User device for communicating with an external device A user device for communicating with an external device via a virtual private network is suggested. The user device comprises a processing unit for generating a data packet to be transmitted to the external device, wherein a header of the data packet includes an authentication information of the user device for authenticating the user device, and a communication unit for communicating with the external device by transmitting the data packet to the external device via the virtual private network. Further, an external device for communicating with the user device and a method for a communication between a user device and an external device are suggested. The user device uses as an authentication for the virtual private network the header of the data packet. Thus, no additional authentication at the application layer is required.