Configure Linux NTP

Users who create a Virtual Server with Rocky Linux or Oracle Linux via the Samsung Cloud Platform Console need additional configuration for time synchronization (NTP:Network Time Protocol). For other standard Linux images (RHEL, Alma Linux, Ubuntu), NTP is already configured, so no extra setup is required.

Installing NTP Daemon

You can configure NTP by installing the chrony daemon. To install the chrony daemon, follow the steps below.

1. Check whether the chrony package is installed by using the dnf command as the root user on the OS of the Virtual Server.

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   dnf list chrony

   dnf list chrony

   • If the chrony package is installed, the following result is displayed.

[root@scp-test-vm-01 ~] # dnf list chrony
Last metadata expiration check: 1:47:29 ago on Wed 19 Feb 2025 05:55:57 PM KST.
Installed Packages
chrony.x86_64                              3.5-1.0.1.el8                                              @anaconda

[root@scp-test-vm-01 ~] # dnf list chrony
Last metadata expiration check: 1:47:29 ago on Wed 19 Feb 2025 05:55:57 PM KST.
Installed Packages
chrony.x86_64                              3.5-1.0.1.el8                                              @anaconda

2. If the chrony package is not installed, install the chrony package using the dnf command.
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   dnf install chrony -y

   dnf install chrony -y

Configuring NTP Daemon

To configure the chrony daemon, follow these steps.

1. Open the /etc/chrony.conf file using a text editor (e.g., vim).
2. Add the following content to the /etc/chrony.conf file and save it.

server 198.19.0.54 iburst

server 198.19.0.54 iburst

3. Use the systemctl command to configure the chrony daemon to start automatically.

systemctl enable chronyd

systemctl enable chronyd

4. Restart the chrony daemon using the systemctl command.

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   systemctl restart chronyd

   systemctl restart chronyd

5. Run the chronyc sources command with the “v” option (display detailed information) to check the IP address of the configured NTP server and verify whether synchronization is in progress.

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   chronyc sources -v

   chronyc sources -v

   • When you run the chronyc sources command, the following result is displayed.

[root@scp-test-vm-01 ~] # chronyc sources -v

210 Number of sources = 1



  .-- Source mode   '^' = server,   '=' = peer,   '#' = local clock.

 / .- Source state     '*' = current synced,   '+' = combined ,   '-' = not combined,

| /    '?' = unreachable,   'x' = time may be in error,   '~' = time too variable.

|| .- xxxx [ yyyy ] +/- zzzz

||                      Reachability register (octal) -.                        |  xxxx = adjusted offset,

||                      Log2(Polling interval) --.          |                    |  yyyy = measured offset,

||                                                     ＼        |                   |  zzzz = estimated error.

||                                                        |       |                   ＼

MS Name/IP address                  Stratum   Poll   Reach   LastRx   Last    sample

=========================================================================

^* 198.19.0.54                                 2      6     377      52      -129us[  -128us] +/-     14ms

[root@scp-test-vm-01 ~] # chronyc sources -v

210 Number of sources = 1



  .-- Source mode   '^' = server,   '=' = peer,   '#' = local clock.

 / .- Source state     '*' = current synced,   '+' = combined ,   '-' = not combined,

| /    '?' = unreachable,   'x' = time may be in error,   '~' = time too variable.

|| .- xxxx [ yyyy ] +/- zzzz

||                      Reachability register (octal) -.                        |  xxxx = adjusted offset,

||                      Log2(Polling interval) --.          |                    |  yyyy = measured offset,

||                                                     ＼        |                   |  zzzz = estimated error.

||                                                        |       |                   ＼

MS Name/IP address                  Stratum   Poll   Reach   LastRx   Last    sample

=========================================================================

^* 198.19.0.54                                 2      6     377      52      -129us[  -128us] +/-     14ms

6. Run the chronyc tracking command to check the synchronization metrics.
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   [root@scp-test-vm-01 ~] # chronyc tracking
   Reference ID        : A9FEA9FE (198.19.0.54)
   Stratum              : 3
   Ref time  (UTC)     : Wed  Feb  19  18:48:41  2025
   System time         : 0.000000039 seconds fast of NTP time
   Last offset            : -0.000084246 seconds
   RMS offset           : 0.000084246 seconds
   Frequency            : 21.667 ppm slow
   Residual freq        : +4.723 ppm
   Skew                  : 0.410 ppm
   Root delay           : 0.000564836 seconds
   Root dispersion     : 0.027399288 seconds
   Update interval      : 2.0 seconds
   Leap status           : Normal

   [root@scp-test-vm-01 ~] # chronyc tracking
   Reference ID        : A9FEA9FE (198.19.0.54)
   Stratum              : 3
   Ref time  (UTC)     : Wed  Feb  19  18:48:41  2025
   System time         : 0.000000039 seconds fast of NTP time
   Last offset            : -0.000084246 seconds
   RMS offset           : 0.000084246 seconds
   Frequency            : 21.667 ppm slow
   Residual freq        : +4.723 ppm
   Skew                  : 0.410 ppm
   Root delay           : 0.000564836 seconds
   Root dispersion     : 0.027399288 seconds
   Update interval      : 2.0 seconds
   Leap status           : Normal