A gateway for connecting a public network to an internal network is provided. The gateway comprises a control unit for controlling transmission of incoming and/or outgoing data between a remote device in the public network and an internal device in the internal network; a public port connected to the public network; an internal port connected to the internal network; and a storage unit storing a list of public key identifiers and respectively associated internal network addresses of internal devices; wherein the control unit is adapted for identifying a destination of the incoming data, which are addressed to a public network address of the gateway, by determining an internal network address of the internal device based on public key information included in the incoming data and the list of public key identifiers and associated internal network addresses.