Hello, I want to know the difference between these rules and which is most effective to block libwww-perl with the file .htaccess SetEnvIfNoCase User-Agent "libwww-perl" bad_bot Order Deny,Allow Deny from env=bad_bot Code (markup): or RewriteCond %{HTTP_USER_AGENT} libwww-perl.* RewriteRule .* – [F,L] Code (markup):