Re: [Ntp] Circular dependencies

Mark Andrews <marka@isc.org> Sun, 17 January 2021 12:22 UTC

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From: Mark Andrews <marka@isc.org>
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Date: Sun, 17 Jan 2021 23:22:28 +1100
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To: Hal Murray <hmurray@megapathdsl.net>
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Subject: Re: [Ntp] Circular dependencies
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The initial address queries by ntpdate/ntpd/etc at boot time can be done with CD=1  (checking disabled).

For real long term shelf storage the trust anchors for the root will need to be updated. 

-- 
Mark Andrews

> On 17 Jan 2021, at 22:24, Hal Murray <hmurray@megapathdsl.net> wrote:
> 
> 
> marka@isc.org said:
>> In practice DNS does not need precise time.  Implementations know that
>> validators and signers are NOT using precise time. BIND for example signs
>> records with a time stamp a hour in the past and records are supposed to be
>> replaced days before they expire.
> 
> I'm thinking of a different scale on "precise", months or years rather than 
> hours or days.
> 
> The usual example is a device that has been sitting on the shelf for 10 years. 
> The only time it has is when the software was built or installed, just before 
> it was packaged up.
> 
> The telcom guys do that.  (Or did.)  I wouldn't be surprised by military gear 
> with similar time scales.
> 
> I could easily imagine a Raspberry Pi being powered off for a whole summer.  Or a smart fridge being off for half a year if it lives at a summer home.
> 
> Anything with a file system that is operating can update the last-known-time occasionally.  That's good enough for normal certificates if "operating" means turned on once a month, maybe even once a year.
> 
> -----------
> 
> We should collect a list of files/data that need to be updated occasionally.  The obvious ones for this group are root certificates and the time-zone database if you need local time and maybe the leap-second file.
> 
> There is the whole can of worms about the software/protocols still being in use after 10 years.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
>