Get the real client ip in php

if (!empty($_SERVER["HTTP_CLIENT_IP"]))
{
 //Verif sur le net ? 
 $ip = $_SERVER["HTTP_CLIENT_IP"];
}
elseif (!empty($_SERVER["HTTP_X_FORWARDED_FOR"]))
{
 // Proxy ?
 $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
}
else
{
 $ip = $_SERVER["REMOTE_ADDR"];
}
echo $ip;