[PLUG] Quick & Dirty NTP monitoring

[JP Vossen <jp@jpsdomain.org>]

For years I've have a cron job like this on my internal time server 
(single line):
	ntptrace | head -n1 | perl -ne 'm/^[\w.]+: stratum (\d+),/ or next; 
print qq(NTP not in sync: $_) if ( $1 > 3 );'

Similar on all my on all my other servers, note the added "2> /dev/null" 
and "$1 > 5" instead of "$1 > 3":
	ntptrace 2> /dev/null | head -n1 | perl -ne 'm/^[\w.]+: stratum (\d+),/ 
or next; print qq(NTP not in sync: $_) if ( $1 > 5 );'

All these do is look at the first line of 'ntptrace' output and make 
sure it says either:
	stratum 3		# time server
	stratum 4		# other servers

If not, I get an error message via email from cron.  Simple, no 
monitoring framework needed.

Over the years I've gotten various "foo: timed out, nothing received" 
errors, and if I get enough I'd add that server to the ignore list.  But 
now, since the 2012-12 NTP reflection attacks [1], I'm getting way too 
many timeouts, so I had to the the "2> /dev/null" part to my time server 
cronjob.  That should ignore the errors and if my time server is 
"stratum 3" I'm happy.

So...  Anyone have a better quick & dirty method for this?  And if not, 
steal this one...

Later,
JP

[1] http://isc.sans.edu/diary.html?storyid=17300
----------------------------|:::======|-------------------------------
JP Vossen, CISSP            |:::======|      http://bashcookbook.com/
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