PHP獲取用戶的真實IP地址

<?php

function getRealIpAddr() 
{ 
    if (!empty($_SERVER['HTTP_CLIENT_IP'])) 
    { 
        $ip=$_SERVER['HTTP_CLIENT_IP']; 
    } 
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) 
//to check ip is pass from proxy 
    { 
        $ip=$_SERVER['HTTP_X_FORWARDED_FOR']; 
    } 
    else 
    { 
        $ip=$_SERVER['REMOTE_ADDR']; 
    } 
    return $ip; 
} 

echo getRealIpAddr();

?>