Authentication by MAC address
You will have to override the access callback used for your view pages using an hook_menu_alter implementation (from a custom module) to use a custom one that will do the MAC address check.

Assuming the MAC address is provided as an HTTP header, this would look like.

/**
 * Implements hook_menu_alter().
 */
function MODULE_menu_alter($items) {
  if (!isset($items['protected/view/path']['access arguments'])) {
    $items['protected/view/path']['access arguments'] = array($items['protected/view/path']['access callback']);
  }
  else {
    array_push($items['protected/view/path']['access arguments'], $items['protected/view/path']['access callback']);
  }
  $items['protected/view/path']['access callback'] = 'MODULE_menu_access';
}


/**
 * Return whether or not the request contains an authorized MAC address header. 
 */
function MODULE_menu_access() {
  $mac_address = $_SERVER['HTTP_MAC_ADDRESS'];

  // Validate the MAC address.
  if (!MODULE_mac_is_authorized($mac_address)) {
    return false;
  }

  // Return the result of the original access callback
  $args = func_get_args();
  $access_callback = array_pop($args);
  return call_user_func_array($access_callback, $args);
}