Some users of the anonymous web browser Tor have reported that Comcast has threatened to cut off their internet service unless they stop using the legal software.
Comcast completely denies their claims. In a blog post, the company said "We have no policy against Tor, or any other browser or software. Customers are free to use their Xfinity Internet service to visit any website, use any app, and so forth."
http://www.businessinsider.com/comcast-threatens-to-cut-off-tor-users-2014-9