>> The "listening" services are less of a concern, since the firewall
>> wouldn't permit any incoming connections to be passed through to start
>> with.  It's the "phone home" style services, like time sync, Samba name
>> lookups on microsoft servers, and such, that are more concerning, and
>> privacy-busting.
> The paranoid part of me (which is about 95% of me) half-suspects that NTP
> is actively monitored by the powers that be, to keep tabs on us
> security-minded Linux geeks.
> There's been enough major security bugs in NTP, that one must wonder if
> they're akin to the heartbleed/rng/SSL/etc. compromises that don't
> necessarily look like innocent mistakes.
> Qubes is good at trying to get dom0 to push the time to the VM's by its
> own means.  And if you set the ClockVM to sys-whonix, say, you remove, or
> at least greatly reduce, the ability of TPTB to track your setting your
> clock.  :)
> However, as mentioned, the default of using NTP time syncing is enabled by
> default in the Debian-8 template, which defeats that protection for Debian
> Appvms, unless you disable it in the template.  Just an oversight, I'm
> sure.  (No sarcasm, for once.)
> My PC's RT clock might drift by a few seconds each week, if that; I'm not
> sure why time synchronization has to be so damn frequent and aggressive. 
> A red flag for the paranoid.  :)
> I have a RS232 GPS dongle that spits out the time with 1-second accuracy
> (or atomic-clock level accuracy, if you use the 1-second clock-tick signal
> available on one of the chips, which I have done, lol).
> I plan on hooking that up to my Qubes setup in the near future, and
> disabling network-based clock sync all together.
> (Until Qubes 4.0 comes out, forces me to upgrade to a newer motherboard
> with no RS232 support. :) )
> Might be a good open-sourced hardware project.  I think I've seen some out
> there already, although not necessarily integrated smoothly into Qubes.
> Just one more hole to make sure we plug.
> JJ

You might find Jake Appelbaum's tlsdate interesting, or Adam Langley's
Roughtime.  Both are quite a bit more secure than NTP, although tlsdate
doesn't work with TLS 1.3, and Roughtime is still a proof of concept.


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