Patent ID: 7206312

Claim:
A network address conversion system for enabling an access to a specific node of a private network, having a private IP address and an internal port value, comprising: a reservation unit which receives an access reservation demand from an external network node to access the specific node of the private network; an external port value allocation unit which allocates a first external port value to the specific node, which is different from the internal port value of the specific node of the private network, in response to receiving the access reservation demand from the external node, and transmitting the first external port value to the external network node; a mapping table which records a mapping relationship between the first external port value that is allocated and the internal port value of the specific node of the private network; and an address conversion unit which converts the first external port value into the private IP address of the specific node, when the external network node accesses the specific node by using the first external port value, wherein the first external port value that is allocated to the specific node in response to receiving the access reservation demand from the external node is a new port value and said new port value is allocated when the access reservation demand is received, wherein the address conversion unit receives a response packet from the external node that includes the new port value and converts the new port value to the internal port value such that the response packet is transmitted to the specific node with the internal port value.