http://w27irt6ldaydjoacyovepuzlethuoypazhhbot6tljuywy52emetn7qd.onion/mirrors/Internet%20Census%202012/Working%20with%20the%20Internet%20Census%202012.html
The probed IP address
returns a state of 1 (open), 2 (open filtered), 3 (reset), 4
(closed/reset), or 5 (timeout). Although 175 billion probes were saved,
only a small minority of the data has a return state of 1. For IP
addresses returning a state of 2-5, the file lists only the number and
no further explanation.