This project is asking to implement a part of the peer-to-peer (P2P) protocol Circular DHT. A primary requirement for a P2P application is that the peers are form a connected network at all time. It is asking to implement one P2P application which has the functions of requesting files and gracefully departing the P2P circle. In this project, there not be real files to be requested, but only figure out the location of the files. Moreover, A complication that this P2P network must be able to deal with is that peers can leave the network suddenly (because there maybe a crash), then the remaining peers must try to keep a connected network without these peers. It is asked to implement this using socket programming of both TCP and UDP protocols