The idea
Closed networks still need correct time. Logs, certificates, and anything that compares timestamps get unreliable without it. If there’s no path to an internet time server, the network needs its own.
The build
- Raspberry Pi 400, running headless
- Raspberry Pi OS with NTP
- Serves time to the devices on the closed network
Why bother
When you’re troubleshooting, you line up events from several devices. If their clocks disagree, the timeline lies to you.
Consistent beats perfect
On a closed network, every device agreeing on the time matters more than that time being perfectly accurate. A shared clock that’s a little off still gives you a timeline you can trust. Clocks that disagree with each other don’t.
Still to figure out
- Drift. With no internet reference, the Pi’s own clock drifts over time. A real-time clock module or a GPS time source are the obvious next steps.
- Watching it. Right now nothing alerts if the Pi itself stops serving time.
Fun fact: I once missed a game-support appointment because I thought Pacific time was four hours behind Eastern. It’s three. I take time more seriously now.