Packet Re-Addressing

The Application Level Gateway unpackages each packet by stripping away the addressing information contained in the packet. It then repackages the data that is left from the packet with the gateway's own addressing information, as if it were the original author of the packet.

The gateway then sends the re-addressed packet on its way. This has the effect of hiding the origin of the packet from the final destination computer.

This destination computer, when it ultimately receives the packet, thinks that the firewall computer is the original author and sender of the packet. It knows nothing of the source computer that is the true original author of the packet.

The addressing information of the source computer was removed when it went through the firewall.