Question

Okay, take this user agent for example:

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.6) Gecko/20100625

Curious as to what all of it means. I can figure out a few things, obviously, such as Mozilla == Firefox, and Windows NT 5.1 == Windows XP. But what is the rv:1.9.2.6, and What is Gecko? and U?

And also, I’m working on setting up a script that puts various pieces of it into separate variables, such as the Mozilla, and the Windows NT 5.1, but how would I go about using RegEx to extract that, if most (if not all) of the other sections in the User Agent would by dynamic based on each user?

Answer 1

Let’s see: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.6) Gecko/20100625

• Mozilla/5.0 – meaningless artifact from the era of the dinosaurs; nowadays, almost every browser identifies as Mozilla (even IE, Chrome, and Opera).
• Windows – OS
• U – strong security available (N would stand for “no security” and I for “weak security”)
• Windows NT 5.1 – OS version. 5.1 is Windows XP, 6.0 is Vista, 6.1 is Windows “It’s Not Vista SP” 7
• en-US – browser locale – in this case, English – American
• rv:1.9.2.6 – version of the Gecko renderer
• Gecko/20100625 – renderer build date: 2010-06-25

Anyway, this header is essentially meaningless, as several browsers provide ways of spoofing it (at least Firefox and Opera).