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Blocking bad bots and site rippers (aka offline browsers)

Note: This portion of tutorial written by JavaScript Kit

The definition of a "bad bot" varies depending on who you ask, but most would agree they are the spiders that do a lot more harm than good on your site (ie: an email harvester). A site ripper on the other hand are offline browsing programs that a surfer may unleash on your site to crawl and download every one of its pages for offline viewing. In both cases, both your site's bandwidth and resource usage are jacked up as a result, sometimes to the point of crashing your server. Bad bots typically ignore the wishes of your robots.txt file, so you'll want to ban them using means such as .htaccess. The trick is to identify a bad bot.

Below is a useful code block you can insert into.htaccess file for blocking a lot of the known bad bots and site rippers currently out there. It is derived from my reading of the excellent discussion "A close to perfect .htaccess file", specifically, "A close to perfect .htaccess file II." Simply add the below code to your .htaccess file:

RewriteEngine On 
RewriteCond %{HTTP_USER_AGENT} ^BlackWidow [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Bot\ mailto:craftbot@yahoo.com [OR] 
RewriteCond %{HTTP_USER_AGENT} ^ChinaClaw [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Custo [OR] 
RewriteCond %{HTTP_USER_AGENT} ^DISCo [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Download\ Demon [OR] 
RewriteCond %{HTTP_USER_AGENT} ^eCatch [OR] 
RewriteCond %{HTTP_USER_AGENT} ^EirGrabber [OR] 
RewriteCond %{HTTP_USER_AGENT} ^EmailSiphon [OR] 
RewriteCond %{HTTP_USER_AGENT} ^EmailWolf [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Express\ WebPictures [OR] 
RewriteCond %{HTTP_USER_AGENT} ^ExtractorPro [OR] 
RewriteCond %{HTTP_USER_AGENT} ^EyeNetIE [OR] 
RewriteCond %{HTTP_USER_AGENT} ^FlashGet [OR] 
RewriteCond %{HTTP_USER_AGENT} ^GetRight [OR] 
RewriteCond %{HTTP_USER_AGENT} ^GetWeb! [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Go!Zilla [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Go-Ahead-Got-It [OR] 
RewriteCond %{HTTP_USER_AGENT} ^GrabNet [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Grafula [OR] 
RewriteCond %{HTTP_USER_AGENT} ^HMView [OR] 
RewriteCond %{HTTP_USER_AGENT} HTTrack [NC,OR] 
RewriteCond %{HTTP_USER_AGENT} ^Image\ Stripper [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Image\ Sucker [OR] 
RewriteCond %{HTTP_USER_AGENT} Indy\ Library [NC,OR] 
RewriteCond %{HTTP_USER_AGENT} ^InterGET [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Internet\ Ninja [OR] 
RewriteCond %{HTTP_USER_AGENT} ^JetCar [OR] 
RewriteCond %{HTTP_USER_AGENT} ^JOC\ Web\ Spider [OR] 
RewriteCond %{HTTP_USER_AGENT} ^larbin [OR] 
RewriteCond %{HTTP_USER_AGENT} ^LeechFTP [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Mass\ Downloader [OR] 
RewriteCond %{HTTP_USER_AGENT} ^MIDown\ tool [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Mister\ PiX [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Navroad [OR] 
RewriteCond %{HTTP_USER_AGENT} ^NearSite [OR] 
RewriteCond %{HTTP_USER_AGENT} ^NetAnts [OR] 
RewriteCond %{HTTP_USER_AGENT} ^NetSpider [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Net\ Vampire [OR] 
RewriteCond %{HTTP_USER_AGENT} ^NetZIP [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Octopus [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Offline\ Explorer [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Offline\ Navigator [OR] 
RewriteCond %{HTTP_USER_AGENT} ^PageGrabber [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Papa\ Foto [OR] 
RewriteCond %{HTTP_USER_AGENT} ^pavuk [OR] 
RewriteCond %{HTTP_USER_AGENT} ^pcBrowser [OR] 
RewriteCond %{HTTP_USER_AGENT} ^RealDownload [OR] 
RewriteCond %{HTTP_USER_AGENT} ^ReGet [OR] 
RewriteCond %{HTTP_USER_AGENT} ^SiteSnagger [OR] 
RewriteCond %{HTTP_USER_AGENT} ^SmartDownload [OR] 
RewriteCond %{HTTP_USER_AGENT} ^SuperBot [OR] 
RewriteCond %{HTTP_USER_AGENT} ^SuperHTTP [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Surfbot [OR] 
RewriteCond %{HTTP_USER_AGENT} ^tAkeOut [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Teleport\ Pro [OR] 
RewriteCond %{HTTP_USER_AGENT} ^VoidEYE [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Web\ Image\ Collector [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Web\ Sucker [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebAuto [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebCopier [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebFetch [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebGo\ IS [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebLeacher [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebReaper [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebSauger [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Website\ eXtractor [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Website\ Quester [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebStripper [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebWhacker [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WebZIP [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Wget [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Widow [OR] 
RewriteCond %{HTTP_USER_AGENT} ^WWWOFFLE [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Xaldon\ WebSpider [OR] 
RewriteCond %{HTTP_USER_AGENT} ^Zeus 
RewriteRule ^.* - [F,L]

Bots that are listed above will all receive a 403 Forbidden error when trying to view your site. The amount of bandwidth savings and decrease in server resource usage as a result may be significant in many cases.