I'm looking for a method, or a way to detect clients using any type of proxy server viewing my web site. I'm using PHP/Apache... what's the best way to do this? Any proxy server would need to be detected, not specifically one or the other.
I am more interested in the anonymous proxies... as the normal ones are easily detected by looking for
You can't detect that unless they pass on special headers which explictly mention it like X-Forwarded-For or something.
As far as I know you have to use a blacklist. Users who use putty portforwarding, VPN or other more sophisticated methods are undetactable as they behave exactly like normal users.