Blocking based on a specific IP with htaccess
RewriteEngine On
RewriteBase /
RewriteCond %{REMOTE_ADDR} ^xx\.xx\.xx\.xx$ [OR]
RewriteCond %{REMOTE_ADDR} ^xx\.xx\.xx\.xx$
RewriteRule .* http://en.wikipedia.org/wiki/404_error [R,L]
RewriteEngine On
RewriteBase /
RewriteCond %{REMOTE_ADDR} ^xx\.xx\.xx\.xx$ [OR]
RewriteCond %{REMOTE_ADDR} ^xx\.xx\.xx\.xx$
RewriteRule .* http://en.wikipedia.org/wiki/404_error [R,L]