Abstract: Method for secure on-board communication between components (2, 4) of a vehicle by way of a communication bus (6) of the vehicle. The method includes (Si) sending a message from a component (2; 4) to the communication bus (6), (S2) storing information of the message sent in the component (2; 4), (S3) reading all the messages on the communication bus (6) by the component (2; 4), (S4) comparing information in the messages read with the information in the message sent by the component (2; 4), and (S5) initiating a countermeasure in reaction to a deviation based on the comparison of information in the read messages with the information in the sent message. Also disclosed is a control unit, a system and a vehicle which are designed to carry out such a method for secure on-board communication between components.