this post was submitted on 22 Dec 2025
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Privacy
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Again, what would a printer need a clock for?
Anything that connects to the network needs a synchronized clock with other devices it directly communicates with in order to make sure it’s not being subjected to timing attacks. This has been standard practice for 25 years, maybe more, in the end user world because some high profile computer screw ups made use of it. People with weird systems, off the gridders of olde and ppl still on dial up in the teens had some interesting problems to solve when generally all ISPs got drug kicking and screaming to the table by os updates that made synchronized clocks a non negotiable requirement.
Please explain what kind of timing attacks because what you wrote doesn't make sense in the context of a damn printer.
Server? Sure. Printer? Why can it even access public internet?
I'm not sure why you think any digital device shouldn't know what time it is. It's not leaking any kind of personal information, just literal facts about reality.
Maintaining a shared "now" is actually an interesting problem from a relativistic point of view, considering you need time to communicate what time it is. NTP is a relatively simple protocol with some clever tricks around latency; it is organized by strata which go from very precise, authoritative sources (these are atomic clocks at universities, not the NSA) to various levels of "mirrors", down to within your LAN. It is massively distributed and decentralized by nature, to be able to handle everyone to be in sync without overwhelming a handful of primary clocks.
The end device does not need to be able to talk to the internet at all, just to your router (or designated NTP server if you're into that). It is such an old protocol that it is embedded in most consumer routers, and getting a server running in Linux is literally just install, start. You don't need to connect upstream at all, you can absolutely say "on this network I am the god-clock".
My challenge isn't about NTP but about printer shouldn't be able to communicate with the internet, as it has no need for it.
You said: It's common.
Okay, cool. So is cancer.
Exactly! So why allow the printer to go past it!
Well yeah, me needing to lock down this network properly is why I ran up on this, but also being someone who hates reseting the stove clock after a power out, I wouldn't bat my eye at NTP requests really.