Code:
# block proxy servers from site access
# http://site name here
RewriteEngine on
RewriteCond %{HTTP:VIA} !^$ [OR]
RewriteCond %{HTTP:FORWARDED} !^$ [OR]
RewriteCond %{HTTP:USERAGENT_VIA} !^$ [OR]
RewriteCond %{HTTP:X_FORWARDED_FOR} !^$ [OR]
RewriteCond %{HTTP:PROXY_CONNECTION} !^$ [OR]
RewriteCond %{HTTP:XPROXY_CONNECTION} !^$ [OR]
RewriteCond %{HTTP:HTTP_PC_REMOTE_ADDR} !^$ [OR]
RewriteCond %{HTTP:HTTP_CLIENT_IP} !^$
RewriteRule ^(.*)$ - [F]
copy and paste this into your site’s root htaccess file it will not stop them all but will catch the majority.