Numbering (and naming)

Half the pain of dealing with TCP/IP networks is setting up connections between numbers, names, and machines. Although most people connect on the Internet using names (, for instance), there are always numbers underlying those names someplace. Setting up your own little network means that you get to deal with the numbers - and connect them, pretty much by hand, to the names.

First, the numbers. IP addresses are 32-bit numbers, usually written out as four numbers separated by periods, for instance There are three sizes of networks: A, B, and C. If the first number is below 128, the network is a class A network, a gigantic address space capable of holding millions of computers. Class B addresses start with numbers between 128 and 191, and can hold tens of thousands of machines. Class C addresses start with numbers from 192 to 223, and can hold about 250 machines. I'm not going to go into detail here about what these network addresses mean or the intracies of subnets (you can break them into smaller pieces.) For that, I highly recommend Craig Hunt's TCP/IP Network Administration. All that you need to know for a micronetwork is how to pick numbers that will work.

If you plan on connecting this micronet to a larger net later, you might want to ask your administrator or Internet service provider for a valid Internet address so you don't have to reconfigure your system later. If you want to apply for an IP address directly, contact the InterNIC, the Internet authority on such things. Most likely (they did with me) they'll tell you to leave them alone and contact a service provider or use a private address space. They're running out of space until a new extended system of IP addresses can be created and implemented, hopefully soon.

The easiest numbers to use are the private address IP numbers. Even if you are connected to the Internet, all traffic from these numbers will simply get dropped and never retransmitted - great for security if a bit inconvenient when you do connect. Even if you don't think you'll ever connect to the Internet, it makes sense to use these numbers - it's just one less thing to worry about. The class A private network number is; class B privateaddresses are all addresses from to; and class C private addresses are all addresses from to For a micronet, I recommend using class C. You aren't ever going to need thousands of machines, and you'll have fewer weird possibilities to worry about. Pick your favorite number from 0 to 255 and make your network IP address 192.168.your number.0. For your private network's subnet mask, use, which will work fine on any class C network.

Naming is a lot easier. For local use only you can pick whatever you want. Try to use what you'll use in the final product, as long as you'll be confined to your own local network and don't have to worry about disrupting someone else's site. Personally, I call my machine hypeserve and the network domain, giving me an overall address of (This only matters if you set up a nameserver - more later.) Now that we have these numbers (I'll use as my network address for the rest of these examples), we have to set up the machines. The Mac is much easier, so I'd advise that you start with that.

Back to the instructions outline

Copyright 1995 by Simon St.Laurent. All rights reserved. You may print this document for yourself or others at no charge, but commercial distribution without permission is prohibited.

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