프록시가 사용 중일 때 실제 방문자 IP 주소를 얻는 방법은 무엇입니까?

<code class="php"><?php echo $_SERVER['REMOTE_ADDR']; ?></code>

<code class="php">function getUserIP()
{
    // Handle CloudFlare connections
    if (isset($_SERVER["HTTP_CF_CONNECTING_IP"])) {
          $_SERVER['REMOTE_ADDR'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
          $_SERVER['HTTP_CLIENT_IP'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
    }
    $client  = @$_SERVER['HTTP_CLIENT_IP'];
    $forward = @$_SERVER['HTTP_X_FORWARDED_FOR'];
    $remote  = $_SERVER['REMOTE_ADDR'];

    if(filter_var($client, FILTER_VALIDATE_IP))
    {
        $ip = $client;
    }
    elseif(filter_var($forward, FILTER_VALIDATE_IP))
    {
        $ip = $forward;
    }
    else
    {
        $ip = $remote;
    }

    return $ip;
}
$user_ip = getUserIP();</code>