Author Archives: Tom

Synapse matrix homeserver with systemd

I run a Matrix homeserver and until recently I was using the virtualenv + synctl method to start the service, which they describe in the README. What I really wanted was to put it into systemd so that I can … Continue reading

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An ARP Server in Rust – Linux Raw Sockets

Linux has a fiddly but useful C interface for sending and receiving raw network packets. It’s documented primarily in the packet(7) manpage and the workhorse of this interface is a struct called sockaddr_ll. It’s ostensibly a type of sockaddr but … Continue reading

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Improving ARP performance on slow AX.25 links

Recently I’ve been setting up TCP/IP connections over VHF radio. They are Linux systems linked by 1200 baud AX.25 modems. Opinions vary as to whether the overheads of TCP/IP are worthwhile at 1200 baud—9600 is certainly better—but it’s handy and … Continue reading

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Making the CW filter work on an FT-817ND

I recently ordered a lovely 500 Hz mechanical filter to use for CW on my FT-897 and FT-817—the YF-122C. I was baffled for much of this week because I could not make it work in the FT-817. If I changed … Continue reading

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