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Until recently, it has been possible to configure Linux to natively support packet. This allowed for the creation of custom “packet servers” without needing specialist software - allowing users to easily run custom applications.

Below is a guide that links back to early 2000's for installing the utilities.

At present the utilities mentioned below are still available in many linux distributions, including Raspbian, but are unstable and cause “kernel panics” rendering them unusable in a production environment. This guide has been retained so that it can quickly be modified and refocused when these issues are resolved.

The aim of this section is not to fully cover the installation and configuration of all the possible ax25 modules. I will attempt to cover a simple installation and configure 2 serial ports as if they had TNC's on them. I will also show what additional configuration the DXSpider program requires.

Please bear in mind that I am basing this section on a RedHat 7.1 distribution, if you are using SuSe or any other distibution then your mileage may vary. I will be happy to make any changes and additions if you email me any errors or distribution specific requirements.

You would probably benefit from reading the AX25-HOWTO which is much more comprehensive and an interesting configuration program is also available called ax25-config which may help you to configure things.

The following files are extracts from the working files at GB7MBC and are in daily use. However, there are many ways that you can configure the ax25 utils, this is just the one I use, it does not mean it is necessarily the best or for that matter, the right way!

There are 2 things you need to do initially. You need to get the 3 files required for the ax25 installation and you need to make some changes to the kernel configuration.

The first thing is to get the versions of the ax25 utils that match your kernel. You may also wish to get a node package of some kind. There are 2 main node packages in use of which I shall keep to the original by Tomi Manninen, OH2BNS as this is included in the ax25 rpms as standard. The other is AWZNode by IZ5AWZ.

NB: The AX25 stuff in 2.4 kernels appears to have been broken until
2.4.18.  I strongly suggest you get at least this kernel.

For 2.4 kernels you need these files…

*libax25-0.0.7-7.i386.rpm

*ax25-tools-0.0.6-13.i386.rpm

*ax25-apps-0.0.4-9.i386.rpm

First you need to add Amateur Radio Support to your kernel. This is a main menu item and should be easily found. Within this header you will find lots of options. For our purposes you need to enable Amateur Radio AX.25 Level 2 Protocol, NET/ROM and the Serial Port KISS Driver. For the purposes of this document I will work under the assumption that you include them in the kernel fully, ie not as modules. If you need to look at compiling your kernel for ax25 more fully, I would refer to the excellent AX25-HOWTO

I should say at this stage that NET/ROM is not mandatory. If you do not use it simply ignore any instruction concerning it.

Now recompile your kernel in the normal way and reboot your system.

Now install the RPM's you downloaded, libax25 first, then ax25-tools, then ax25-apps.

     rpm -ivh libax25-0.0.7-7.i386.rpm
     rpm -ivh ax25-tool-0.0.6-13.i386.rpm
     rpm -ivh ax25-apps-0.0.4-9.i386.rpm

You will find the configuration files in /etc/ax25. These consist of several files …

*axports *nrports *nrbroadcast *ax25d.conf *node.conf

These are the main files. You will find other files but they do not have any use unless you are wanting to use that particular protocol, Rose or axip for example.

NOTE:- before we start it is important to realise that every interface
requires a different SSID.  You should be able to follow this in the
following examples.

This file sets up the ax25 ports you want to use. An example is below for a standard TNC2 …

     #portname   callsign   baudrate   paclen   window   description
      2m         gb7mbc-2   19200      256      2        2m port on 144.900MHz
      4m         gb7mbc-4   19200      256      2        4m port on 70.325MHz

Note that the portnames have to be unique.

The file headings are as follows …

*portname - The name you will refer to the port by *callsign - The ax25 callsign you want to assign to the port *baudrate - The speed you communicate between TNC and computer *paclen - The maximum packet length for ax25 connections *window - The ax25 window parameter. This is like 'maxframe' *description - A textual description of the port

This file sets up the netrom ports you want to use. An example is below and includes a port for both cluster and node. You will see why we need 2 ports later …

#portname   callsign   alias   paclen   description
 netrom     gb7mbc-8   BARE    236      Node Netrom Port
 netrom2    gb7mbc-9   MBCDX   236      Cluster Netrom Port

Note that the portnames have to be unique.

The file headings are as follows …

*portname - The name you will refer to the port by *callsign - This is the callsign that NET/ROM traffic from this

                        port will use

*alias - The NET/ROM alias this port will be assigned *paclen - The maximum size of NET/ROM frames transmitted *description - A textual description of the port

This file sets up the netrom broadcast qualities. An example is below …

     #axport   min_obs   def_qual   worst_qual   verbose
      4m       5         10         100          1

The file headings are as follows …

*axport - The port name in axports that you wish to broadcast

                        NET/ROM on.

*min_obs - The minimum obsolescence value for the port *def_qual - The default quality for the port *worst_qual - The worst quality for the port. Any routes under

                        this quality will be ignored

*verbose - This flag determines whether you will only broadcast

                        your own node (0) or all known nodes (1)

This file controls any incoming ax25 and NET/ROM connections and steers them to the relevant program. There are lots of configuration options you can set here, however they are well covered in the AX25-HOWTO. For our purposes I will show a typical set of parameters. An example is below …

[gb7mbc-0 via 2m]
parameters    2 1   6  900 *  15  0
NOCALL *  *  *  *  *  *  L
default  * * * * * *  - sysop /spider/src/client client %u ax25

[gb7mbc-1 via 2m]
parameters    2 1   6  900 *  15  0
NOCALL *  *  *  *  *  *  L
default *  *  *  *  *  *  0  root  /usr/sbin/node  node

[gb7mbc-0 via 4m]
parameters    2 1   6  900 *  15  0
NOCALL *  *  *  *  *  *  L
default  * * * * * *  - sysop /spider/src/client client %u ax25

[gb7mbc-1 via 4m]
parameters    2 1   6  900 *  15  0
NOCALL *  *  *  *  *  *  L
default *  *  *  *  *  *  0  root /usr/sbin/node  node

<netrom2>
parameters 1    10 * * * 3 *
NOCALL *  *  *  *  *  *  L
default  * * * * * *  - sysop /spider/src/client client %u ax25

<netrom>
parameters 1    10 * * * 3 *
NOCALL *  *  *  *  *  *  L
default *  *  *  *  *  *  0  root  /usr/sbin/node  node

There are a few things to take note of here. Firstly, all ax25 sections are wrapped in [ ] and all NET/ROM sections are wrapped in < >. Secondly you should be able to see that anyone who forgets to set their callsign in a TNC and tries to connect with the standard NOCALL set into their TNC will not connect, the 'L' means 'lockout'. Lastly and importantly, notice the order of the sections. They are all done in interface order.

You should be able to see that the normal line for access to the cluster is like this ..

     default  * * * * * *  - sysop /spider/src/client client %u ax25

however, if you wish your users to be able to use SSID's on their callsigns ..

     default  * * * * * *  - sysop /spider/src/client client %s ax25

For most purposes this is not desirable. The only time you probably will need this is when you need to allow other cluster nodes that are using SSID's in. In this case it would probably be better to use the first example and then add a specific line for that node like this:

     GB7DJK-2  * * * * * *  - sysop /spider/src/client client gb7djk-2 ax25
     default  * * * * * *  - sysop /spider/src/client client %u ax25

For those of you that wish to run the node, you need to set up the node.conf file. There are a couple of additional files, node.perms is very similar to the way ftp permissions are set up in NOS systems and node.motd is the message anyone logging into the node will get. The node.conf file sets all the parameters of the node as you would expect. An example is below …

# /etc/ax25/node.conf - LinuxNode configuration file
#
# see node.conf(5)

# Idle timeout (seconds).
#
IdleTimeout     1800

# Timeout when gatewaying (seconds).
#
ConnTimeout     40000

# Visible hostname. Will be shown at telnet login.
#
HostName        gb7mbc.ampr.org

# ReConnect flag.
#
ReConnect       off

# "Local" network.
#
#LocalNet       44.139.8.48/32

# Command aliases. See node.conf(5) for the meaning of the uppercase
# letters in the name of the alias.
#
##Alias         CAllbook 'telnet %{2:44.17.0.53} 1235 %1 s'
#Alias          CONVers  'telnet %{2:oh2ti} 3600 "/n %u %{1:139}\n/w *"'
#Alias          CLuster  'c hkiclh'
Alias           CONV    "telnet lurpac 3600"
Alias           BBS     "c 70cm gb7crv"
Alias           DXC     "telnet localhost 9000"
Alias           MUD     "telnet homer 4000"
##Alias           TEMP    "finger temp@mary.g6phf"
##Alias           TNOS    "c ip1 gb7mbc-5"
##Alias           TUtor   "telnet gb7mbc 3599"

# Hidden ports.
#
#HiddenPorts    2

# External commands. See node.conf(5) for the meaning of the uppercase
# letters in the name of the extcmd.
#
# Flags:        1       Run command through pipe
#               2       Reconnected flag
#
#ExtCmd         TPM     3       nobody  /usr/bin/finger finger tpm
#ExtCmd         ECho    1       nobody  /bin/echo echo \%U \%u \%S \%s \%P \%p \%R \%r \%T \%t \%\% \%0 \%{1:foobar} \%{2} \%3 \%4 \%5

# Node ID.
#
NodeId          "\nBARE:GB7MBC-1"
#NodeId         \033[01;31m***\033[0m

# Netrom port name. This port is used for outgoing netrom connects.
#
NrPort          netrom

# Logging level
#
LogLevel        3

# The escape character (CTRL-T)
#
EscapeChar      ^T

# Resolve ip numbers to addresses?
#
ResolveAddrs    off

# Node prompt.
#
#NodePrompt     "\n"
#NodePrompt     "%s@%h \%i> "
NodePrompt      "\nBARE:GB7MBC-1 \%i > "

This should be fairly obvious I hope.

Ok, now we have all the relevant files configured, the next step is to get it all running.

The first thing to do is attach the TNC's. Your TNC's should be in KISS mode and connected to the serial ports involved.

You now use the 'kissattach' command to connect the TNC's to the system like this …

     kissattach /dev/ttyS0 2m 44.131.96.199
     kissattach /dev/ttyS1 4m 44.131.96.199

Assuming that 44.131.96.199 is your IP address. The devices ttyS0 and ttyS1 are com1 and com2 respectively. Now we can set some parameters …

     kissparms -p 2m -t 150 -l 150 -s 50 -r 50
     kissparms -p 4m -t 150 -l 150 -s 50 -r 50

The command 'man kissparms' will give you the explanation of the switches.

Now we need to attach the NET/ROM ports in the same way …

     nrattach netrom
     nrattach netrom2

All of the above can be put in a file and called from /etc/rc.d/rc.local. Put all the above commands in a file called rc.ax25 and put a line in rc.local to call it.

Now you can start the daemons that set everything in motion …

     ax25d
     netromd -i

All should now be running. All that remains is to get the node working for telnet connections. If nothing else, this will allow you to connect to the node yourself to check on connection status etc. There are 2 files that need to be edited.

First edit /etc/services and add

     node    3000/tcp     #OH2BNS's Node Software

Assuming you want it to run on port 3000

Now cd /etc/xinetd.d and edit a new file called node. It should look like this …

     # default: on
     #       unencrypted username/password pairs for authentication.
     service node
     {
             socket_type     = stream
             wait            = no
             user            = root
             server          = /usr/sbin/node
             log_on_failure  += USERID
             disable         = no
     }

You now need to restart the xinetd daemon. First find out what the PID is like so ..

     ps auxw |grep xinetd

You will get a reply something like this …

     root       592  0.0  0.1  2256  620 ?        S    Feb07   0:00 xinetd -stayalive -reuse -pidfile /var/run/xinetd.pid

The PID or Process ID is 592 in this case so now we can issue the command …

     kill -HUP 592

All should now be operational and you should be able to log into the node by using a telnet session to the relevant port, like so …

     telnet localhost 3000

If that works, you are just about there. you should (assuming you have radios connected to the TNC's) be able to connect out to other stations and receive incoming ax25 and netrom connections.