Why be forbbiden?Question about apache & php

apachluxun

:help I am on a Fedora3. Everything is just update to newest version.But alway get the problem:

You don't have permission to access /index.php on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

I have write a page named index2.php which include "phpinfo()" .It's come out exactly correct.
What's the problem ...