Peer-to-peer networks are widely used today. Due to this wide use, they are the target of many attackers. The most mentionable of them is the Sybil attack. This is an attack in which it creates many fake identities. In this paper, the detection scheme and efficient mitigation mechanism to counteract Sybil attack in the peer-to-peer network is proposed. The proposed Sybil detection scheme is used to detect Sybil attack. The detection of Sybil attack is depending upon the behavior of the packets. The identity and the location of the packet are checked. If the location and identity of the packet are changed than that of the mentioned, the packet is detected as a Sybil attack. Sybil mitigation scheme is the combination of cost incurred method and certified authentication method. The Sybil packet will be removed by closing read/write operations. The proposed scheme is evaluated on the basis of detection rate and false positive rate. The experimental results show that Sybil attack is accurately detected by the proposed system in terms of low false positive rate and high detection rate. Moreover, the proposed system works efficiently in terms of Sybil detection rate and false positive rate.