Characterizing digital media exchanges in a university campus network

This article presents findings from a large-scale quantitative assessment of online exchanges of copyrighted material on a college campus based on network data collected using deep packet inspection (DPI). We find that use of Peer-to-Peer (P2P) for the transfer of copyrighted content is widespread on campus, although observed P2P is declining. In a month-long monitoring period in Spring 2008, at least 40% of students living on campus were observed engaging in P2P, 70% of those were detected attempting to transfer copyrighted content, and each of the latter was observed transferring copyrighted titles at an average rate of 4 titles per day. Nevertheless, from Spring 2007 to Spring 2008, the daily percentage of detected P2P users fell 10%, and the daily percentage of users observed attempting to transfer copyrighted content out of those detected doing P2P fell 20%. These changes could be the result of decreasing use of P2P, or increasing use of encrypted P2P to evade detection. We also find that, given a couple weeks or more, current DPI technology identifies most users attempting to transfer copyrighted material, out of users whose P2P traffic it can detect. This shows that even if DPI does not detect every transfer of copyrighted material, it can effectively identify individuals who make these transfers, provided they do not use encryption. However, detection of copyrighted content is less accurate for video than for audio, so it may take far longer to identify individuals who use P2P to transfer copyrighted video but not copyrighted audio. Finally, to shed light on the impact of P2P on sales of content, we find that 22% of P2P users also purchase content from the iTunes Store (iTS), each buying on average about as much content as non- P2P users who purchase from the iTunes Store. This refutes the hypothesis that all P2P users view the ability to obtain free content from P2P as a complete substitute for paying for content. On the other hand, we also find that among iTs users, those who use P2P are somewhat more likely than those do not use P2P to access iTs only for the free samples.