sorry bugger writes "From the article: "Peer-to-peer software applications are a network administrator's nightmare. In order to be able to exchange packets with their counterpart as directly as possible they use subtle tricks to punch holes in firewalls, which shouldn't actually be letting in packets from the outside world." More under http://www.heise-security.co.uk/articles/82481"
Mr. Cole's Axiom:
The sum of the intelligence on the planet is a constant;
the population is growing.