Generate a dictionary mapping MAC address to Ethernet interfaces.

    Returns:
      dict, string MAC addresses mapped to the string network interface name.

def _CreateInterfaceMapNetifaces(self):
    """Generate a dictionary mapping MAC address to Ethernet interfaces.

    Returns:
      dict, string MAC addresses mapped to the string network interface name.
    """

    interfaces = {}
    for interface in netifaces.interfaces():
      af_link = netifaces.ifaddresses(interface).get(netifaces.AF_LINK, [])
      mac_address = next(iter(af_link), {}).get('addr', '')
      # In some systems this field can come with an empty string or with the
      # name of the interface when there is no MAC address associated with it.
      # Check the regex to be sure.
      if MAC_REGEX.match(mac_address):
        interfaces[mac_address] = interface
      else:
        message = 'Unable to determine MAC address for %s.'
        self.logger.warning(message, interface)
    return interfaces