Free-riding in BitTorrent Networks with the Large View Exploit

This paper presents an experimental study on the behavior of BitTorrent networks when selfish peers attempt to maintain high download rates without uploading. We modified a BitTorrent client so that it acquires a larger than normal view of a BitTorrent swarm and connects to all peers in its view. At the same time, the modified client does not upload any data to its peers. Our experimental results show that: a) our modified freerider client can achieve better download rates than a compliant client in most common-case public torrents; b) when the percentage of our modified free-rider clients in PlanetLab-residing torrents with ∼300 leechers is less than 40%, free-riders on average outperform compliant clients; and c) as the number of free-riders increases, both free-riders and compliant clients incur substantial performance degradation. These results suggest that the large view exploit is effective, and it has the potential for wide adoption.