A communication system for securely communicating data packets between a first device and a second device, the communication system comprising: - a first network being based on a first transport protocol, - a first device (124, 136) being configured to communicate via the first network with other devices, the first device (124, 136) being configured to apply a first transport security protocol on top of the first transport protocol, - a second network being based on a second transport protocol, - a second device being configured to communicate via the second network with other devices, the second device being configured to apply a second transport security protocol on top of the second transport protocol, - an intermediate device configured to communicate via the first network with the first device (124, 136) and configured to communicate via the second network with the second device, and being configured to modify data packets received via the first network which are generated in accordance to the first transport security protocol towards data packets for communication via the second network in accordance with the second transport security protocol, and vice versa, wherein - the first transport protocol or the second transport protocol is a datagram based network protocol and the other one of the first transport protocol or the second transport protocol is a reliable connection oriented transport protocol, characterized in that - the first device (124, 136) is configured to reconstruct a header of a first data packet received from the intermediate device such that the header corresponds to a header of a second packet that was communicated by the second device to the intermediate device and was modified by the intermediate device to the first data packet, and - the first device is configured to verify a security verification field of a received data packet on basis of the reconstructed header of the first data packet, the verification field being generated by the second device in accordance with the second transport security protocol. - a first network being based on a first transport protocol, - a first device (124, 136) being configured to communicate via the first network with other devices, the first device (124, 136) being configured to apply a first transport security protocol on top of the first transport protocol, - a second network being based on a second transport protocol, - a second device being configured to communicate via the second network with other devices, the second device being configured to apply a second transport security protocol on top of the second transport protocol, - an intermediate device configured to communicate via the first network with the first device (124, 136) and configured to communicate via the second network with the second device, and being configured to modify data packets received via the first network which are generated in accordance to the first transport security protocol towards data packets for communication via the second network in accordance with the second transport security protocol, and vice versa, - the first transport protocol or the second transport protocol is a datagram based network protocol and the other one of the first transport protocol or the second transport protocol is a reliable connection oriented transport protocol, - the first device (124, 136) is configured to reconstruct a header of a first data packet received from the intermediate device such that the header corresponds to a header of a second packet that was communicated by the second device to the intermediate device and was modified by the intermediate device to the first data packet, and - the first device is configured to verify a security verification field of a received data packet on basis of the reconstructed header of the first data packet, the verification field being generated by the second device in accordance with the second transport security protocol.