My board is under attack

[TLCanna]

There has been some sort of web crawler or web bot that has been going through my board for the last week. It's logged in as a guest. It attempts to try every function on the board and it's IP always begines with 66.196.72.*

Here is how I have tried to get rid of it, but nothing has worked.

1.) I tried to do a partial ban thru control panel.

2.) I added some code to redirect it:

if (substr($REMOTE_ADDR, 0, 9) == "66.196.75"){
header("Location: http://www.google.com/");
exit;
}


Nothing will phase it. Help me please!