Maintaining address translations for data communications

(57) Summary book invention offers the method for providing network security services, such as service provided by the IPSEC protocol, through network address translation (NAT). This method opts for the conversion produced in a packet, and is based on compensating this conversion. Since only TCP and an UDP protocol process NAT, an IPSEC AH/ESP packet is encapsulated for transport and turns into an UDP packet. Special operation is performed in order to enable communication reliable in this environment.