Amateur Radio
AX-25 Networks for Rookies

by Jamie Saker, W0JRS
w0jrs@arrl.net
Revised February 28, 2001

 

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Section 2: Let's Get Started

Note: I'll use section numbering in this section to help organize the presentation of the material, and assist you as you work through it so you don't get lost!

2.0 The project's OSI model

It's going to be helpful to understand what we're doing in a conceptual sense. There's just too much software we're going to be installing so we need to fit it in where it belongs so you'll have an idea what we're doing.

If you haven't heard of the OSI reference model, it's a paradigm we use in data communications to divide things into theoretical layers. Here's a representation of the model:

(Image courtesy of freesoft.org)

Using the model, let's list where the components we'll be working with go, and then discuss them in section 1.1.

Application Web browser, Telnet application, PMS, etc.
Presentation HTML, XML, ASCII
Session SSL, SSH
Transport TCP and UDP
Network IP, AX-25
Data Link AX-25
Physical TNC, transceiver, cables, wireless frequency

 I'll explain each one of these packages as we go along.

2.1 Download and upgrade the kernel

The first thing we need is our kernel source code. Log into your Linux system, cd to /usr/src and look for a directory called kernel. We're going to end up installing a brand new kernel and configuring it to operate with the required amateur radio extensions in it.

Kernel configuration (especially when done by those not familiar with it) should not be done on systems that contain any required data, systems, applications or other items that would be missed if the system did not recover. If this is your first time messing with kernels, do it on a system designated solely for this purpose (you might get to reinstall it a few times before you get it right). 

[linux-2.2.18 kernel] As of this writing, the current 2.2 kernel is 2.2.18, available at ftp.kernel.org. It is strongly advisable that you read the Kernel FAQ before building kernals, or grab the assistance of a friend who's familiar with Linux kernal installation.

We use the 2.2 kernel because the ax-25 libraries, apps, tools and other resources available are built for the stable 2.2 kernel. As of the writing of this document, 2.3 development kernels and 2.4 stable kernels were available, but ax-25 packages have not yet been revised to support these kernels.

Please read through this completely before attempting, unless you are familiar with kernel installations. As mentioned in the beginning of this document, it is recommended that you conduct this on a "readily sacrificed, virgin Redhat installation." It is possible that you will have to reinstall your Redhat system one or more times before you get your AX-25 system operational.

Installation Steps:

 

2.2 Download and upgrade the ax-25 and supporting packages

Now we're going to add the AX-25 software that interfaces with the kernel modules we just created, allowing us to create an AX-25 networked system. Let's grab a few packages and get them installed. Each of these should compile cleanly on Redhat 6.2 with the upgraded 2.2.18 kernel as installed above. If you have problems installing, you may wish to consult your local Linux expert or review Linux documentation available at www.linux.org. 

By now, you should have your kernal and all of your packages installed and operational. If not, check your steps (and in the worst case scenario, reload Redhat 6.2 and reinstall the kernel and packages). If so, let's start configuring.

References

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