Patent ID: 8201236

Claim:
A method comprising: preventing, by a firewall including an integrated intelligent network protocol gateway, interposed between an internal network and an external network, unauthorized network-layer 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; protecting, by the firewall, the plurality of internal hosts against application-layer threats from the external network and supporting Voice over IP (VoIP) services without compromising internal network security by actively processing signaling protocols associated with VoIP sessions, including distinguishing among VoIP packets and non-VoIP packets, 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; facilitating concurrent management by the firewall of a plurality of incoming VoIP calls by providing a plurality of VoIP ports on an external VoIP interface of the firewall, and advertising, by the firewall, a plurality of IP address/VoIP port pairs, wherein each IP address/VoIP port pair of the plurality of IP address/VoIP port pairs corresponds to one internal host of the plurality of internal hosts; receiving, by the external VoIP interface, a plurality of incoming VoIP packets each of which contains therein a user alias and a port indication regarding one of the plurality of VoIP ports; and causing each received incoming VoIP packet of the plurality of received incoming VoIP packets to be directed to an appropriate internal host of the plurality of internal hosts by port forwarding, by the firewall, the received incoming VoIP packet based on the port indication contained therein to a server or gatekeeper within the internal network that maintains a mapping of user aliases to private addresses of the plurality of internal hosts.