I suppose each of us browsing through the search results came across forums that were available only to authorized members. There was a question - how could Google / Yahoo / etc ... be able to index them? A typical answer to this question was: "There is no mystery, he first indexed, and then they already limited viewing." But today, digging into the depths of IPB, I found something else. Namely: The setting “Treat spider / bot as part of which group?”, Which by default stands as “Member”. We look below, and see "Spider Bot User-Agent", which clearly indicates the identification of bots by the User-Agent header. We are conducting an experiment. We go to the IPB, being not authorized, and get the status of guest. Is logical. Now (I use LiveHeaders for FF) we add the googlebot keyword to my User-Agent. And voila, we get member status! Note: Tested only for Invision Power Board.