Originally Posted by towny

There are researchers out there who have been developing ways of 'sniffing' behind a router by sending packets of data into a network and then analysing those packets as they come back out. Apparently you can tell with a fair degree of accuracy how many machines are there and what kind of machines they are. Somehow I doubt NTL is so cutting edge that they are employing these techniques yet, however I have no doubt they would like to, as it would be fairly easy for them to spot if someone was, for example, using Xbox Live without having paid their extra £5.