The Open Proxy Problem, a PowerPoint/PDF presentation shown at the Internet2 Members Meeting of April 9th 2003, by Joe St Sauver, Ph.D (Director, User Services and Network Applications University of Oregon Computing Center).
Well worth a read if you’re interested in network security or spam. Joe’s done an astonishing job of researching every angle of the issue, from historical comparisons to ‘blue boxes’ circa 1971, the status of proxy servers to the Chinese government, and even a statistical analysis of proxy DNSBL overlap. (BTW, did you know that the New York Times was broken into via an open proxy?)