===== Chrony as NTP service =====
First update the /etc/chrony.conf
[root@fedora22 ~]# cat /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
pool 2.fedora.pool.ntp.org iburst
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
# In first three updates step the system clock instead of slew
# if the adjustment is larger than 10 seconds.
makestep 10 3
# Enable kernel synchronization of the real-time clock (RTC).
rtcsync
# Allow NTP client access from local network.
#allow 192.168/16
# Serve time even if not synchronized to any NTP server.
#local stratum 10
# Specify file containing keys for NTP and command authentication.
keyfile /etc/chrony.keys
# Specify key number for command authentication.
commandkey 1
# Generate new command key on start if missing.
generatecommandkey
# Disable logging of client accesses.
noclientlog
# Send message to syslog when clock adjustment is larger than 0.5 seconds.
logchange 0.5
# Specify directory for log files.
logdir /var/log/chrony
# Select which information is logged.
#log measurements statistics tracking
If you want to use you linux as NTP server, add the following line (all are required):
local stratum 10
port 123
allow
Enable chrony service:
[root@fedora22 ~]# systemctl enable chronyd
[root@fedora22 ~]# systemctl start chronyd
[root@fedora22 ~]# systemctl status chronyd# systemctl status chronyd
[root@fedora22 ~]# systemctl status chronyd.service
chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
Active: active (running) since mer. 2015-08-26 16:49:45 CEST; 51min ago
Main PID: 809 (chronyd)
CGroup: /system.slice/chronyd.service
└─809 /usr/sbin/chronyd -4
août 26 16:49:44 fedora22 systemd[1]: Starting NTP client/server...
août 26 16:49:44 fedora22 chronyd[809]: chronyd version 2.1.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +DEBUG +ASYNCDNS +IPV6 +SECHASH)
août 26 16:49:45 fedora22 chronyd[809]: Frequency -2.945 +/- 0.062 ppm read from /var/lib/chrony/drift
août 26 16:49:45 fedora22 systemd[1]: Started NTP client/server.
août 26 16:49:57 fedora22 chronyd[809]: Selected source 46.29.177.18
août 26 16:49:57 fedora22 chronyd[809]: System clock wrong by -0.605560 seconds, adjustment started
Use chronyc to check the status of the service:
[root@fedora22 ~]# chronyc sourcestats
210 Number of sources = 2
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
46.29.177.18 20 11 32m +0.016 0.415 +8403ns 277us
sns2.papa-razzi-networks. 17 11 33m -0.281 0.420 +7687us 213us
[root@fedora22 ~]# chronyc sources
210 Number of sources = 2
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^* 46.29.177.18 2 9 377 6 +31us[ +59us] +/- 30ms
^- sns2.papa-razzi-networks. 2 9 377 261 +7575us[+7597us] +/- 189ms
[root@fedora22 ~]# chronyc tracking
Reference ID : 46.29.177.18 (46.29.177.18)
Stratum : 3
Ref time (UTC) : Wed Aug 26 15:31:59 2015
System time : 0.000028182 seconds fast of NTP time
Last offset : +0.000028324 seconds
RMS offset : 0.003814944 seconds
Frequency : 2.944 ppm slow
Residual freq : +0.004 ppm
Skew : 0.345 ppm
Root delay : 0.013559 seconds
Root dispersion : 0.018800 seconds
Update interval : 518.4 seconds
Leap status : Normal
Check a particular NTP server (like **ntpdate** command)
[root@fedora22 ~]# systemctl stop chronyd
[root@fedora22 ~]# chronyd -q 'server 10.10.10.1 iburst'
2021-02-12T09:36:28Z chronyd version 3.4 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +SECHASH +IPV6 +DEBUG)
2021-02-12T09:36:28Z Initial frequency -84.650 ppm
2021-02-12T09:36:33Z System clock wrong by 0.003007 seconds (step)
2021-02-12T09:36:33Z chronyd exiting
[root@fedora22 ~]# systemctl start chronyd