[Dovecot] ntpd / Time just moved backwards

[Jim Reid]

On 11 Sep 2009, at 09:06, Frank Elsner wrote:

> Sep 10 21:21:02 seymour dovecot: dovecot: Fatal: Time just moved  
> backwards by 434 seconds. [ ... ]
> Sep 10 21:50:55 seymour ntpd[9104]: time reset +434.824810 s
> Sep 10 21:26:36 seymour ntpd[9104]: no servers reachable

> What might happened? And where to ask also?

This is not a dovecot problem. It's a timekeeping problem. dovecote  
detected that your computer went back in time and didn't like that.  
Check on the NTP mailing lists and web site for more information about  
why your time-keeping failed.

It looks like you have a broken NTP setup. Your NTP daemon decided to  
change your computer's time by 434 seconds. This "never happens". ntpd  
continuously makes lots of small adjustments to the computer's time of  
day clock so that time always goes forward as it synchronises that  
clock to a more reliable and accurate time source. It usually only  
jumps the time by intervals of several seconds or more at boot time  
(or if it's run by hand and forced to do that).

BTW, you seem to be running on a broken operating system too. Good  
ones don't permit time travel. The only way they allow the time of day  
back to be put back is when the system is in a privileged, single-user  
state. Messing with the system clock causes security holes -- eg  
replay attacks --and breaks application software, notably make which  
relies on timestamps.
And as you've just found out, it breaks dovecot too.