Re: [chrony-users] "clients" command maxes out at 4096

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

On Tue, May 31, 2016 at 07:36:45PM +0000, McDonald, Isaac wrote:
> That makes perfect sense. Seeing as how I'm more interested in how many
> clients are connecting as opposed to what their IP addresses are I'm going
> to hold off on increasing clientloglimit.
> 
> Is there functionality available to report on the number of unique NTP
> clients? If not, where can I submit a feature request?

That depends on what exactly you mean by unique NTP clients. A lot of
public NTP traffic is from ntpdate, which is running periodically,
e.g. from cron. This creates a large group of clients that are
switching randomly between servers and if the pool zone has many
servers, the interval between requests to the same server may be very
long.

The question is for how long should chronyd be able to keep the
addresses in memory to still consider them as active and what is the
clientloglimit value that will allow that. It depends on the incoming
packet rate.

If you wanted to count clients that make at least one request per day,
you would need to make sure most addresses in the client log are not
dropped before that. You could monitor the average "Last" value in
the list of clients. Then you would count the clients that have "Last"
smaller than one day. With the new -c option in chrony-2.4, this could
be a simple awk script:

chronyc -c clients | awk -F , '{ if ($6 < 24 * 3600) c++ } END { print c }'

-- 
Miroslav Lichvar

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