Somebody tried to get access to my TYPO3 backend. I already have the IP adress of the attacker and want to block it from the backend.

I already tried to block ip with .htaccess but this doensn't work. I think the rules are overwritten by something else in the .htaccess file which I couldn't figure out yet.

Captcha is at the moment not a suitable solution.

Are there any good extensions for blocking IP adresses or is there another way to avoid these brute-force attacks?