Research And Application Of DHT-Based P2P File Sharing

P2P is one of the most popular techologies in recent years.It has developed rapidly in the field of VoIP downloading,streaming media and coordinated computing.P2P is considered as one of four technologies affecting internet mostly by Fortune.It embodies the most fundamental value of the Internet-free.P2P is opposed to C/S,with the purpose of easing the burden of server and taking full advantage of every node.However,a lot of P2P applications still depend on central servers.Before the communications of peer to peer,a node must connect to a server first in order to get some necessary information.This thesis works at server-dependent issue using P2P searching technology.It mainly studies P2P network models,file sharing protocols,Distributed Hash Table,Kademlia and libtorrent library.This thesis discusses the development of a file sharing system with DHT technology,which helps us get rid of the constraint of Tracker.The research includes analysing the metafile parsing,connection settings,request message among nodes. KRPC and Kademlia.Kademlia has some advantages,such as simple implemention, efficient lookup,accurate resource location which assures that resource will be found if it exists.Thus,Kademlia makes up for a deficiency of Gnutella.The mode of file sharing of this system is using Tracker+DHT.This will effectively reduce the burden of the server and continue providing services even if the server is broken down.The system can also limit half-open connections and add addresses of Tracker in order to reduce the impact of system overhead and get more nodes.The system has been tested in a real environment,and the result shows that DHT could replace central server and return more nodes.