NTP service is stopped, still my CentOS machine is sending out NTP packets to a NTP server:

image attached for reference

# service ntpd status
ntpd is stopped
  • 3
    What version of CentOS is this? Your screenshot is from an Ubuntu system. (And you should copy and paste text and avoid screenshots whenever possible.) – Michael Hampton Sep 13 '19 at 10:22
  • 1
    It also doesn't have to be ntpd, could always be ntpdate or another ntp client or something similar. – Lenniey Sep 13 '19 at 10:45
  • Version is CentOS release 6.7 (Final). – Sachchidanand Upadhyay Sep 13 '19 at 12:16
  • # ntpdate -d 13 Sep 18:51:43 ntpdate[13438]: ntpdate 4.2.6p5@1.2349-o Mon Jan 25 14:08:28 UTC 2016 (1) 13 Sep 18:51:43 ntpdate[13438]: no servers can be used, exiting – Sachchidanand Upadhyay Sep 13 '19 at 13:23
  • @Lenniey Yes its ntpdate which is generating traffic but i was unable to find from which application or location – Sachchidanand Upadhyay Sep 18 '19 at 8:05

In addition to traditional ntpd your system may have an alternative tool installed, configured and running that syncs your clock using the NTP protocol.

"chrony" comes to mind but most likely systemd is synching your clock with ntp, check with

[sudo] timedatectl status

and if that is the case expect an output like the following :

      Local time: Fri 2019-09-13 13:29:18 CEST
  Universal time: Fri 2019-09-13 11:29:18 UTC
        RTC time: Fri 2019-09-13 11:29:18
       Time zone: Europe/Amsterdam (CEST, +0200)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: yes
 Last DST change: DST began at
                  Sun 2019-03-31 01:59:59 CET
                  Sun 2019-03-31 03:00:00 CEST
 Next DST change: DST ends (the clock jumps one hour backwards) at
                  Sun 2019-10-27 02:59:59 CEST
                  Sun 2019-10-27 02:00:00 CET 



After doing more troubleshooting, i found out that one crontab is running with ntpdate which is generating huge ntp traffic:

*/05 * * * * /usr/sbin/ntpdate -u ntp-server-ip

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