Those pesky NATs [network address translators]

Whether buried deep inside ISPs, or camouflaged as DSL routers, network address translators (NATs) have become a ubiquitous tool in the Internet landscape. NATs enable telco and cable operators to prevent commercial use of consumer accounts. They also let home users run open community access wireless networks off a single purchased account. It is what NATs disable, however, that makes them nefarious. The paper considers how NATs work and the problems created by them.