http://visiolist.com/community/threads/test-proxy-prevention.1026/ this has shown some good success with proxies.
Issues with other php or htaccess methods is that most proxies block/remove the stuff we need to check if its a proxy or not. And ofcouse, you would block every legitimate use behind a normal home proxy connection.
Is http referrer check also meant for the proxy stuff? if so, skip it. That header can be faked or even can be blank, so not really something to rely on.
Cant even say, "block vote when referrer is empty"
Can be blank, when
- entered the site URL in browser address bar itself. so just paste the proxy url in the browser manally and you bypass it
- visited the site by a browser-maintained bookmark.
- visited the site as first page in the window/tab.
- switched from a https URL to a http URL.
- switched from a https URL to a different https URL.
- has security software installed (antivirus/firewall/etc) which strips the referrer from all requests.
- is behind a proxy which strips the referrer from all requests.
- visited the site programmatically (like,curl) without setting the referrer header (searchbots!).
That being said, even a public blacklist would be really unsafe for that reason
So, with the warning being said, you still want something coded? There exist also php code which isnt even hard to implement, but again, blocks many valid people, like we experienced in the past and people simply removed that again, as such a thing is not worth it. Your choice