The Research On P2P File Pollution

Since the appearance of P2P technology,file-sharing has been one of the most widely used in this area.However, with the number of users increasing,a large number of security issues about P2P networks has come up. Among them,file pollution is one of the most serious problem.File pollution has brought huge harm to both P2P systems and users.On the one hand,if P2P systems are filled with a large number of contents which do not conform to its title,the effectiveness of these systems will greatly reduce.On the other hand, when a user attempts to download a file but suffer a polluted one,he would consume bandwidth that not necessary.Moreover,if the polluted file carrys viruses,Trojan horses or other malicious programs,the user's loss would be disastrous.Therefore, anti-pollution has become an important topic.This paper has studied and discussed problems that respected to file pollution. Firstly,it shows that pollution is pervasive through analyzing the pollution condition in current P2P file-sharing systerris.Then it summaries a number of common anti -pollution methods,and points out that depending on reputation systems is the most available method.Next,this paper focuses on the behavior of attacking peers and benign peers respectively,and simulates and analyses the impact of benign peers' behavior for pollution mechanisms taken by attacking peers.Lastly,a hybrid reputation system against file pollution has been proposed.This hybrid reputation system combines the advantages of both object reputation system and peer reputation system.It introduces severe penalty strategy and polling incentive mechanism so as to remind users to delete polluted files as soon as possible. So it can prevent a further spreading of pollution contents,and isolate the attacking peers and polluted files effectively.The simulation results show that the hybrid reputation system has better anti-pollution performance than credence system.