New Scientist reports on P2P network studies:

A US bill proposed in July 2002 would give copyright holders the legal power to attack the computers of file sharers suspected of piracy. Experts say it would be relatively easy to log on to a network and deliberately overload suspected users with fake requests for a file, by misinforming other "nodes". This is similar to overloading a web site with fake traffic in a "denial of service" attack.

But Neil Daswani and Hector Garcia-Molina of the Database Research Department at Stanford University in the US believe it may be possible to redesign peer-to-peer networks to protect them against such attacks. Daswani says this may also guard these networks against malicious computer hackers. He told New Scientist: "We were interested in both protecting the network from being shut down and protecting individual users."


Flood gates


Daswani and Garcia-Molina mathematically modeled the popular open source network Gnutella and experimented with different combinations of existing rules for efficiently sharing file requests across a network. This network consists of ordinary users, or "nodes" and "supernodes", which have higher bandwidth. Requests are broadcast between nodes and supernodes with little discrimination.

Daswani points out that anyone can join a peer-to-peer network, so it cannot be run on trust. Instead, the researchers gave each node a set of simple rules to follow when processing requests from other peers. They found that when requests from ordinary nodes were treated in a different way to requests from supernodes the damage caused by a flooding attack was dramatically reduced.