A device for handling messages between a vehicle Electronic Control Unit, ECU, in an ECU enclosure and a vehicle communication bus under control of a data unit, each of the messages is composed of multiple parts, the device comprising: a first physical port for connecting to the ECU; a first transceiver coupled to the first physical port for transmitting messages to, and for receiving messages from, the ECU; a second physical port for connecting to the communication bus; and a second transceiver coupled to the second physical port for transmitting messages to, and for receiving messages from, the communication bus; wherein: the device is handling the messages under control of a data unit and all the messages received from the ECU and from the communication bus are associated with a timing information, and the device further comprising: a third physical port for connecting to the data unit; a third transceiver coupled to the third physical port for receiving from the data unit a rule associated with a part of the message; a software and a processor for executing the software, the processor is coupled for controlling the first, second, and third transceivers; and a single enclosure for housing the first, second, and third physical ports, the first, second, and third transceivers, and the processor, wherein the single enclosure is distinct from, and external to, the ECU enclosure, wherein the rule includes one or more timing values, wherein messages to the communication bus via the second physical port received from the ECU via the first physical port are passed or blocked in response to comparing of the specific message timing information to the one or more rule timing values, and wherein messages to the ECU via the first physical port received from the communication bus via the second physical port are passed or blocked in response to comparing of the specific message timing information to the one or more rule timing values. a first physical port for connecting to the ECU; a first transceiver coupled to the first physical port for transmitting messages to, and for receiving messages from, the ECU; a second physical port for connecting to the communication bus; and a second transceiver coupled to the second physical port for transmitting messages to, and for receiving messages from, the communication bus; wherein: the device is handling the messages under control of a data unit and all the messages received from the ECU and from the communication bus are associated with a timing information, and the device further comprising: a third physical port for connecting to the data unit; a third transceiver coupled to the third physical port for receiving from the data unit a rule associated with a part of the message; a software and a processor for executing the software, the processor is coupled for controlling the first, second, and third transceivers; and a single enclosure for housing the first, second, and third physical ports, the first, second, and third transceivers, and the processor, wherein the single enclosure is distinct from, and external to, the ECU enclosure, a third physical port for connecting to the data unit; a third transceiver coupled to the third physical port for receiving from the data unit a rule associated with a part of the message; a software and a processor for executing the software, the processor is coupled for controlling the first, second, and third transceivers; and a single enclosure for housing the first, second, and third physical ports, the first, second, and third transceivers, and the processor, wherein the single enclosure is distinct from, and external to, the ECU enclosure, wherein the rule includes one or more timing values, wherein messages to the communication bus via the second physical port received from the ECU via the first physical port are passed or blocked in response to comparing of the specific message timing information to the one or more rule timing values, and wherein messages to the ECU via the first physical port received from the communication bus via the second physical port are passed or blocked in response to comparing of the specific message timing information to the one or more rule timing values.