apt install chrony
yum -y install chrony

systemctl status chronyd
systemctl enable chronyd

Kontrolle ob NTP im Sync ist und mit welchem Server

root@server:~# chronyc tracking
Reference ID    : 91.206.8.34 (svn.mediainvent.at)
Stratum         : 3
Ref time (UTC)  : Wed Feb 19 12:53:08 2020
System time     : 0.000287476 seconds fast of NTP time
Last offset     : +0.000015262 seconds
RMS offset      : 0.000174217 seconds
Frequency       : 21.064 ppm slow
Residual freq   : -0.000 ppm
Skew            : 0.008 ppm
Root delay      : 0.029967 seconds
Root dispersion : 0.017685 seconds
Update interval : 1044.1 seconds
Leap status     : Normal

Anzeigen aller NTP Source die konfiguriert sind

root@server:~# chronyc sources
210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^+ ns5.nosuchhost.net            2  10   377   575  +2977us[+2992us] +/-   44ms
^* svn.mediainvent.at            2  10   377   518  -8927us[-8912us] +/-   55ms
^+ 37.252.187.111                3   9   377   332  +5534us[+5534us] +/-   56ms

/etc/chrony.conf oder /etc/chrony/chrony.conf

server 0.at.pool.ntp.org iburst
server 1.at.pool.ntp.org iburst
server 2.at.pool.ntp.org iburst
server 3.at.pool.ntp.org iburst

stratumweight 0
driftfile /var/lib/chrony/drift
makestep 10 3
logdir /var/log/chrony

Erklärung:

• server – this directive used to describe a NTP server to sync from.
• stratumweight – how much distance should be added per stratum to the sync source. The default value is 0.0001.
• driftfile – location and name of the file containing drift data.
• Makestep – this directive causes chrony to gradually correct any time offset by speeding or slowing down the clock as required.
• logdir – path to chrony’s log file.

NTP Zeit sofort und hart auf den aktuellen Stand bringen

chronyc makestep