Having been curious for a while, I've decided it's time to start properly playing in the world of packet radio. Not just APRS, though - that's a ‘solved problem’, and quite simple to get a quick hang of.
My main station radio that lives in the hackerspace is a Yaesu FT-7900, and it's a lovely piece of kit. I've got a data cable with proper, separate PTT and audio out/in. It's got a 9600baud mode as well, so hopefully I can get faster data once all of this has been set up.
All the other radios I easily have access to are Baofeng UV5R or UV6B radios, with no proper data interfaces anywhere to be seen! This made experimentation somewhat more difficult than expected.
According to the Direwolf manual, the set up should have been fairly simple - section 5.4.2 ‘Linux AX25’. This walks you through setting up an axport description, and running kissattach. On one machine, I ran into problems at this stage, and had to resort to using socat as a work around - section 18.104.22.168. Once kissattach was correctly set up, a route for the subnet was added and ping was attempted.
Because I've gained an AMPRNET allocation for Aberdeen & North East Scotland (22.214.171.124/24), I'm using IPs on that range. Specifically, I'm using a pair that's been allocated to University of Aberdeen for experimentation in this particular example (126.96.36.199 & 34) as the owner was sat beside me, participating in the test. I could have used any RFC 1918 private IP space, (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 or 188.8.131.52/16), but these were the ones that came to mind first.
After a few failed attempts, it became apparent that both radios could hear each other, but because the Baofeng was using vox to transmit, it was transmitting over any response the FT-7900 was giving.
The experiment was semi successful, in that things shouted at each other and heard each other, but there remains work do be done - specifically building a proper soundcard interface for baofengs with GPIO or serial controlled PTT.