I think this function is also a good soloution to find users real IP address.
function getrealip()
{
if (isset($_SERVER)){
if(isset($_SERVER["HTTP_X_FORWARDED_FOR"])){
$ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
if(strpos($ip,",")){
$exp_ip = explode(",",$ip);
$ip = $exp_ip[0];
}
}else...