ISP为何能检测到你非法下载东西？见内

http://ask-leo.com/how_can_my_isp_tell_that_im_downloading_copyrighted_files.html

这就因为我的ISP帐号里唯一的一次非法下载的东西是于6/17/2010下载的”Up In The Air”, 可能是通过运行了P2P共享软件而遭到ISP警告：严管我的家网, 而不是他们声称的于5/9/2010下载的"The Hurt Locker".如果再遭一次ISP警告,根据协议他们有权中断我的网络服务。

How can my ISP tell that I'm downloading copyrighted files?

ISP can't examine the data, but they can still see where the data is coming and going, and what kind of data it is.

So even encrypted your ISP could still say "hey, you're running peer-to-peer file sharing software, and we don't allow that: knock it off".

Yes, there are attempts to further obfuscate peer-to-peer file sharing traffic, but you get the idea - for the most part even if the ISP can't see what you're sharing, they can see that you're sharing.

And for many, that's enough.