Advanced .htaccess Tricks for Securing Sites
This is all new, experimental, and very very cool. It literally uses .htaccess techniques to create several virtual "locked gates" that require a specific key to unlock, in a specific order that cannot be bypassed. It uses whitelisting .htaccess tricks to specify exactly what is allowed, instead of trying to specify everything that isn't allowed. Also, by setting specific cookies/tokens after successfully passing through a gate, we can then require the exact cookie/token from the previous gate, which stops an attacker from skipping or bypassing gates.