DEVICE AND METHOD FOR COMMUNICATING WITH ANOTHER COMMUNICATION DEVICE VIA NETWORK FORWARDING DEVICE

The communication device includes a first transmitting unit that transmits to a server a first message transmitted according to a first protocol; a receiving unit that receives a port number message including a translated port number from the server via the network forwarding device; a first protocol processing unit that generates a second message that is to be transmitted according to the first protocol; a second protocol processing unit that generates a third message in which the first protocol is concealed by appending, to the generated second message, a header according to a second protocol; a third protocol processing unit that generates a fourth message in which the first protocol is concealed by appending, to the generated third message, a header according to a third protocol; and a second transmitting unit that transmits the generated fourth message to the server via the network forwarding device.