View source for 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.