A simple test by the AP has found that Comcast appears to interfere with the BitTorrent traffic in ways which pose ethics questions and also probably cost the company a lot of money. Specifically, instead of throttling BitTorrent traffic, the company appears to create spoof peers which interfere with the normal peer-to-peer transfers and significantly slow down or even kill some downloads. Furthermore, their test has shown that Comcast appears to "impersonate" existing peers to divert packets.

This is the most serious and concerning example yet of data discrimination by a U.S. Internet service provider because, according to AP, it involves company computers masquerading as those of its users. This technology requires costly resources, and it would probably have made more sense to invest the money in upgrading the network capacity.

Tests have shown that Comcast's dubious spoofing technology appears to activate itself after a file has been downloaded. Then its servers send messages to BitTorrent clients that terminate the connection, posing as real computers at the other end of the peer-to-peer connection. In their tests, the people working at AP chose to download a copy of the King James Bible through BitTorrent and found out that in two out of its three tests, the downloads were blocked altogether, while in the remaining test, the download started after a 10-minute delay.

"We have a responsibility to manage our network to ensure all our customers have the best broadband experience possible," spokesman Charlie Douglas said. "This means we use the latest technologies to manage our network to provide a quality experience for all Comcast subscribers."

This is especially worrying because it does not only affect Comcast subscribers (Comcast is the second-largest ISP in the country). The masquerading technology may disrupt BitTorrent transfers worldwide, and with them all the services that rely on it.

There is an ongoing debate about whether there should be regulation to impose ISP to treat all Internet traffic equally. Google and Amazon are fighting for such regulations, while Comcast, AT&T Inc. and others want to be able to "prioritize" certain types of traffic or traffic from a certain location. This means essentially that they're trying to make more money through a variety of mechanisms, for example charging certain fees from content providers to guarantee faster downloads from their servers.

"We don't believe that any Internet provider should be able to discriminate, block or impair their consumers' ability to send or receive legal content over the Internet," said Jen Howard, a spokeswoman for Free Press, which is a Washington-based public interest group that advocates Net Neutrality.

Comcast is suspected to be using technology similar to that provided by a Canadian company called Sandvine Inc. Sandvine claims its equipment saves bandwidth for ISPs by managing and redirecting file-sharing traffic.