Search Indexing Problem

[Barley]

I have several folders with content that I do not want the search engines to crawl through and index for security reasons. None of these pages are linked from the main site, however I would like them to remain public for certain people who have links to these folders.

I know there is a way to tell the search engines not to crawl through certain folders by placing some kind of file in these folders but I have forgotten over the years. Any help would be much appreciated.

[ryanbutler]

Robots.txt:

http://www.robotstxt.org/orig.html