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This topic comprises 2 pages: 1 2
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Topic: Booth internet access?
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 04-30-2014 04:58 PM
quote: Mike Blakesley
Why are they expensive? I have a $29 clock/weather station thing in my bedroom that is not even connected to wi-fi but it still connects to the "master clock" in the cloud somewhere and updates itself and is 100% accurate all the time. Why can't these $20,000 servers do that?
Well, NTP is actually exactly this, instead of fitting all machines with their own atomic clock, we sync it to a large bunch of atomic clocks (like those in GPS satellites). It's actually a very nifty protocol, it compensates for most timing defects, latency issues and it is also reasonably capable of protecting you from abuse (like some evil third party trying to skew your clock). It dates back from before we were all surfing the web, has its roots in UNIX and has quite a proven track record. It has some security issues though and it is being used in DDoSes lately, that's why you do not want to expose your own NTP services to the world, you just want to use "the world" as your reference clock. Also, the original (and still best idea) of NTP is that you run one or two NTP servers on your local network which are then being used by all your clients on that network to sync with. Nowadays, it's pretty much overkill to use a dedicated server for NTP, many routers and firewalls can be NTP servers too, or you can run it as a service on another server. This NTP server, in turn, synchronizes with the servers in the cloud.
If you set up this correctly, there are almost zero security implications, no nasty firewall hacks needed and all your machines do run (yeah, ALMOST) exactly the same time. There is also very little maintenance involved.
quote: Frank Cox
I'm frankly a bit surprised that NTP is allowed. I'm not a NTP expert but wouldn't it be possible to set up a "fake" NTP server to gradually shift the time on a server and/or projector? Which then creates it a security hole in the key system.
The whole DCI security model relies on keys being valid during a certain period of time. It's not like the KDM automatically transforms once it becomes valid and self destructs once it expires, so they tied it to a timer. They're only capable of pulling this off, because of the Pandora's Box design of the media block.
I already mentioned it, but if you do NTP correctly, it will not allow you to shift the clock beyond certain limits. But even that doesn't matter.
Like Harold already mentioned, the media block maintains its own clock. It even has a separate battery to power this clock. That's the only time that matters for your KDM. Since this clock on your media block isn't totally accurate, you're indeed allowed to make small corrections, with some predefined maximum adjustments in a given year.
If the clock in your media block somehow skews too much off track because of e.g. a battery failure or inaccurate timer, your hardware becomes a support case...
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