Control method for authentication of a connection device (4,5,7,8,9) connected to a network, in particular a network mounted on a boat, comprising the steps of: performing an authentication-free determination to determine whether or not the connection device (4,5,7,8,9) corresponds to an authentication-free device, performing an authenticating action (S4 to S6) with the connection device (4,5,7,8,9) if the connection device (4,5,7,8,9) does not correspond to an authentication-free device (No at S3), and exempting the connection device (4,5,7,8,9) from the authenticating action (S4 to S6) if the connection device (4,5,7,8,9) corresponds to an authentication-free device (Yes at S3), wherein the connection device (4,5,7,8,9) is instructed to transmit an address requesting message before the authentication-free determination is performed, wherein the connection device (4,5,7,8,9) connected to the network is a gage and/or a gateway and/or a remote control and/or an immobilizer and/or a multi-function sensor, and the address requesting message comprises an identification field comprising priority and/or communication identification and/or destination address and/or source address, and the address requesting message comprises a data field comprising manufacturer code and/or device classes and/or device functions, wherein in the authentication-free determination, it is determined whether or not the connection device (4,5,7,8,9) corresponds to an authentication-free device based on a manufacturer code in the address requesting message while defining the authentication-free device to be a connection device manufactured by a specific manufacturer representing the manufacturer of the connection device (4,5,7,8,9) or corresponds to an authentication-free device based on based on a device class contained in the address requesting message while defining the authentication-free device to be a connection device belonging to a specific device class. performing an authentication-free determination to determine whether or not the connection device (4,5,7,8,9) corresponds to an authentication-free device, performing an authenticating action (S4 to S6) with the connection device (4,5,7,8,9) if the connection device (4,5,7,8,9) does not correspond to an authentication-free device (No at S3), and exempting the connection device (4,5,7,8,9) from the authenticating action (S4 to S6) if the connection device (4,5,7,8,9) corresponds to an authentication-free device (Yes at S3), wherein the connection device (4,5,7,8,9) is instructed to transmit an address requesting message before the authentication-free determination is performed, wherein the connection device (4,5,7,8,9) connected to the network is a gage and/or a gateway and/or a remote control and/or an immobilizer and/or a multi-function sensor, and the address requesting message comprises an identification field comprising priority and/or communication identification and/or destination address and/or source address, and the address requesting message comprises a data field comprising manufacturer code and/or device classes and/or device functions, wherein in the authentication-free determination, it is determined whether or not the connection device (4,5,7,8,9) corresponds to an authentication-free device based on a manufacturer code in the address requesting message while defining the authentication-free device to be a connection device manufactured by a specific manufacturer representing the manufacturer of the connection device (4,5,7,8,9) or corresponds to an authentication-free device based on based on a device class contained in the address requesting message while defining the authentication-free device to be a connection device belonging to a specific device class.