I recently found out that Comcast blocks Gnutella after trying to share a copy of the Bitcoin blockchain with the community using Gnutella. They completely block the Gnutella port, and when Gnutella operates on other ports they seem to mangle the network such that you can still download but you can't upload any files. Your Gnutella note also can't operate as an ultra peer because Comcast disconnects leaf connections. An ultra peer is a node that participates in network searches and routing, so that a few hundred leaves can connect to an ultra peer instead of being ultra peers, which makes the network more efficient.
They mess with sharing on torrents too but they don't block uploading completely.
Here is an article about it:
http://www.nbcnews.com/id/21376597/ns/technology_and_science-internet/t/comcast-blocks-some-internet-traffic/I'm not a supporter of net neutrality legislation that would put unneeded burdens on other ISPs that aren't doing things kinds of things, and the proper solution for me is to switch ISPs, but Comcast is doing is awful!
Bitcoin is a bandwidth heavy P2P application. Will Comcast block Bitcoin users' Bitcoin clients from sending out blockchains to other users as well?
