Saturday, August 15, 2020

Fedora 32 : Accurate timekeeping with chronyd daemon.

Accurate timekeeping is important in networking because accurate time stamps in packets and logs are required.
In Linux operating systems, the NTP protocol is implemented by a daemon running in userspace.
For Fedora distro, you can choose between the daemons ntpd and chronyd. Today I will show you how to use the chronyd.
The Fedora documentation can be found on the official website.
Let's install and use this:
[root@desk mythcat]# dnf install chrony 
...
[root@desk mythcat]# vim /etc/chrony.conf 
With the vim tool now you can add the In most cases, it's best to use pool.ntp.org to find an NTP server or use servers from your country. Now, I can start and enable the daemons named chronyd and add it to the firewall.
[root@desk mythcat]# systemctl start chronyd 
[root@desk mythcat]# systemctl status chronyd 
● chronyd.service - NTP client/server
     Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor p>
     Active: active (running) since Sat 2020-08-15 12:23:08 EEST; 9h ago
       Docs: man:chronyd(8)
             man:chrony.conf(5)
   Main PID: 10071 (chronyd)
      Tasks: 1 (limit: 11800)
     Memory: 1.0M
        CPU: 93ms
     CGroup: /system.slice/chronyd.service
             └─10071 /usr/sbin/chronyd

Aug 15 12:23:08 desk systemd[1]: Starting NTP client/server...
Aug 15 12:23:08 desk chronyd[10071]: chronyd version 3.5 starting (+CMDMON +NTP>
Aug 15 12:23:08 desk chronyd[10071]: Frequency -13.819 +/- 0.344 ppm read from >
Aug 15 12:23:08 desk chronyd[10071]: Using right/UTC timezone to obtain leap se>
Aug 15 12:23:08 desk systemd[1]: Started NTP client/server.
Aug 15 12:23:13 desk chronyd[10071]: Selected source 78.96.7.25
Aug 15 12:23:13 desk chronyd[10071]: System clock TAI offset set to 37 seconds

[root@desk mythcat]# systemctl enable chronyd 
[root@desk mythcat]# firewall-cmd --add-service=ntp --permanent 
success
[root@desk mythcat]# firewall-cmd --reload 
success
You can use it with chronyc command tool:
[root@desk mythcat]# chronyc sources 
210 Number of sources = 4
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^+ blackmamba-g0.eff.ro          3  10   377   692  -1192us[-1273us] +/-   92ms
^+ corporate1.bluepink.ro        2  10   377   200  -1441us[-1441us] +/-   52ms
^+ static-5-2-155-141.rdsne>     2  10   377   468  +1622us[+1540us] +/-   51ms
^* dummy.upcnet.ro               2  10   377   435  -1221us[-1303us] +/-   57ms
[root@desk mythcat]# chronyc tracking
Reference ID    : 4E600719 (dummy.upcnet.ro)
Stratum         : 3
Ref time (UTC)  : Sat Aug 15 19:06:18 2020
System time     : 0.000439648 seconds fast of NTP time
Last offset     : -0.000081712 seconds
RMS offset      : 0.000591977 seconds
Frequency       : 13.753 ppm slow
Residual freq   : -0.000 ppm
Skew            : 0.235 ppm
Root delay      : 0.069966756 seconds
Root dispersion : 0.017129980 seconds
Update interval : 1036.2 seconds
Leap status     : Normal
[root@desk mythcat]# chronyc activity
200 OK
4 sources online
0 sources offline
0 sources doing burst (return to online)
0 sources doing burst (return to offline)
0 sources with unknown address