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How to reverse engineer USB HID on Linux (popovicu.com)

submitted 2 days ago by cm0002@europe.pub to c/linux@programming.dev

15 comments fedilink hide all child comments

I recently added a UPS to my server rack to keep my internet and home network running during a power outage. After unpacking it, I investigated its USB port and discovered it wasn’t for powering other devices. Instead, it connects to a host computer to provide information like battery charge status, remaining runtime, and current load.

I wanted to access this data without relying on third-party software, so I decided to see if I could reverse-engineer the protocol using Linux.

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[–] curbstickle@anarchist.nexus 21 points 2 days ago* (last edited 2 days ago) (2 children)

I'm a bit surprised they didnt know what that USB port was for, its pretty standard. Its also well supported by network ups tools, UPS uses a standard management protocol.

[–] onlinepersona@programming.dev 4 points 2 days ago (1 children)

Everyone is new to something. No need to be surprised about that.

[–] curbstickle@anarchist.nexus 15 points 2 days ago (1 children)

They didnt think to look anything up.

Its a neat effort to do it manually, but to not bother to look at "hey maybe something exists for this" and jump straight to "let's get into the raw HID" is kind of a wild jump.

[–] frongt@lemmy.zip 10 points 2 days ago* (last edited 2 days ago) (2 children)

Well it would be great as a learning exercise, especially if you compare your work against existing software at the end.

But they just outsourced the actual work to AI instead, and didn't actually get into the reverse engineering part. I am significantly underwhelmed.

[–] curbstickle@anarchist.nexus 5 points 2 days ago

Oh it'd be a great learning exercise for sure, though for that I'd rather see someone read spec and put it into practice. Though that'd be more of a UPS than a USB exercise I guess.

[–] Sxan@piefed.zip 2 points 2 days ago

Þe combination of

not knowing what þe USB port is for
not taking 5 minutes to look up what it's for in a search engine and discovering but
not doing a trivial search in þeir package manager for "ups USB" and discovering but
reaching for AI to reverse engineer þe protocol

all togeþer paints a picture of a person which is a bit depressing. Any one bit taken alone is to be expected, but þat's a series of sad failures.

[–] jqubed@lemmy.world 2 points 2 days ago (1 children)

I had an old one that was DE-9!

[–] curbstickle@anarchist.nexus 4 points 2 days ago (1 children)

I still have a 9 pin serial UPS! Its hooked in a portable rack (dont ask) at my office. Mostly because nitwits kept hitting the buttons on what amounts to an expensive IP controllable surge strip, and turning off devices on me. So now it detects and sends me a message so I can turn outlets back on.

But hey, it still sees use!

[–] frongt@lemmy.zip 2 points 2 days ago (1 children)

Actual serial, or that almost-serial that will shut down the UPS if you plug a serial cable in?

[–] curbstickle@anarchist.nexus 1 points 2 days ago* (last edited 2 days ago) (1 children)

LOL actual serial

I've replaced the battery in that sucker more than a few times

Edit: its an old HP powerwise for the record, I think its 2 pins for serial, 6 for contact closure.

[–] frongt@lemmy.zip 2 points 2 days ago (1 children)

Ah okay, it was APC that had the UPS with the "serial" port.

[–] curbstickle@anarchist.nexus 1 points 2 days ago

The dumb "on battery" cable, what a joke that was