Data transmission system with a mechanism enabling any application to run transparently over a network address translation device

A data transmission system operating with the Internet protocol (IP) comprising:

• a workstation
• a peer device;
• a private transmission network;
• a network address translation device (NAT);
• a public transmission network interconnected by the NAT to the private transmission network, wherein the workstation connected to the private transmission network is operative for communicating the peer device, the peer device connected to the public transmission network, the local IP address of each data packet from the workstation is translated into a NAT address used to provide the routing through the public transmission network;
• and
• a registration server connected to the public transmission network for registering a local IP addresses corresponding to a NAT address and for providing the correspondence between the NAT address and the local IP address to the peer device in order to replace the NAT address with the local IP address in an IP header of each data packet received by the peer device,.

A method of enabling an application to run transparently in a data transmission system operating with the Internet protocol (IP) comprising a public transmission network, a public network, a workstation, interconnected by a network address translation device (NAT) to the private transmission network, wherein the workstation connected to the private transmission network is operative for communicating the peer device, the peer device connected to the public transmission network, the local IP address of each data packet from the workstation is translated into a NAT address used to provide the routing through the public transmission network, the method comprising the steps of:

• registering (REG) in a registration server the local IP address corresponding to the NAT address,
• requesting from the peer device to the registration server, the local IP address corresponding to an unknown NAT address of a received data packet,
• receiving at the peer device, the local IP address from the registration server;
• and
• replacing in the peer device, the NAT address of a received data packet with a local IP address.