An adaptive membership protocol against sybil attack in unstructured P2P networks

A Sybil attack refers to a network attack against identify in which a malicious user obtains multiple fake identities and creates fake nodes which are inserted amongst honest nodes in the system simultaneous. By controlling a large percentage of the system, or a large section of the local scope, the malicious user can take further boring actions like DDos attacks, False Voting, Invalid DHT routing, identifying worm spam and so on. This type of network instrusion is often found in Peer-to-Peer (P2P) and other decentralized, distributed systems. It can be difficult to predict or defend the Sybil Attack due to the open and anonymous in P2P networks. Although it is possible to identify some sybil nodes or edges, one must consider the critical case where some of the sybil nodes may have left the network prior to search, and as a result of churn attack is not prevented. In this paper, the authors present a novel protocol with a positive communication policy among peers and adaptive neighbour montoring and maintenance scheme to counter sybil, preventing malicious nodes and maintaining desirable properties such as a low network diameter and clustering. The protocol is resilient against the Sybil and Churn attacks, and is particularly suitable for information dissemination and files sharing in unstructured P2P systems.