Table of Contents
NTP Debugging
https://www.timeanddate.com/worldclock/
https://rags.wordpress.com/2011/10/17/how-to-debug-ntp-issues/
Look at a specific NTP server (without actually resetting time) with the ntpdate command.
ntpdate -d 0.us.pool.ntp.org
ntpd
Config file is in /etc
/etc/ntp.config
ntpq
To quickly show peers
nptq -p
To run in interactive mode:
ntpq
An example of a good NTP session
ntpq> peers
remote refid st t when poll reach delay offset jitter
==============================================================================
+time.cloudflare 10.27.8.67 3 u 60 1024 377 30.157 -0.260 1.974
*173.0.48.220.re 43.77.130.254 2 u 233 1024 377 98.768 4.673 4.253
+vf1.bbnx.net 252.74.143.178 2 u 826 1024 277 107.776 3.096 17.921
-clock.team-cymr 132.163.96.1 2 u 837 1024 377 59.642 -2.689 3.987
The first character in each row indicates the fate of this peer in the clock selection process. The valid characters are:
SPACE Discarded due to high stratum and/or failed sanity checks. x Designated falsticker by the intersection algorithm. . Culled from the end of the candidate list. - Discarded by the clustering algorithm. + Included in the final selection set. # Selected for synchronization; but distance exceeds maximum. * Selected for synchronization. o Selected for synchronization, pps signal in use.
To show associations
ntpq> as ind assid status conf reach auth condition last_event cnt =========================================================== 1 19963 9434 yes yes none candidate reachable 3 2 19964 961a yes yes none sys.peer sys_peer 1 3 19965 941a yes yes none candidate sys_peer 1 4 19966 931a yes yes none outlyer sys_peer 1
The rv command shows more details for an association. To get info on a specific association use “rv 'assid'”
ntpq> rv 19964 associd=19964 status=961a conf, reach, sel_sys.peer, 1 event, sys_peer, srcadr=173.0.48.220.reverse.wowrack.com, srcport=123, dstadr=192.168.100.81, dstport=123, leap=00, stratum=2, precision=-24, rootdelay=20.874, rootdisp=35.629, refid=43.77.130.254, reftime=e25419e2.6ff48f64 Wed, Apr 29 2020 10:21:06.437, rec=e2541dc2.d8214bd8 Wed, Apr 29 2020 10:37:38.844, reach=377, unreach=0, hmode=3, pmode=4, hpoll=10, ppoll=10, headway=0, flash=00 ok, keyid=0, offset=4.673, delay=98.768, dispersion=19.501, jitter=4.253, xleave=0.095, filtdelay= 99.63 98.77 97.12 98.51 118.91 98.62 98.35 95.17, filtoffset= 6.08 4.67 4.72 5.62 15.58 5.72 4.44 2.78, filtdisp= 0.00 15.92 31.82 47.25 63.18 78.65 94.28 109.98
An example of a bad NTP session
ntpq> peers
remote refid st t when poll reach delay offset jitter
==============================================================================
lofn.fancube.co 128.252.19.1 2 u 37m 64 0 0.000 0.000 0.000
mx.danb.email 216.218.254.202 2 u 45m 64 0 0.000 0.000 0.000
mis.wci.com 164.67.62.194 2 u 154 64 104 56.185 8110.21 8110.21
ntp3.junkemailf 216.218.254.202 2 u 1198 64 0 0.000 0.000 0.000
ntpq> as ind assid status conf reach auth condition last_event cnt =========================================================== 1 39351 8033 yes no none reject unreachable 3 2 39352 8033 yes no none reject unreachable 3 3 39353 9064 yes yes none reject reachable 6 4 39354 8073 yes no none reject unreachable 7
ntpq> rv 39351 associd=39351 status=8033 conf, sel_reject, 3 events, unreachable, srcadr=lofn.fancube.com, srcport=123, dstadr=198.89.126.181, dstport=123, leap=00, stratum=2, precision=-20, rootdelay=22.675, rootdisp=27.863, refid=128.252.19.1, reftime=e2540b8e.030f1a31 Wed, Apr 29 2020 14:19:58.011, rec=e2540df7.90dbfac8 Wed, Apr 29 2020 14:30:15.565, reach=000, unreach=13, hmode=3, pmode=4, hpoll=10, ppoll=6, headway=0, flash=1400 peer_dist, peer_unreach, keyid=0, offset=0.000, delay=0.000, dispersion=15937.500, jitter=0.000, xleave=0.030, filtdelay= 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00, filtoffset= 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00, filtdisp= 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0
The flash codes in the rv command output give the reason for the ntp source to get rejected :
flash=1400 peer_dist