Detecting proxy using PHP?

[isaac]

I'm just wondering if it is possible to detect if an user is behind a proxy using PHP or CGI? And/or identify the user's real IP?

Thanks!

[vayasin]

i don't think so. you could maby see if the request ip is a proxy but getting the client ip would be inpossible. that is why proxy's are used for anonymous surfing.

[Smoky]

the best iv used to get the IP address of a client maybe not through a proxy but through a cache server is....

if (getenv("HTTP_CLIENT_IP"))
{
$ip = getenv("HTTP_CLIENT_IP");
}
else if(getenv("HTTP_X_FORWARDED_FOR"))
{
$ip = getenv("HTTP_X_FORWARDED_FOR");
}
else if(getenv("REMOTE_ADDR"))
{
$ip = getenv("REMOTE_ADDR");
}
else
{
$ip = $_SERVER['REMOTE_ADDR'];
}

I believe i might have went through the proxy too... Try it