factors. In addition, an application was developed using the Aglet Software Development Toolkit to demonstrate certain features of agent mobility, communication and security. / Theoretical Computing / M. Sc. (Computer Science)

The availability of numerous mobile agent systems with its own strengths and weaknesses poses a problem when deciding on a particular mobile agent system. In this dissertation, factors based on mobility, communication and security of the mobile agent systems are presented and used as a means to address this problem. To facilitate in the process of selection, a grouping scheme of the agent system was proposed. Based on this grouping scheme, mobile agent systems with common properties are grouped together and analyzed against the above-mentioned factors. In addition, an application was developed using the Aglet Software Development Toolkit to demonstrate certain features of agent mobility, communication and security. / Theoretical Computing / M. Sc. (Computer Science)