Block all proxy servers

[webroy]

Hi ,

I have a customer behind my pfsense firewall. He has a lot of spammers on his website and want to block all traffic from proxy servers.. Is there a way or setting to do this? Are there llists to import all open proxy servers? is there a best way to block this traffic?

[webroy]

In Pfblocker i saw that you can add proxy lists

like :
http://iblocklist.charlieprice.org/f/eodsbdqxcbuomaagmvua/bt_spyware.gz

does some know  afrequently updated list for proxy servers?