[ntp:questions] WARNING: someone's faking a leap second tonight

demonccc at gmail.com demonccc at gmail.com
Wed Aug 1 17:36:15 UTC 2012


All,

I found that: http://www.greyware.com/kb/kb2012.717.asp

One of my internal NTP servers has the leap flag set to 01. The fake leap second issue was produced in the servers where this NTP server is the time source preferred, so I guess that it was my problem.

In order to check the leap flag I used ntpq.

First I checked what is the preferred NTP server with the "peers" command.
After that I ran the "associations" command in order to obtain the assids of the NTP servers. When I had the assids, I check the status of the NTP servers using the "pstatus" command (usage: pstatus ASSISD_NUMBER). In the "pstatus" output I saw that the "leap" flag is set to 01.

$ ntpq
ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+ntp0.example.net 76.20.162.121    3 u  783 1024  377    0.296    2.173   0.772
*ntp1.example.net 187.35.120.100   3 u  943 1024  377    0.339   -1.158   0.481
 LOCAL(0)        .LOCL.          10 l  10h   64    0    0.000    0.000   0.000
ntpq> associations
ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1 12345  9424   yes   yes  none candidate   reachable  2
  2 12346  963a   yes   yes  none  sys.peer    sys_peer  3
  3 12347  8043   yes    no  none    reject unreachable  4
ntpq> pstatus 12346
associd=123456 status=9424 conf, reach, sel_candidate, 2 events, reachable,
srcadr=ntp1.example.net, srcport=123, dstadr=192.168.10.1, dstport=123,
leap=01, stratum=3, precision=-20, rootdelay=124.969, rootdisp=63.766,
refid=187.35.120.100,
reftime=d3c3d39e.c685fc7f  Wed, Aug  1 2012 16:11:10.775,
rec=d3c3d7ac.5f9dfe79  Wed, Aug  1 2012 16:28:28.373, reach=377,
unreach=0, hmode=3, pmode=4, hpoll=10, ppoll=10, headway=0, flash=00 ok,
keyid=0, offset=2.173, delay=0.296, dispersion=15.264, jitter=0.772,
xleave=0.012,
filtdelay=     0.30    0.33    0.30    0.36    0.35    0.35    0.35    0.30,
filtoffset=    2.17    2.01    1.80    1.68    1.49    1.25    1.14    1.00,
filtdisp=      0.00   15.75   31.91   47.49   63.14   78.63   94.43  109.95
ntpq> quit
$

Regards.



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