I put this here because - "Who ever reads the chat forums"? Besides, I don't speak'a de Italiano to be able to add it there too. (Sorry MG)
Reference:
http://ahrefs.com/robot/
You are advised to add this to your robots.txt in the root of the Public-Folder and the robots.txt in root folders of anything else you may have on your server.
user-agent: AhrefsBot
disallow: /
My log is absolutely full of "already has more than 'max_user_connections' active connections"
And this ugly bot from:
6:14:02pm to 7:47:26pm - When I stopped it with a quick "Deny All - Everything" until I could work out what was happening, had made 2,992 queries on the database.
But at the same time through its actions, had cached 2,992 files for me. So I suppose I should be grateful for that and not complain about the DDos attack.