Peer to Peer models are based on user altruism, where a user shares his content. Real life p2p systems suffer from free rider?s problem. Many nodes contribute much more than they should while others get a free ride for downloading the content. We present a simulation based study of BitTorrent like p2p systems. We propose a self punishing and self healing model that dissuades the users from cheating and encourages them to cooperate. A preferential based scheme is used to group nodes in the same stratum. This protocol uses publish based model and public key cryptography that prevents the nodes from cheating and enforces them to cooperate. Our results show that the node behavior changes from selfish to altruistic. Our proposed model ensures fairness, performs better in link utilization and minimizes the mean download time.