Defcon status at a hosting company


[Aaron] has been working at iweb hosting for about 5 years. When he started, the number of servers was small enough that managing them was fairly painless and could be done by just manually verifying that everything was operational. As the number of servers grew, this task became more and more difficult. They employed various methods of tracking problems, but found them all lacking in one way or another. They got an idea to build a Defcon status page based on all of the information collected about their server status. The page was built and all rejoiced. As with most projects, they just couldn’t leave it alone. Next, they built an android app to be able to see the defcon status from their phones. As cool as that was, they felt they needed to have yet another way to keep track. They What you see above is the prototype for the office defcon status display. It is extremely simple, using an Arduino (yes, we know, massive overkill) to receive status updates to change the display number. [Aaron] says that right now it is a mess, and you have to shield it from the light with your hands to see it, but it works. What should the next step be? A giant Alpha Numeric LED indicator? A nixie tube?


  1. The Moogle says:

    why the hell is he using transistors?
    total fail lol

  2. Xargle says:

    Oh come on! That’s crap! No hardware detail, no software detail plus crap design == not an article.

  3. Buzzkill says:

    For a better display you could output to a betabrite. There is a piece of code for the betabrite that will let you display a static “Defcon Level X”. It is currently a backyard baseball game app for the betabrite but you could take that and should be able to drive the sign from an arduino. add some documentation please!

  4. [H]ackerK says:

    a GIANT nixie tube would be cool haha

  5. Aaron Brady says:

    [hackerk] – Yeah, nixie tubes or maybe a VFD would be good.

    [moogle] – The Arduino can source 20ma for driving an LED, but this display is common anode, not common cathode – you need to sink current, not source it, so I’m using the transistors to pull the pins to ground.

    I didn’t actually expect this to be posted; the entry is more about monitoring than hardware; I’m happy to put up a schematic, but it’s basically a 1:1 ratio of transistors to pins.

  6. The Moogle says:

    screw that tiny crap display
    use one of these :)

  7. Agent420 says:

    agreed – BetaBrites are fairly cheap on ebay and easy to interface.

    I’ve got a betabrite sign displaying pc status on my wall mounted pc aka Colossus.

  8. Agent420 says:

    oops forgot photo

  9. vic says:

    The obvious next step would be to use an ethernet shield or equivalent and make a standalone device :-)

    (I’m currently working on an ethernet device so it’s maybe obvious only to me ;P)

  10. Agent420 says:

    @ Aaron Brady
    avr chip can sink 20ma per io pin, so there should be no problem and you can get rid of the transistors.

    in fact, it is much more common to handle io logic by sinking than sourcing (in most cases, logic lines are held high by external pullups resistors). this just means your program logic is inverted; ie to turn on an led you turn the port pin ‘off’.

    you’ll still need current limiting resistors for each segment, maybe i’m blind but i don’t see them in your photo… are they built into the 7 seg display?

  11. Agent420 says:

    oops forgot link again…

  12. SWHarden says:

    forget the 7-seg and slap on a VFD similar to×20-vfd-character-display-na204sd02/ and the microcontroller won’t be total overkill. Although, I’d much rather see a single chip used for this project instead of wasting an entire development board by dedicating it to this project. Just toss in your choice of far-simpler AVR microcontrollers, program it directly, and boom! Simple, non-overkill, and cheap.

  13. SWHarden says:

    On second thought, you could use a 4511 CMOS chip attached directly to the 7-seg and power it straight from a parallel port. BOOM! done!

  14. SWHarden says:
  15. Agent420 says:

    nothing wrong with using a dev board for a project that has a limited lifespan. i’d rather use a uc on a dev board than dedicate a pc to the task.

  16. Aaron Brady says:

    Thanks for all the advice; I wasn’t aware that the AVR could sink as well as source, agent420. There’s a current limiting resistor on the anode; this may not actually be enough, perhaps I do need them on each pin? It was a case of “it worked, it’ll do”.

    The 4511 is nice, but really parallel ports are a rare find nowadays. I also like the fact that the Arduino shows up as a class compliant serial port. It saves using parapin and having to run as root. Perhaps a bare AVR with a USB library would be a bit ‘thinner’ than an Arduino, but this was just a two-lunch-time proof of concept.

    @swharden – that was pretty much the first thing that we tagged as a possible for the ‘real thing’.

  17. Odin84gk says:

    24″ tall numbers

    Zigbee transmission, allowing you to place this wherever you want.

    Attach to a strobe light in case it increases to 5. (120 volt strobe light, use the micro to drive the relay)
    Add a Big Red Button to turn off the strobe.

    Twitter or SMS to notify your cell….

  18. Agent420 says:

    ^ Unless you are designing a fixed static led scheme where paralleled leds will not change, you always want to have a current limiting resistor for each led. Using one resistor on the power source wont work well because the current varies as you change the number of leds that are lit.

    refer to the 2313 schematic I posted, that is what you want to do.

  19. blackspyder says:

  20. Sirket says:


    You need to build the Defcon display from War Games.

    Just some relays, light bulbs and mains power if you want to go that route. Either way- seriously cool look for anyone that gets the reference.

  21. Sirket says:

    Bah! blackspyder posted his link after I had already loaded the page and while looking for the damned image!

  22. frollard says:

    imho defcon statusses need to be in bar-graph-thermometer shaped format. More lights = more doom.

  23. metalicaman8 says:

    the next step should be self maintenance

  24. miked says:

    seven segment display made from light tubes. like the ones you plug into your car cigarette lighter (cheap & 12v powered). Defcon 5 adds red strobe.

  25. amk says:

    im guessing you can collect enough data from your servers (sounds like you have quite a few) to generate an 8bit defcon scale. I’d use that data and fade a giant jolly roger from green to red based on server status.

  26. TJHooker says:

    I would of just used a python script, ssh, and xml. It’d take maybe 5 hours to roll out the system.

  27. nebulous says:

    How about a classic (as in, old) feel. Just have a lightbox with 5 lights (flux leds or some such) for the five statuses, with colored plastic with the numeral on it. Add a nice buzzer/noisemaker in the order of the Lost sound, and you’ve got an attention grabber.

  28. Agent420 says:

    ^ what was old is new again ;-) personally I also like the warmth and glow of incandescent over leds.

    id also consider some cool jeweled lens indicators.

    another idea would be one of those modulated neon tubes where you can control the lit length of the tube.

  29. Agent420 says:

    for that matter, a mechanical indicator using a stepper or server would be cool too.

    or an analog display like a meter

  30. rwbthatisme says:

    Nice hack aaron, good to see the old lunchtime projects are alive and well…

  31. Etan says:

    Add audio – “DO YOU WANT TO PLAY A GAME?”

  32. farthead says:

    difficult to keep track of? HUH? They must not have very good managers or techs. BigBrother is what we used for over a DECADE and it works great to let you know what is good/bad or indifferent for hundreds of servers. it used to be free, now you gotta buy it.

  33. peterpiper says:

    Top stuff. I like you’re style!

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