The Study Of EMule Overlay Network

As the most popular file-sharing P2P application in the world, eMule owns millions of users and billions of files, and the number of on line users at the same time can reach more than one million. Besides, eMule not only supports the eDonkey network which is inherited from eDonkey, but also supports a new Kademlia protocol based DHT network– Kad network, which is the first largely deployed DHT network.This paper focus on eMule system, the main research aspects are the principle of eMule system, the distribution of resources in eMule system, the performance and robustness of Kad network, the security of eMule system.By the Kad network, we not only crawle down the basic information of the eMule nodes, but also crawle down the neighborship between the nodes, which is used to reproduce the topology of the Kad network. Based on the data we crawled, we find that the resources in eMule system are not distributed uniformly. We discovered the non-uniform distributions of eMule system in many aspects, such as region, IP address, file type, file size, amount of copies for different files and amount of files each user shares. The distribution of amount of copies for different files and the distribution of amount of files each user shares are similar to Zipf distritbution at main body, but quite different at head and tail. Besides, we find the Kad network is a high performance and robust network, which can work well even 30% of the total clients leave the network. We also find a flaw in the eMule system, we discuss the potential attacks for this flaw and provide two ways to fix this flaw.