Interesting research reported on SlashDot: Tracking a Specific Machine Anywhere On The Net http://it.slashdot.org/article.pl?sid=05/03/04/1355253 http://www.zdnet.com.au/news/security/0,2000061744,39183346,00.htm Remote physical device fingerprinting http://www.caida.org/outreach/papers/2005/fingerprinting