Thursday, August 21, 2008


A Free Riding BitTorrent Client

BitThief is an ongoing project of the Distributed Computing Group at ETH Zurich.

The project deals with incentive problems in peer-to-peer filesharing systems. The lack of incentives to upload potentially results in a total collapse of the network, implying that it is essential for a completely decentralized system to incorporate protocols that ensure a fair sharing of resources. We developed a BitTorrent client that free rides on BitTorrent, that is, it downloads from BitTorrent swarms without contributing any resources itself which illustrated that the BitTorrent protocol currently fails to prevent uncooperative behavior as it does not provide any countermeasures against free riding clients.

We argue that the BitTorrent protocol has to be modified in order to effectively prevent selfishness.

Our proof-of-concept client BitThief is a byproduct of our HotNets-V paper "Free Riding in BitTorrent is Cheap".

Note that, as it is a scientific project, we require measurements of the performance of our exploits. For that purpose, the client occasionally transmits data to our webserver. The transmitted data merely contains information about the time required to download files of any size. In particular, only a hash of the info hash is transmitted, which means that it is not feasible to determine what has actually been downloaded which is not of our concern. However, we advice all testers not to download any copyrighted material.

Download your BitThief here:

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