Browsing by Author "Silva, Luis Moura"
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- Defeating Colluding Nodes in Desktop Grid Computing PlatformsPublication . Silaghi, Gheorghe Cosmin; Araujo, Filipe; Silva, Luis Moura; Domingues, Patrício; Arenas, Alvaro E.Desktop Grid systems reached a preeminent place among the most powerful computing platforms in the planet. Unfortunately, they are extremely vulnerable to mischief, because computing projects exert no administrative or technical control on volunteers. These can very easily output bad results, due to software or hardware glitches (resulting from over-clocking for instance), to get unfair computational credit, or simply to ruin the project. To mitigate this problem, Desktop Grid servers replicate work units and apply majority voting, typically on 2 or 3 results. In this paper, we observe that simple majority voting is powerless against malicious volunteers that collude to attack the project. We argue that to identify this type of attack and to spot colluding nodes, each work unit needs at least 3 voters. In addition, we propose to post-process the voting pools in two steps. i) In the first step, we use a statistical approach to identify nodes that were not colluding, but submitted bad results; ii) then, we use a rather simple principle to go after malicious nodes which acted together: they might have won conflicting voting pools against nodes that were not identified in step i. We use simulation to show that our heuristic can be quite effective against colluding nodes, in scenarios where honest nodes form a majority.
- Monitoring the EDGeS project infrastructurePublication . Araujo, Filipe; Santiago, David; Ferreira, Diogo; Farinha, Jorge; Domingues, Patrício; Silva, Luis Moura; Urbah, Etienne; Lodygensky, Oleg; He, Haiwu; Marosi, Attila Csaba; Gombas, Gabor; Balaton, Zoltan; Farkas, Zoltan; Kacsuk, PeterEDGeS is an European funded Framework Program 7 project that aims to connect desktop and service grids together. While in a desktop grid, personal computers pull jobs when they are idle, in service grids there is a scheduler that pushes jobs to available resources. The work in EDGeS goes well beyond conceptual solutions to bridge these grids together: it reaches as far as actual implementation, standardization, deployment, application porting and training. One of the work packages of this project concerns monitoring the overall EDGeS infrastructure. Currently, this infrastructure includes two types of desktop grids, BOINC and XtremWeb, the EGEE service grid, and a couple of bridges to connect them. In this paper, we describe the monitoring effort in EDGeS: our technical approaches, the goals we achieved, and the plans for future work.