The software works like in the analogy of a router with NAT sharing internet access within a LAN.
DownloadNAT32® is a Microsoft Windows® application which gives all computers on your private LANs direct Internet access. NAT32 runs only on the computer with the Internet connection and acts as an enhanced IP Router for the other computers on your private networks. The computer running NAT32 retains totally unmodified Internet access, and all applications on that computer will continue to run as before. On your other computers, most of your networking applications will require no reconfiguration, they simply pass all Internet packets to the NAT32 router, which forwards them to the Internet.