A note on callsigns, addresses and things before we start

Each AX.25 and NET/ROM port on your system must have a callsign/ssid allocated to it. These are configured in the configuration files that will be described in detail later on.

Some AX.25 implementations such as NOS and BPQ will allow you to configure the same callsign/ssid on each AX.25 and NET/ROM port. For somewhat complicated technical reasons Linux does not allow this. This isn't as big a problem in practice as it might seem.

This means that there are things you should be aware of and take into consideration when doing your configurations.

• Each AX.25 and NET/ROM port must be configured with a unique callsign/ssid.
• TCP/IP will use the callsign/ssid of the AX.25 port it is being transmitted or received by, ie the one you configured for the AX.25 interface in point 1.
• NET/ROM will use the callsign/ssid specified for it in its configuration file, but this callsign is only used when your NET/ROM is speaking to another NET/ROM, this is not the callsign/ssid that AX.25 users who wish to use your NET/ROM `node' will use. More on this later.
• ROSE will, by default, use the callsign/ssid of the AX.25 port, unless the ROSE callsign has been specifically set using the `rsparms' command. If you set a callsign/ssid using the `rsparms' command then ROSE will use this callsign/ssid on all ports.
• Other programs, such as the ax25d program can listen using any callsign/ssid that they wish and these may be duplicated across different ports.
• If you are careful with routing you can configure the same IP address on all ports if you wish.