How do methods $_SERVER['HTTP_REFERER'] and RewriteCond %{HTTP_REFERER} !^$ differ?

sherry · May 14, 2007

1) How do methods "$_SERVER['HTTP_REFERER']" and "RewriteCond %{HTTP_REFERER} !^$" differ?

Specifically, does this description for $_SERVER['HTTP_REFERER'] also apply to the .htaccess RewriteCond %{HTTP_REFERER} !^$ method:

re: $_SERVER['HTTP_REFERER'] - The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.

2) Also, what is the result of this particular statement:

RewriteCond %{HTTP_REFERER} !^$

I can figure out the other statements that go along with this one.

I'd like to prevent direct access to a file.  I want its access to come from a link on my website.


Thanks.