Определение реального IP

function ip(){
if (isset($_SERVER['HTTP_X_REAL_IP'])) {
return $_SERVER['HTTP_X_REAL_IP'];
} else {
if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
return $_SERVER['HTTP_CLIENT_IP'];
} elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
return $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
return $_SERVER['REMOTE_ADDR'];
}
}
}