Peer-to-Peer Networks

The realization that centralized networks are not robust to attack (be it legal or technical) has spurred much of the innovation in peer-to-peer networking and file sharing technologies. In this section, we examine architectures that have evolved. Early systems were flawed because critical components remained centralized (Napster) or because of inefficiencies and lack of scalability of the protocol (gnutella). It should be noted that the problem of object location in a massively distributed, rapidly changing, heterogeneous system was new at the time peer-to-peer systems emerged. Efficient and highly scalable protocols have been proposed since then.

Napster

Napster was the service that ignited peer-to-peer file sharing in 1999. There should be little doubt that a major portion of the massive (for the time) traffic on Napster was of copyrighted objects being transferred in a peer-to-peer model in violation of copyright law. Napster succeeded where central servers had failed by relying on the distributed storage of objects not under the control of Napster. This moved the injection, storage, network distribution, and consumption of objects to users.

However, Napster retained a centralized database with a searchable index on the file name. The centralized database itself became a legal target.  Napster was first enjoined to deny certain queries (e.g. “Metallica”) and then to police its network for all copyrighted content.  As the size of the darknet indexed by Napster shrank, so did the number of users.  This illustrates a general characteristic of darknets: there is positive feedback between the size of the object library and aggregate bandwidth and the appeal of the network for its users.

Gnutella

The next technology that sparked public interest in peer-to-peer file sharing was Gnutella. In addition to distributed object storage, Gnutella uses a fully distributed database described more fully in. Gnutella does not rely upon any centralized server or service – a peer just needs the IP address of one or a few participating peers to (in principle) reach any host on the Gnutella darknet.  Second, Gnutella is not really “run” by anyone: it is an open protocol and anyone can write a Gnutella client application. Finally, Gnutella and its descendants go beyond sharing audio and have substantial non-infringing uses. This changes its legal standing markedly and puts it in a similar category to email. That is, email has substantial non-infringing use, and so email itself is not under legal threat even though it may be used to transfer copyrighted material unlawfully.