Ntp

linux / unix

Getting an out of date server back in line.

date; ntpdate <ntpserver> ; date;

Using step tickers.

/etc/ntp/step-tickets should have the servers from the ntpd.conf config.

Some useful commands:

david@cydonia ~ $ ntpq -c pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
-xen0c.10mbit.bi 64.90.182.55     2 u  844 1024  377   25.870   14.653  15.800
*mircx.com       132.163.4.102    2 u  943 1024  377   61.815    6.705   2.755
+zeus.yocum.org  131.188.3.220    2 u  961 1024  377   27.989    0.981   3.108
+69.42.52.50.scr 128.100.56.135   3 u  435 1024  377   21.985    4.444   0.425
david@cydonia ~ $ ntpq -c as

ind assID status  conf reach auth condition  last_event cnt
===========================================================
  1   764  93a4   yes   yes  none   outlyer   reachable 10
  2   765  96a4   yes   yes  none  sys.peer   reachable 10
  3   766  94a4   yes   yes  none  candidat   reachable 10
  4   767  94a4   yes   yes  none  candidat   reachable 10
david@cydonia ~ $ 

windows

• http://www.meinberg.de/english/sw/ntp.htm compiled ntp.porg for windows.
• cheat sheet: http://www.meinberg.de/download/ntp/docs/ntp_cheat_sheet.pdf
• monitoring tool: http://www.meinberg.de/english/sw/time-server-monitor.htm

Units

1 second (s) = 1000 millisecond (ms)
1 millisecond (ms) = 1000 microseconds (µs)
1 second (s) = 1000000 microseconds (µs)

secure default config

according to gcp

driftfile /var/lib/ntp/ntp.drift
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
server metadata.google.internal iburst
restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited
restrict 127.0.0.1
restrict ::1
restrict source notrap nomodify noquery

See Also

• http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html
• all about how to use GPS device as a source in ntp: http://blog.doylenet.net/?p=145
• Chrony