Patent ID: 7716725

Claim:
A method comprising: a firewall, interposed between an internal network and an external network, providing network-layer protection against unauthorized access by hosts associated with the external network to a plurality of internal hosts associated with the internal network by performing network address translation (NAT) processing of Internet Protocol (IP) addresses associated with the plurality of internal hosts; the firewall providing application-layer protection from the external network on behalf of the plurality of internal hosts and supporting VoIP services without compromising internal network security by actively processing signaling protocols associated with Voice over IP (VoIP) sessions, including distinguishing among VoIP packets and non-VoIP packets, understanding and parsing the VoIP packets at the application layer, and performing content-aware NAT by changing data in headers of the VoIP packets and also changing data contents in the VoIP packets corresponding to data changed in the headers to enable bi-directional VoIP communications among one or more of the plurality of internal hosts and one or more of the hosts associated with the external network; providing a plurality of VoIP ports to an external VoIP interface of the firewall; receiving by the external VoIP interface incoming VoIP packets each having associated therewith a user alias and an indication regarding one of the plurality of VoIP ports; causing each of said received multiple incoming VoIP packets to be directed to an appropriate internal host of the plurality of internal hosts by performing by the firewall port address forwarding based on the port indication to an H.323 gatekeeper within the internal network that maintains a mapping of user aliases to private addresses of the plurality of internal hosts; wherein the user alias comprises an email address of a user associated with one of the plurality of internal hosts; and wherein the firewall comprises an intelligent network protocol gateway device.