Transmissão de mídia contínua ao vivo em P2P: modelagem, caracterização e implementação de mecanismo de resiliência a ataques

P2P live streaming applications are becoming more popular each day. In contrast to the client-server model, the P2P model overcomes problems like system scalability and need of powerful resources in a single point. On the other hand, P2P networks may suffer with attacks and opportunistic behavior. In this work we present a decentralized reputation system to fight attacks in P2P live streaming networks. In particular, we focus on pollution attacks, where a malicious peer alters or forges the streaming data, aiming to disseminate undesirable content. Our results include a formal model to check pollution attacks damages to P2P live streaming systems. We show that protocol and algorithms influence the impact caused by an attack. We also characterize the client behavior in P2P live streaming systems. Thus, we can understand client dynamics and evaluate the impact that it causes on system scalability and media quality. Finally we implement a reputation mechanism to fight pollution attacks. Our results show that the new mechanism can block a pollution attack with an overhead lower than 2% of network bandwidth, while the solution recommend needs at least 100%. Moreover, the new mechanism can lead with collusion attacks. In this case, it needs a peak less than 30%, while traditional approach needs at least 100% more bandwidth. Finally, allows peers rehabilitation and provides incentive mechanisms.