Http_referer

I am trying to use the http_referer function in the cgi variables to restrict access to parts of my boards unless a person has come from a link inside the boards. Is there a fooproof way to do this as it seems some borwsers do not require the referer to be sent as part of he header. Or is there another way to do it that works properly. Or is there a way to turn this on in the headers of the browser that is easy to understand and the simple user can follow.