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$ua->agent('Casper Bot Search'); ........ etc.
Ok, blocking "bot search" may be a little drastic... Does anyone know if any genuine bot has that phrase in its UA?
source: Google Webmaster Blog..In order to fetch from the "official" Googlebot IP range, the bot has to respect robots.txt and our internal hostload conventions so that Google doesn't crawl you too hard.
One may consider to block POST queries with a user agent as mentioned above (not: query strings)
"POST /I[DEX]887 HTTP/1.1" "MaMa CaSpEr"
"POST /contact.php HTTP/1.1" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6"