Build Your Own 99 Intranet

Building a Microsoft Windows-based intranet is easy and cheap. Microsoft Windows 95, Microsoft Windows 98, and Microsoft Windows NT all contain the necessary networking capabilities. If you don't want to spend the $99, you can build a free intranet within a single computer. All the code in this chapter will run on this one-computer configuration.

NT File System vs. File Allocation Table

With Windows 95 and Windows 98, you are restricted to one file system, File Allocation Table (FAT—actually VFAT for long filenames). With Windows NT, you choose between NT File System (NTFS) and FAT at setup time. Your intranet will be much more secure if you choose NTFS because NTFS allows you to set user permissions for individual directories and files. Users log on to a Windows server (or to an attached workstation) supplying a user name and password.

Intranet and Internet clients participate in this operating-system security scheme because the server can log them on as though they were local users. Thus you can restrict access to any server directory or file to specific users who must supply passwords. If those user workstations are Windows network clients (as would be the case with a LAN-based intranet), the user name and password are passed through from the user's logon.

Network Hardware

You obviously need more than one computer to make a network. While your main development computer is probably a Pentium, a Pentium Pro, or a Pentium II, chances are you have at least one old computer hanging around. If it's at least a 486, it makes sense to connect it to your main computer for intranet testing and file backups.

You will need a network board for each computer, but 10-megabit-per-second Ethernet boards now cost less than $50 each. Choose a brand that either comes with its own drivers for Windows 95, Windows 98, and Windows NT, or is already supported by those operating systems. To see a list of supported boards, click on the Network icon in the Control Panel and then click the Add button to add an Adapter.

Most network boards have connectors for both thin coaxial (coax) and 10BaseT twisted pair. With 10BaseT, you must buy a hub, which costs several hundred dollars and needs a power supply. Thin coax requires only coaxial cable (available in precut lengths with connectors) plus terminator plugs. With coax, you daisy-chain your computers together and put terminators on each end of the chain.

Follow the instructions that come with the network board. In most cases you'll have to run an MS-DOS program that writes to the electrically erasable/programmable read-only memory (EEPROM) on the board. Write down the values you select—you'll need them later.

Configuring Windows for Networking

After clicking on the Network icon in the Control Panel, you select protocols, adapters (network boards), and services. The screens that appear depend on whether you're using Windows 95, Windows 98, or Windows NT. You must select TCP/IP as one of your protocols if you want to run an intranet. You must also install the Windows driver for your network board, ensuring that the IRQ and I/O address values match what you put into the board's EEPROM. You must also assign an IP address to each of your network boards. If you're not connected directly to the Internet, you can choose any unique address you want.

That's actually enough configuring for an intranet, but you'll probably want to use your network for sharing files and printers, too. For Windows NT, install Client And Server Services and bind them to TCP/IP. For Windows 95 and Windows 98, install Client For Microsoft Networks and File And Printer Sharing For Microsoft Networks. If you have an existing network with another protocol installed (Novell IPX/SPX or Microsoft NetBEUI, for example), you can continue to use that protocol on the network along with TCP/IP. In that case, Windows file and print sharing will use the existing protocol and your intranet will use TCP/IP. If you want one computer to share another computer's resources, you must enable sharing from Microsoft Windows Explorer (for disk directories) or from the Printers folder (for printers).

Host Names for an Intranet—The HOSTS File

Both Internet and intranet users expect their browsers to use host names, not IP addresses. There are various methods of resolving names to addresses, including your own DNS server, which is an installable component of Windows NT Server. The easiest way of mapping Internet host names to IP addresses, however, is to use the HOSTS file. On Windows NT, this is a text file in the \Winnt\System32\DRIVERS\ETC directory. On Windows 95 and Windows 98, it's in the \WINDOWS directory, in a prototype HOSTS.SAM file that's already there. Just copy that file to HOSTS, and make the entries with Notepad. Make sure that you copy the edited HOSTS file to all computers in the network.

Testing Your Intranet—The Ping Program

You can use the Windows Ping program to test your intranet. From the command line, type ping followed by the IP address (dotted-decimal format) or the host name of another computer on the network. If you get a positive response, you'll know that TCP/IP is configured correctly. If you get no response or an error message, proceed no further. Go back and troubleshoot your network connections and configuration.

An Intranet for One Computer—The TCP/IP Loopback Address

The first line in the HOSTS file should be

127.0.0.1       localhost

This is the standard loopback IP address. If you start a server program to listen on this address, client programs running on the same machine can connect to localhost to get a TCP/IP connection to the server program. This works whether or not you have network boards installed.