if (empty($this->input->server('PHP_AUTH_USER')))
   {
       header('HTTP/1.0 401 Unauthorized');
       header('HTTP/1.1 401 Unauthorized');
       header('WWW-Authenticate: Basic realm="My Realm"');
       echo 'You must login to use this service'; // User sees this if hit cancel
       die();
    }

    $username = $this->input->server('PHP_AUTH_USER');
    $password = $this->input->server('PHP_AUTH_PW');

// Check username and password