We study a natural and potentially devastating attack against BitTorrent, namely, attacking the initial seed in a torrent's early stages. The goal of this attack is to diminish the seed's ability to upload blocks. If the attacker can discover and react quickly enough to the new torrent, it can possibly "nip the torrent in its bud," preventing all of the leechers from obtaining the entire file. We consider two natural seed attacks: the bandwidth attack and the connection attack. We take a three-prong approach to analyze these attacks. First, we actually launch and measure the attacks using popular BitTorrent seeds (Azureus, uTorrent, and BitTornado). To this end, because we do not want to interfere with torrents in the wild, we have created our own private torrents within PlanetLab. Second, to gain insight into our empirical results, we carefully analyze the connection management and seeding algorithms in open-source BitTorrent seeds. Third, we construct a simple fluid model which provides additional insights into the empirical results. We have discovered that the three BitTorrent seeds investigated are quite resilient to such an attack. The observations and conclusions in this paper can help P2P developers design highly-resilient P2P systems.
