A first bus interface is coupled to communicate with a first controller area network (CAN) bus. A second bus interface is coupled to communicate with a node device, the node device configured to communicate with a second CAN bus. A logic circuit is coupled between the first and second bus interfaces and is operable to monitor communications by the node device via the second bus interface. If the logic circuit determines that the node device is transmitting a message that is not allowed for the node device, it prevents the message from being transmitted onto the first CAN bus in response thereto.