NOSintro – TCP/IP over Packet Radio

An Introduction to the KA9Q Network Operating System

by Ian Wade, G3NRW



For the purposes of illustration throughout this book, there are many examples of NOS commands which include callsigns, IP addresses and so on. To achieve continuity and consistency from chapter to chapter, it’s useful to present a network showing who’s who. So let’s meet the inhabitants of the hypothetical country of Nosland — see Fig 5-1.

The Nosland network consists of a mixture of ordinary AX.25 stations (the small boxes in Fig 5-1), NET/ROM nodes (middle-size boxes) and NOS TCP/IP stations (the shaded boxes). Stations have callsigns in the following series:

AX.25 stations AX9xxx
AX.25 PBBS stations BB7xxx
NET/ROM nodes NR9xxx
NOS stations NS9xxx


The IP network

The IP network (AMPRnet) is spread over three geographical regions, arbitrarily called Regions 41, 45, and 47. The IP addresses of stations in these regions are of the form 44.199.rr.xx, which breaks down as follows:

44 is the AMPRnet network code.

199 is the country code for Nosland.

rr is the Region code (i.e. 41, 45 or 47).

xx is the station address within the region.

Fig 5-1: The NOSLAND Network.

Star of the show (on whom most examples in this book are based) is Bob, shown near the top of Fig 5-1. His AX.25 callsign (in upper-case letters) is NS9BOB-5, and he has the IP hostname (in lower-case letters), shortened to ns9bob. His IP address is

Bob’s immediate IP neighbours in Region 41 are NS9PAM (via digipeater AX9DGC) and NS9KEN. Through Pam he can talk to Sue in Region 45, and through Ken he can talk to Liz and Jim, also in Region 45.

Bob also talks to NS9MXA, which acts as a mail exchanger gateway. Bob uses this gateway to forward mail addressed to certain specific stations. He also forwards mail to other stations via the general SMTP gateway NS9SGW.

Further, he uses the Domain Name System server NS9DNS, to get IP addresses for stations which are not included in his own IP name-and-address file.


The NET/ROM Network

The ordinary NET/ROM network on the left of Fig 5-1 links Regions 41 and 47, and consists of three nodes, NR9AAA, NR9BBB and NR9ZZZ. These nodes have NET/ROM aliases NRA, NRB and NRZ respectively.

In addition, Bob and Tom run NET/ROM nodes within their NOS stations, using the alias:callsign pairs #BOB:NS9BOB-6 and #TOM:NS9TOM-6 respectively.


The AX.25 Network

There are several stations which run ordinary AX.25. These include digipeaters AX9DGA, AX9DGB and AX9DGC, plus end stations AX9TIM and AX9SAM (AX9DGA and AX9DGB are not shown on this diagram).

Station BB7BBS is a regular AX.25 mailbox, capable of receiving and forwarding mail over the PBBS network. Bob acts as a mail gateway, forwarding mail to and from BB7BBS.



The stations which can talk direct to each other are joined by lines in Fig 5-1. Certain stations function as bridges, routers and gateways, to provide connectivity for other stations which are out of direct range of each other. The Nosland network has been carefully designed to show how to configure each of these stations, to handle just about every forwarding scenario you’ll encounter in practice.



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