Patent ID: 7774475

Claim:
A method for operating a symmetric Network Address Translation (NAT) for setting up sessions between a user terminal and a server, comprising the steps of: determining an external internet protocol (IP) address and an external IP port representing said server as well as a public NAT-IP address if a new session is initiated by said user terminal or said server; selecting a public NAT-IP port for said new session; and setting up the new session between said user terminal and said server via said selected public NAT-IP port based on an entry in a first NAT-table representing sessions currently allowed to run via said NAT; generating a tuple comprising the public NAT-IP address, the selected public NAT-IP port, the external IP address and the external IP port as a session identifier which individually identifies the new session; and the setting up of the new session is based on an entry of said tuple in said first NAT-table; and wherein the public NAT-IP address, the selected public NAT-IP port, the external IP address and the external IP port of the tuple are destination components.