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Poison Null Protection
http://www.hackits.de/forum/thread.php?threadid=2052&sid=c0f877cb07d1426fed17d45f341ef29f
The author used a switch case statement that uses pages that are already there as cases and if the user tries to input a page that is not there already, then it goes to the index.php as a default.
a switch is deffinatly the way to go about it.
it's a long winded way of doing things, but by far the most secure.
example:
switch($_GET['page']){
case 'home':
include "home.php";
break;
case 'contact':
include "contact.php";
break;
default:
include "home.php";
}```