[Pool] Off by a second leap second failures

Ask Bjørn Hansen ask at ntppool.org
Wed Jul 15 16:31:23 UTC 2015

What is the earliest before a scheduled leap second that you can set the flag? I know what ntpd does (or is supposed to), but I thought that strictly speaking you are allowed to set it at the beginning of the leap second month?



On Wed, Jul 15, 2015 at 5:29 AM, Miroslav Lichvar <mlichvar at redhat.com>

> On Mon, Jul 13, 2015 at 01:06:51AM -0700, Ask Bjørn Hansen wrote:
>> > On Jul 10, 2015, at 8:13, Svavar Kjarrval <svavar at kjarrval.is> wrote:
>> > 
>> > Are the server admins notified of the problem and advised on general
>> > solutions? Even if they're kicked out of the pool, they'll probably
>> > continue to serve bad time for others.
>> When a server score goes below 10 (if I remember right) the system sends off an email to tell the operator that something is amiss. Depending on what’s wrong this is usually within 90-120 minutes of the server going sour. If the server continues to be down then every few weeks the system will send you a reminder before (eventually) marking the server deleted and notifying the operator about that.
> What about servers that serve good time and have good score, but are
> still announcing a leap second? Their clients could insert the leap
> second again on the end of the month, or any day actually depending on
> their implementation.
> In my limited monitoring I see about 2% of the servers still have
> leap=01. Interestingly, in Czech Republic it's almost a third of 41
> servers.
> About half of them seem to be running ntp-4.2.6 (not responding to
> port < 123) and probably hit the ntp bug #2246, which Martin has
> pointed out earlier. Restarting ntpd should fix that.
> I suspect the rest are running 4.2.4 or older, which have the design
> flaw that the leap status is set on any day when any of its sources
> is announcing the leap. If two or more such servers are polling each
> other, the status will be passed in a loop and they will get stuck to
> it after the insertion. To fix this some of these servers will
> probably need to be reconfigured to not use any servers currently
> announcing the leap second or at least shut down until the infection
> in the loop they are part of clears up.
> -- 
> Miroslav Lichvar

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