获取客户端真实ip地址

getrealip.php

<?php
function GetIP(){
        if (getenv("HTTP_CLIENT_IP") 
        && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
       $ip = getenv("HTTP_CLIENT_IP");
    else if (getenv("HTTP_X_FORWARDED_FOR") 
        && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
       $ip = getenv("HTTP_X_FORWARDED_FOR");
    else if (getenv("REMOTE_ADDR") 
        && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
       $ip = getenv("REMOTE_ADDR");
    else if (isset($_SERVER['REMOTE_ADDR']) 
        && $_SERVER['REMOTE_ADDR'] 
        && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
       $ip = $_SERVER['REMOTE_ADDR'];
    else
       $ip = "unknown";
    return($ip);
}
$ip = GetIP();
echo $ip;
exit;