Descobriment de serveis en xarxes ad-hoc : directory facilitator

Aquest projecte presenta una solució intregrada amb les especificacions de la FIPA d’un servei de pàgines grogues per a la plataforma d’agents de JADE en entorns ad hoc. El servei de pàgines grogues interaccionarà a través d’un middleware amb diferents tecnologies P2P per proporcionar als agents un servei totalment fiable i transparent que els ajudarà a superar la limitació del sistema de federacions de FIPA.

Descobriment de serveis en xarxes ad-hoc: JADE Bluetooth Discovery Middleware

En aquest projecte s'ha dissenyat i implementat un nou Discovery Middleware per a la plataforma d'agents mòbils JADE. Aquest DM col·laborarà amb el Directory Facilitator per tal d'oferir als agents un servei transparent que els permetrà descobrir serveis en plataformes remotes que siguin accessibles mitjançant xarxes ad-hoc basades en la tecnologia Bluetooth.

Xarxes ad hoc cooperatives

Estudi sobre la cooperació entre els nodes que formen una xarxa mòbil ad hoc, analitzant la distància entre aquests per conèixer la capacitat de transmissió d’informació entre el node origen i el node destí.

Preliminary study of cooperation in hybrid ad-hoc networks

In this paper, we present a first approach to evolve a cooperative behavior in ad hoc networks. Since wireless nodes are energy constrained, it may not be in the best interest of a node to always accept relay requests. On the other hand, if all nodes decide not to expend energy in relaying, then network throughput will drop dramatically. Both these extreme scenarios are unfavorable to the interests of a user. In this paper we deal with the issue of user cooperation in ad hoc networks by developing the algorithm called Generous Tit-For-Tat. We assume that nodes are rational, i.e., their actions are strictly determined by self-interest, and that each node is associated with a minimum lifetime constraint. Given these lifetime constraints and the assumption of rational behavior, we study the added behavior of the network.

Técnicas de Anonimato para Securizar Redes Móviles Ad Hoc

Las redes móviles ad hoc son redes formadas por lainterconexión de terminales inalámbricos que de manera autónoma,sin ninguna administración central, establecen enlaces decomunicación entre ellos. La infraestructura de red la componenlos propios terminales de usuarios que actúan de gestores yencaminadores de paquetes. Así, un usuario cualquiera puedeconectarse con un terminal remoto a través de una conexiónmultisalto entre diferentes usuarios. En este tipo de redes tanabiertas, uno de los retos prioritarios es proteger el anonimatode los sujetos y sus localizaciones. En este artículo hacemos unrepaso de las técnicas existentes a través de los protocolos que sehan propuesto en la literatura, y exponemos los problemas queaun quedan abiertos.

Gestión de confianza en redes ad hoc

El despliegue de un esquema de confianza es fundamental para poder desarrollar servicios de seguridad que permitan administrar y operar una red. Sin embargo, las soluciones empleadas en las redes tradicionales no se adaptan a un entorno ad hoc debido a la naturaleza dinámica y sin infraestructura de estas redes. En el presente trabajo se propone un esquema de confianza práctico y eficiente basado en una infraestructura de clave pública distribuida, umbral y jerárquica, que no requiere sincronización temporal entre todos los nodos de la red. La autorización de usuarios en el sistema se hace a través de certificados de corta duración que eliminan la necesidad de mantener la publicación y diseminación de unas listas de revocación. Por otro lado, una entidad externa de confianza permite alargar la reputación de un usuario de la red más allá de la existencia de la propia red.

On an IDS Model for Mobile Ad Hoc Networks

Manet security has a lot of open issues. Due to its character-istics, this kind of network needs preventive and corrective protection. Inthis paper, we focus on corrective protection proposing an anomaly IDSmodel for Manet. The design and development of the IDS are consideredin our 3 main stages: normal behavior construction, anomaly detectionand model update. A parametrical mixture model is used for behav-ior modeling from reference data. The associated Bayesian classi¯cationleads to the detection algorithm. MIB variables are used to provide IDSneeded information. Experiments of DoS and scanner attacks validatingthe model are presented as well.

A Fair and Secure Cluster Formation Process for Ad Hoc Networks

An efficient approach for organizing large ad hoc networks is to divide the nodesinto multiple clusters and designate, for each cluster, a clusterhead which is responsible forholding intercluster control information. The role of a clusterhead entails rights and duties.On the one hand, it has a dominant position in front of the others because it manages theconnectivity and has access to other node¿s sensitive information. But on the other hand, theclusterhead role also has some associated costs. Hence, in order to prevent malicious nodesfrom taking control of the group in a fraudulent way and avoid selfish attacks from suitablenodes, the clusterhead needs to be elected in a secure way. In this paper we present a novelsolution that guarantees the clusterhead is elected in a cheat-proof manner.

Cryptographic Energy Costs are Assumable in Ad Hoc Networks

Performance of symmetric and asymmetriccryptography algorithms in small devices is presented. Both temporaland energy costs are measured and compared with the basicfunctional costs of a device. We demonstrate that cryptographicpower costs are not a limiting factor of the autonomy of a deviceand explain how processing delays can be conveniently managedto minimize their impact.

A Forwarding Cooperation Protocol for Plain and Cluster-based Ad Hoc Networks

Peer-reviewed

What is the Problem of Ad Hoc Hypotheses?

The received view of an ad hoc hypothesis is that it accounts for only the observation(s) it was designed to account for, and so non-adhocness is generally held to be necessary or important for an introduced hypothesis or modification to a theory. Attempts by Popper and several others to convincingly explicate this view, however, prove to be unsuccessful or of doubtful value, and familiar and firmer criteria for evaluating the hypotheses or modified theories so classified are characteristically available. These points are obscured largely because the received view fails to adequately separate psychology from methodology or to recognise ambiguities in the use of 'ad hoc'.

Opportunity cost of ad hoc marine reserve design decisions: an example from South Australia

Like many states and territories, South Australia has a legacy of marine reserves considered to be inadequate to meet current conservation objectives. In this paper we configured exploratory marine reserve systems, using the software MARXAN, to examine how efficiently South Australia's existing marine reserves contribute to quantitative biodiversity conservation targets. Our aim was to compare marine reserve systems that retain South Australia's existing marine reserves with reserve systems that are free to either ignore or incorporate them. We devised a new interpretation of irreplaceability to identify planning units selected more than could be expected from chance alone. This is measured by comparing the observed selection frequency for an individual planning unit with a predicted selection frequency distribution. Knowing which sites make a valuable contribution to efficient marine reserve system design allows us to determine how well South Australia's existing reserves contribute to reservation goals when representation targets are set at 5, 10, 15, 20, 30 and 50% of conservation features. Existing marine reserves that tail to contribute to efficient marine reserve systems constitute 'opportunity costs'. We found that despite spanning less than 4% of South Australian state waters, locking in the existing ad hoc marine reserves presented considerable opportunity costs. Even with representation targets set at 50%, more than halt of South Australia's existing marine reserves were selected randomly or less in efficient marine reserve systems. Hence, ad hoc marine reserve systems are likely to be inefficient and may compromise effective conservation of marine biodiversity.

Rede P2P sobre WLANs em modo ad hoc

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores