小栗子:

        if (isset($_SERVER['PHP_AUTH_USER']) && isset($_SERVER['PHP_AUTH_PW'])) {
            $user = 'admin';
            $passwd = '123';
            if ($_SERVER['PHP_AUTH_USER'] == $user && $$_SERVER['PHP_AUTH_PW'] == $passwd) {
                echo 'login success';
            } else {
                echo 'login fail';
            }
        } else {
            Header("WWW-Authenticate: Basic realm=USER LOGIN");
            Header("HTTP/1.0 401 Unauthorized");            
        }