Robust Sybil attack detection mechanism for Social Networks - a survey

Now a day's Recommender Systems (RS) have become predominant in Internet of Things (IoT), Online Social Networks (OSN) and Social Internet of Things (SIoT). Sybil attack is an attack where malicious users suppress opinions of honest users by creating fake identities called Sybils. Sybil attacks are prevalent in wireless sensor networks, online social networks, Peer to Peer networks and mobile networks. In this paper survey various types of Sybil attacks which are based on behavior of attacker. This paper also surveys different types of current Sybil defense protocols like SybilGuard, SybilLimit, SybilDefender, SybilInfer, SybilShield, and SyMon to defend against the Sybil attack.