The only way I could get a working clock on Debian is by using NTP to sync the clock as described here.
Is there a way to have a reliably accurate clock without NTP and without any Internet connection?
After preventing various autostarting software, blocking kdeconnectd from getting launched (in KDE), and only allowing needed Internet connections in the nftables firewall
sudo lsof -i shows me
ntpd is nearly the only Internet connection left besides Firefox.
I'm interested in better ways than using NTP in general but I'd also like to minimize attack surfaces and even without any potential vulnerabilities and no log-keeping by the NTP servers, having over a dozen of concurrent Internet connections whenever using the computer and being online is a risk to anonymity and privacy (correlating online time data).
Moreover, being required to use NTP to make the clock work means you're dependent on having an internet connection for a working clock which is another reason I'm curious about this.
It would be strange if this is not possible with computers when this been working for decades with often very little offset for wristwatches and so on.
Maybe this is possible using some cheap hardware you can plug on a mainboard or various specific mainboards. I'm most interested in a way to have a local time-source not requiring any radio signals that is low-cost (you can't plug the Deep Space Atomic Clock onto your mainboard, nor a mechanical clock which can sometimes have <5 s offset for a decade).