No description available.

No description available.

Orientador: Maria Beatriz Felgar de Toledo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-07T04:30:16Z (GMT). No. of bitstreams: 1 Viana_GiovanniBogea_M.pdf: 694479 bytes, checksum: 8f1fc7bfaffc85403fba40175dcebd16 (MD5) Previous issue date: 2006 / Resumo: Esta dissertação apresenta um modelo de transações para ambientes de computação móvel que leva em conta o dinamismo e interatividade nesse ambiente. Para lidar com o dinamismo, tanto aplicações como o gerenciador da transação e os objetos participantes de uma transação são executados como agentes e podem se mover a critério da aplicação. As responsabilidades de adaptação ao dinamismo do ambiente são divididas entre aplicações e o sistema de apoio. O sistema monitora o ambiente e envia notificações às aplicações sobre variações no ambiente. As aplicações decidem sobre as políticas para se adaptar às mudanças. Para lidar com a interatividade, as operações de uma transação podem ser submetidas passo-a-passo e o usuário pode adotar as estratégias mais adequadas conforme as necessidades da aplicação e as mudanças no ambiente / Abstract: This dissertation presents a transaction model for mobile computing environments that takes into account their dynamism and interactivity. To deal with dynamism, applications, transaction managers and participating objects are executed as agents which can move as commanded by the application. The responsabilities for adaptation are divided between the applications and the underlying system. The system monitors the environment and sends notifications to applications about variations in the environment. Applications decide about policies to adapt to changes. To deal with interactivity, operations of one transaction may be submitted step-by-step and the user is able to adopt the best strategies considering application requirements and changes in the environment / Mestrado / Mestre em Ciência da Computação

Mobile agents hold significant benefits for the rapid expansion of Internet applications and current trends in computing. Despite continued interest, the promised deployment has not taken place, indicating a need for a programming model to introduce novice mobile agent programmers to this environment/paradigm. Accordingly the research question asked was, ”Since novice mobile agent programmers1 require a paradigm shift to construct successful systems, how can they be equipped to grasp the contextual issues and gain the necessary skills within reasonable time limits?” To answer the question, a complete reference providing contextual information and knowledge of mobile agent system development was compiled. Simultaneously novices are introduced to agent orientation. A generic mobile agent system architectural model, incorporating guidelines for programming mobile agents, further provides a framework that can be used to design a mobile agent system. These two structures are presented in a knowledge base that serves as a referencing tool to unlock concepts and knowledge units to novices while developing mobile agent systems. / Computing / (M.Sc. (Computer Science))

With the fast development of wireless networks and devices, Mobile IP is expected to be used widely so that mobile users can access the Internet anywhere, anytime without interruption. However, some problems, such as firewall traversal and use of private IP addresses, restrict use of Mobile IP. The objective of this thesis is to design original schemes that can enable a mobile node at abroad to access its home network as well as the Internet securely and that can help Mobile IP to be used widely and commercially. Our solutions are secure, efficient, and scalable. They can be implemented and maintained easily. In this thesis, we mainly consider Mobile IPv4, instead of Mobile IPv6. Three research topics are discussed. In each topic, the challenges are investigated and the new solutions are presented. The first research topic solves the firewall traversal problems in Mobile IP. A mobile node cannot access its firewall-protected home network if it fails the authentication by the firewall. We propose that an IPsec tunnel be established between the firewall and the foreign agent for firewall traversal and that an IPsec transport security association be shared by the mobile node and a correspondent node for end-to-end security. The second topic researches further on firewall traversal problems and investigates the way of establishing security associations among network entities. A new security model and a new key distribution method are developed. With the help of the security model and keys, the firewall and the relevant network entities set up IPsec security associations to achieve firewall traversal. A mobile node from a private home network cannot communicate with other hosts with its private home address when it is visiting a public foreign network. A novel and useful solution is presented in the third research topic. We suggest that the mobile node use its Network Access Identifier (NAI) as its identification and obtain a public home address from its home agent. In addition, a new tunnel between the mobile node and its home agent is proposed.

Mobile agents hold significant benefits for the rapid expansion of Internet applications and current trends in computing. Despite continued interest, the promised deployment has not taken place, indicating a need for a programming model to introduce novice mobile agent programmers to this environment/paradigm. Accordingly the research question asked was, ”Since novice mobile agent programmers1 require a paradigm shift to construct successful systems, how can they be equipped to grasp the contextual issues and gain the necessary skills within reasonable time limits?” To answer the question, a complete reference providing contextual information and knowledge of mobile agent system development was compiled. Simultaneously novices are introduced to agent orientation. A generic mobile agent system architectural model, incorporating guidelines for programming mobile agents, further provides a framework that can be used to design a mobile agent system. These two structures are presented in a knowledge base that serves as a referencing tool to unlock concepts and knowledge units to novices while developing mobile agent systems. / Computing / (M.Sc. (Computer Science))

This thesis presents the developed taxonomy of the security threats in agent-based distributed systems. Based on this taxonomy, a set of theories is developed to facilitate analyzng the security threats of the mobile-agent systems. We propose the idea of using the developed security risk graph to model the system's vulnerabilties.

The mobility attribute of a mobile agent implies deployment thereof in untrustworthy environments, which introduces malicious host threats. The research question deals with how a security framework could be constructed to address the mentioned threats without introducing high costs or restraining the mobile agent's autonomy or performance. Available literature have been studied, analysed and discussed. The salient characteristics as well as the drawbacks of current solutions were isolated. Through this knowledge a dynamic mobile agent security framework was defined. The framework is based on the definition of multiple security levels, depending on type of deployment environment and type of application. A prototype was constructed and tested and it was found to be lightweight and efficient, giving developers insight into possible security threats as well as tools for maximum protection against malicious hosts. The framework outperformed other frameworks / models as it provides dynamic solutions without burdening a system with unnecessary security gadgets and hence paying for it in system cost and performance / Computing / D.Phil.

Nearly all present-day commercial intrusion detection systems are based on a hierarchical architecture. In such an architecture, the root node is responsible for detecting intrusions and for issuing responses. However, an intrusion detection system (IDS) based on a hierarchical architecture has many single points of failure. For example, by disabling the root node, the intrusion-detection function of the IDS will also be disabled. To solve this problem, an IDS inspired by the human immune system is proposed. The proposed IDS has no single component that is responsible for detecting intrusions. Instead, the intrusion-detection function is divided and placed within mobile agents. Mobile agents act similarly to white blood cells of the human immune system and travel from host to host in the network to detect intrusions. The IDS is fault-tolerant because it can continue to detect intrusions even when most of its components have been disabled. / Computer Science (School of 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)