PHP에서 클라이언트의 IP 주소를 안정적으로 얻는 방법은 무엇입니까?

// Function to get client IP address
function get_client_ip() {
    $ipaddress = '';
    if (getenv('HTTP_CLIENT_IP'))
        $ipaddress = getenv('HTTP_CLIENT_IP');
    else if (getenv('HTTP_X_FORWARDED_FOR'))
        $ipaddress = getenv('HTTP_X_FORWARDED_FOR');
    //... (Other conditions omitted for brevity)
    else
        $ipaddress = 'UNKNOWN';
    return $ipaddress;
}

// Function to get client IP address
function get_client_ip() {
    $ipaddress = '';
    if (isset($_SERVER['HTTP_CLIENT_IP']))
        $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
    else if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
    //... (Other conditions omitted for brevity)
    else
        $ipaddress = 'UNKNOWN';
    return $ipaddress;
}