A Survey on Defense Mechanism for Sybil Attacks in Large Social Networks

Abstract

A social network is a social structure that is made up of nodes which represents the individuals or associations. The Sybil attacks are more vulnerable that affects the Peer-to-Peer and other decentralized systems. The Sybil identities cooperate the system and pollute the system with false information. Sybil identities can restrain the honest identities in a various tasks including online content ranking, distributed hash table routing, file sharing system, reputation systems and Byzantine failure defenses. With Sybil nodes comprising a large fraction of the nodes in the system, the malicious user is capable to “out vote†the honest users, effectively breaking prior defenses against malicious behaviors. Therefore, an effectual defense mechanism against Sybil attacks would remove a primary practical obstruction to collaborative tasks on peer-to-peer (p2p) and other decentralized systems. To defend against Sybil attacks, to monitor each nodes historical behavior is often insufficient because Sybil nodes can behave nicely initially and then launch an attack. To mitigate the Sybil attacks, different decentralized mechanisms are used such as Sybil Infer, Sybil Guard, and Sybil limit to decide whether a suspect node is Sybil. In particular, we analyze the mechanisms how the Sybil attacks can be mitigated.