Msg#: 4571674 posted 9:47 pm on May 7, 2013 (gmt 0)
This is one of those under-the-radar robots. Logs tell me they've stopped by periodically since late June of 2012, but I never noticed until they ventured beyond the front page. (I am not a front-driven site-- in fact until recently I didn't even have a front page-- so I generally ignore requests for / alone, even without robots.txt.)
Disclaimer: I realize that the following is equivalent to "a man in his thirties, average height, average weight, brown hair, no distinguishing marks". But you never know.
Considering FF's recent behavior, this alone is enough to raise suspicion: the same version for over 10 months? At the time of their first visit, FF was just starting its update binge; the current version was 13.0 but 12.0 was no more than 2 months old.
WhoIs says they belong to RCN Corporation, which is apparently a regular human ISP. The main cause for suspicion is that they're based in Herndon, VA.
Hm. Maybe it's time to add Old Firefox to the Old MSIE group. (Redirect to a page that says "I'm sorry, but the server thinks you are a robot." No links; captcha for e-mail. Exceptions for one directory and a couple of IP ranges.)