[tor-relays] What could cause a huge clock skew (9 days) across Tor restarts - anyone else experienced something like this?

[s7r]

s7r wrote:
>  teor wrote:
>> Hi,
>>
>>> [SNIP]


I have received the email below from Ron off-list, and it was very
useful. Posting it here.

Ron, I have tried to email back but apparently your mail server treats
me as spam and I get bounce back with permanent failure - hopefully you
are still getting fro lists.torproject.org and you can read this:

ronqtorrelays at risley.net wrote:
> Hi!
>
> The torproject mailman server appears to have fallen over. Here's what
I've been trying to send to the list. Hope it helps.
>
> -*"*-.,,.-*"*-.,,.-*"*-.,,.-*"*-.,,.-*"*-.,,.-*"*-.,,.-*"*-
>
>> On Sep 7, 2019, at 04:13, s7r <s7r at sky-ip.org> wrote:
>>
>> after upgrading from 0.4.1.2 to 0.4.2.0, I did an entire system
>> reboot because I also updated some other stuff. So the entire OS
>> restarted, not just Tor daemon
>
> It seems likely that your machine's hardware clock is off. During a
reboot, the system will come up using the hardware clock, then (if
configured to do so) eventually correct the time using NTP.
>
> You can check the hardware clock by running 'hwclock' as root. If it's
off, you can set it to your (presumed accurate) system time by executing
'hwclock --systohc'.
>
> --Ron
>

Hey Ron,

Wow! Nice catch. You are right.

Here is what the OS where Tor is running is showing:

$ sudo hwclock
2019-08-28 22:42:11.880025-0400

$ date --utc
Sat Sep  7 23:35:43 UTC 2019

So `date` is accurate while `hwclock` is obviously not.

The problem is I really don't know why. The server above (which reports
skewed clock on hwclock) is a virtual machine.

The host (on which this virtual machine is running) also uses NTP and
reports accurate clock on both `date` and `hwclock`. There is no skew at
all anywhere on the host. So I am wondering where is it getting the
inaccurate hwclock from. Most probably a bug in the virtualization
software used I guess.

All other virtual machines (guests) on the same host report accurate
time on both `hwclock` and `date`. Anyway, certainly the bug is not
related to Tor.

Thanks for this.

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