NOSintro – TCP/IP over Packet Radio

An Introduction to the KA9Q Network Operating System

by Ian Wade, G3NRW



Welcome to NOSintro, the beginner’s guide to running TCP/IP over Packet Radio.

In this book you’ll find a wealth of practical information, hints and tips for setting up and using the KA9Q Network Operating System (NOS). The emphasis throughout is on hands-on practicalities. You’ll see exactly how to install NOS on a PC, how to set up the control files to suit your local environment, how to check out basic operations off-air before going live, and how to use NOS commands for transferring files, logging in to remote systems, sending mail, and so on.

Theoretical coverage is kept to a minimum — there are plenty of other publications describing the minutiae of TCP/IP and related packet protocols if you want to dig deeper. In this book there is just enough theoretical background to provide a framework for the hands-on sessions, so you get a good understanding of what’s happening without being submerged in a morass of superfluous detail.

NOS and related packages such as NET run on all of the well-known families of microcomputers. These include the Apple Macintosh, Amiga, Archimedes, Atari, DEC VAX, IBM PC and Sun, running under MS-DOS, OS/2, VMS and various flavours of UNIX. This book is specifically about the PC version of NOS, but the other versions work in virtually the same way, so almost everything you read here is applicable to those versions as well.

NOS is a complex package, and requires you to set up a number of control files before you can use it. This isn’t a difficult job, but there is quite a lot of work involved. To help get you on the road, this book contains full listings of typical NOS control files, which you can modify to suit your own environment.

Better still, you can obtain a copy of the G3NRW NOSview on-line documentation package for NOS. NOSview contains not only full reference documentation for NOS, but also a complete working set of NOS software. This includes NOS itself and all of the control files listed in this book. You should get hold of NOSview if you can and install it on your PC, as the worked examples in this book relate directly to the files that come with the package. Full details of how to get NOSview are in Chapter 2.

I’ve said that this is a book for beginners to TCP/IP. The level is pitched at people who already know how to drive a PC at the MS-DOS command line, and how to make "ordinary" AX.25 packet radio connections with a conventional terminal node controller (tnc). Experience in sending and receiving messages via an AX.25 packet bulletin board system (PBBS) is also assumed.

In a book of this kind, it’s impossible to explain everything about NOS. NOS is a big, complex package, with many more features than most commercial packages costing hundreds of dollars, and so it’s only possible to scrape the surface here. My main hope is that there is more than enough information to get you started, with plenty of clues as we go along about what to explore next. In fact, the first two drafts of this book were much longer than originally intended, and savage wielding of the scalpel was eventually necessary to bring it down to a reasonable size. Given time, I plan to use some of the excised material in a follow-up book which will cover the advanced capabilities of NOS in much more detail.

NOS originally grew up in the world of amateur radio, but in more recent times it has found its way into "professional" environments as well. If you are a networking professional reading this book, please don’t be misled by the word "amateur". Most of the techniques, the software and the networking infrastructures described here are the work of internationally respected professionals and academics, who also happen to be licensed radio amateurs.

The great attraction of the amateur environment is that people are free to experiment at will, without the constraints of fixed project goals and timescales, or bosses looking over their shoulders. Indeed, many of the techniques which are commonplace in the professional field today were originally developed by amateurs.

There’s certainly nothing "amateurish" about NOS. You can install NOS on your PC in the office and connect into your LAN (or WAN or SLIP link), and you can use ping, ftp, telnet, mail, news, ppp and all the other well-known Internet services in exactly the same way that you probably do now. The big advantage of NOS is that it provides much greater functionality than you’ll find in most commercial packages, and it’s free.

Reading a work of this nature is not a trivial undertaking. The best way to start is to spend an evening speed-reading the whole book from cover to cover, just to get the feel of it. Don’t worry if there are parts you don’t understand — just skip them and move on. Then read the book again, a little slower this time, perhaps taking a week of evenings to do so. If there are sections you still don’t understand, skip them and read on to the end of the chapter. Then go back to the beginning of the chapter and read it again. Don’t be afraid to dip and dive into different parts of the book to fill in the blanks — eventually the whole picture will become clear.

By then you should have a fairly good idea of what TCP/IP and NOS are about. The next step is a must: you must install NOS (ideally with NOSview) on your PC, so that you can try out the commands at first hand. Then read through the book yet again, this time concentrating on the hands-on sessions. Only at this point, when you type in NOS commands and see the results of your actions, will you really begin to understand what’s happening.

All of this takes place with the radio switched off. When you eventually feel confident that you understand most of the capabilities of NOS, you are ready to modify the NOS control files to suit your own environment. You’ll be replacing the dummy radio callsigns, network addresses and other parameters listed in this book with real callsigns, etc, and then you can switch the radio on and try out NOS on-air.

Chances are that if you follow these steps — it may take three or four weeks of spare time before you are ready for live tests — you’ll be rewarded with almost everything working perfectly first time. Now you can login to other stations, transfer files, send mail, forward mail onto the PBBS network, run a NET/ROM node, etc, etc, and very quickly you’ll be hooked! New avenues of exploration will open up, new software will come along to experiment with (TCP/IP is the growth area in networking software development these days), and I guarantee that there will always be something new to learn and try.

What if you can’t make things work? The best people to help are obviously your neighbours who are already using TCP/IP, or you can put out a general bulletin on the PBBS network asking for advice.

If you are still having difficulties, I will be pleased to try to answer your queries. Full contact details follow immediately after the title page of this book. In general I would prefer to receive messages by packet radio or email, but if you write a letter, please enclose an SASE (and IRCs if appropriate) for your reply.

Note that my experience of NOS is with various MS-DOS implementations based on original versions from KA9Q. I haven’t run NOS on any other platform. Therefore if you have specific detailed questions on the other platforms, please address them elsewhere; I don’t want to mislead you with second guesses!



NOSintro is based on the work of many people. In the list below I hope I’ve included all of those who have written NOS software and documentation in the past, and who have played a significant part in the development of the amateur TCP/IP packet radio network throughout the world.

The number one acknowledgement goes, of course, to Phil Karn, KA9Q, the father of NOS. Phil has demonstrated to the world that it’s possible to build a powerful, fully functional multi-tasking communications system, conforming to international networking standards, on the back of a primitive, memory-constrained, single-tasking operating system. It shouldn’t work, but it does.

What’s more, Phil has made his software freely available to the world, and several other people have now used it as a starting point for further development. Without Phil’s contribution, it’s unlikely that the amateur packet network would be anything like as advanced as it is today.

Now the roll call of other major contributors (in last name order):

John Ackermann, AG9V
Hayden Bate, G8AMD
Dave Brooke, G6GZH
Mike Chace, G6DHU
Tom Clark, W3IWI
Mike Dent, G6PHF
D R Evans, G4AMJ/NQ0I
Gary Ford, N6GF
Dan Frank, W9NK
Bdale Garbee, N3EUA
Fred Goldstein, K1IO
Gerard van der Grinten, PA0GRI
Allen Gwinn, NK5CKP
Charles Hedricks
Kelvin Hill, G1EMM
Gareth Howell, G6KVK
Pavel Jalocha, SP9VRC
Brian Kantor, WB6CYT
Anders Klemets, SM0RGV
Wally Linstruth, WA6JPR
Peter Meiring, G0BSX
Russell Nelson
Johan Reinalda, WG7J/PA3DIS
Bill Simpson
Mike Stockett, WA7DYX
Paul Taylor, G1PLT
Dave Trulli, NN2Z
Stanley Wilson, AK0B

If you are missing from the list and feel you should be there, please don’t be offended. Treat it as an inadvertant omission on my part. If you care to drop me a line I’ll be glad to add your name to the credits in the next edition of

Good luck with TCP/IP. You’ll have fun!


Ian Wade, G3NRW

November 1992


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[Copyright 1992-2009 Dowermain Ltd. All Rights Reserved. This page last modified: 21 May 2009]