Operation of the Internet Extender

The Internet Extender is a DOS based program designed to function as an Internet Gateway Router that performs Network Address Port Translation. The program must be used in an multi-homed machine, or a machine with two network interface adapters connecting to separate networks. The two possible configurations are:

1.) Connected to the Internet through a Modem
2.) Connected to the Internet through a Network Interface Card

The program must be loaded in the same way for both modes. The DOS packet drivers must be loaded for both devices in the multi-homed system. If a modem is used to dial-up an ISP, a PPP driver must be loaded that will dial the ISP, receive the IP address, bind the address to the modem, and terminate but stay resident (TSR).

If a Network Interface Card is used to connect to a cable modem, T1, T3, etc. and ultimately to the Internet, then an Ethernet Packet driver must be loaded, which in much the same way allows the adapter to communicate with the network it is connected to. The same type of driver is used to connect the local NIC to the local area network. Once both packet drivers are loaded, the Internet Extender is now ready to be loaded.

The Internet Extender uses a configuration file called NAPT.INI to read the statically set IP address of the NIC used on the local network, and Internet NIC if a modem is not used (DHCP is not supported at this time). It also reads the packet driver interrupt (PDI) for both adapters on the system and uses them to send and receive information to and from there respective networks.

Another option that can be specified in the NAPT.INI file is to statically map servers that reside on the Local network to ports that can be accessed by the global Internet. This function operates in much the same way as a proxy server, but the machines on the local network are oblivious to its existence. The local machines treat the Internet Extender as a Gateway machine to the Internet.

Each local client/server machine need only enter the IP address of the local side of the Internet Extender as their gateway, and use the Internet as usual. The Internet Extender will translate the addresses to and from the Internet. No other configuration is necessary. Download the Internet Extender Manual (10KB Text File)