Sorry, but I think you are in some weird kind of 'damage control' mode here.<p>First of all, one hit per second, or even 4 is ridiculously low and most other search engines crawl at a much higher rate.<p>Second, you really should learn how to use robots.txt and what nofollow is really for.<p>As for 80 legs, they should start caching stuff so one client crawling a page will have the effect that other clients of theirs will not be revisiting that same page for a while.<p>If a relatively low volume crawler is already a ddos attack in your book then I hope that you will never be subjected to a real one because it will be curtains for your site in a heartbeat.