Blocking Proxys via .htaccess file

ok umm here is what I need.

I need a proxy Spam Filteration Blocking thing on my site so if i try and access my site using proxy it will lead them to my 403.shtml file yes I could go deny from www.???.com it will take forever I need something better something that will block like 99% of proxys in one hit can you post me a script I have come across

# block proxy servers from site access
# http://perishablepress.com/press/2008/04/20/how-to-block-proxy-servers-via-htaccess/

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]

Yes I'v doesn't work I tried it on a couple of proxy's all got through succesfully. Reason why I want to do now yesterday had a spam attack blocked IP however I think his next return will be via proxies! I want to be one step ahead.

The HTTP headers that code is testing are optional and are only set by legitimate proxy servers. A legitimate proxy server is one that wants you to know it is a proxy, such as a proxy at a large company that is used by all the client computers within that company. The code would basically block visitors to your site who's Internet connection happened to be using a proxy server at their point of connection to the Internet.

The kind of proxy servers you want to block are called anonymous proxy servers (they don't want you to know they are proxy servers) and they DON"T set those HTTP headers. The only real way to block these kind of proxy servers would be to learn the IP address of each of them (each will either have one fixed IP address or a fixed block (subnet) of IP addresses) and deny connections from those IP addresses or blocks of IP addresses.