Null-packet transmission from inside a firewall to open a communication window for an outside transmitter

摘要

A high-bandwidth direct communication path between two clients is used for voice or video calls over the Internet. An opening or a window in a firewall is made for the direct path by sending a null packet out from inside the firewall. The null packet can be a UDP packet directed to a UDP port of the other client. Initially, each client makes a TCP connection to port 80 of an external manager. Each client registers its UDP port number with the external manager. A call request from one client to the external manager results in a message from the external manager to the other client. The other client then creates the window in its firewall by transmitting the null UDP packet. Then the external manager is notified and tells the calling client to begin sending UDP packets directly to the other client through the firewall window.

主权项

1. A method for managing communication over a data communication network, the method comprising:
providing an external communication manager on the data communication network outside of a first firewall; first registering, at the external communication manager, first communication channel information about a first communication application by registering first IP address data associated with the first communication application and firewall window data for the first firewall, said first communication application being separated from the data communication network by the first firewall; second registering, at the external communication manager, second communication channel information about a second communication application by registering second IP address data associated with the second communication application, said second communication application being blocked from directly communicating with the first communication application by the first firewall; receiving, at the external communication manager, a request for communication between the first communication application and the second communication application after said first and second registering steps; and instructing, from the external communication manager, the first and second communication applications to initiate and accept direct communications with each-other through the firewall based on the first and second registered communication channel information after said receiving step by instructing the first communication application to transmit, as an opening packet, a null packet from a port associated with the firewall window at the first IP address to a port associated with the second communication application at the second IP address.