HTTP: Proxy Check
Ivan Markovic (contact me)
This class can be used to check whether the user is accessing the site via a proxy server.
It retrieves all known request headers that may be used to determine the proxy server the user may be using to access the site.
The class can also check several well known ports of a given IP to determine the port that may be used to connect to a proxy server.
Click here for detailed information about this class on phpclasses.org
Php Handleiding