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Ghost in the Mac Mini

(flickr/orwellianrob)


How a Mac Mini with parental controls gave my family the scare of our lives

In the wee hours of the morning while everyone is fast asleep, the quiet is broken by a deep, booming male voice. It reverberates in my subconscious. I wake and check the house. Nothing. I could have sworn I heard someone talking. Everything is quiet. I’m so tired I immediately fall back to sleep.

The voice penetrates my subconscious again. I stand up, blearily walking the halls. Nothing. Again. Still tired. Back to bed.

Then it comes a third time. More insistent. Urgent even. I shoot straight up, wide awake, ready for anything. I hear the voice clearly as it begins an ominous countdown. 10, 9….

I race through the house. Listening for the voice. It’s in the den. 8, 7…

It’s coming from the computer. I turn on the screen to see what is so urgent. 6, 5….

It won’t show anything. I stab at the mouse to wake up the display. 4, 3….

And it’s … it’s … the logout screen. The parental controls are telling me I have 2, 1, 0 seconds. It logs out the user.

It was the parental controls which I set to lock the computer overnight. Why did it do that? The computer downstairs is set up the same way and it never does that.

From then on we carefully checked that computer before going to bed to make sure the speakers are off. But sometimes we miss it. Once, I was out-of-town and my wife had the scare of her life waking to that deep, calm male countdown.

I had to find out what was happening. I changed settings. Managed permissions. Tested again and again. Absolutely nothing I did stopped the countdown upstairs nor triggered the countdown downstairs. The machines were identical except one was intent on scaring us to death.

After pondering it for quite a while I finally realized there was a difference between machines — the display. Downstairs the mini is attached to a TV. Upstairs it’s attached to a monitor.

Why is that important?

The TV does not turn off automatically when the mini tells it to. The energy saving features on the mini had to be turned off so the screensaver would always run, protecting the TV if it was left on. We must manually turn off the TV.

The upstairs monitor does turn off when told to by the mini. We had it shut off the screen after 10 minutes, but the mini never sleeps so I could have it perform backup tasks overnight.

The downstairs mini thought the screen was on, so when it displayed the warning it was going to log out, it assumed that a user was there to see it. The upstairs machine knew the screen was off so it needed to tell us that it was logging out.

It’s a reasonable assumption on the part of the programmers. I’m sure there were many discussions on what it should do under different circumstances. I’m even certain they were pleased with their solution.

And maybe, just maybe, they secretly hoped it would scare the living daylights out of an unsuspecting family.