Configuring the NTP client at the command line

The NTP client enables the appliance or virtual machine to synchronize its internal clock with an NTP server on your network or on the internet. You can also configure the NTP client through the UI (the preferred method). For more information, see Performing time synchronization.

To configure the NTP client, you must be logged in to the command line as the root user.

1. Edit the /etc/chrony.conf file.

2. Search for the lines beginning server.

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

3. Replace the server entries with the IP address or hostname of the NTP server or servers with which you want to synchronize. For example:

   server ntp.tideway.com
   server 172.17.1.24

4. Save the file.

5. Configure the NTP client service to start when the appliance boots. Enter:

   [root@london01 ~]# /bin/systemctl enable chronyd.service
   Created symlink from /etc/systemd/system/multi-user.target.wants/chronyd.service to /usr/lib/systemd/system/chronyd.service.
   [root@london01] #
   

6. Check to ensure that this change has been made correctly. Enter the following command and ensure that the output is the same as that shown:

   [root@london01] # /bin/systemctl is-enabled chronyd.service
   enabled 
   [root@london01] #

7. Start the service. Enter:

   [root@london01] # /bin/systemctl start chronyd.service
   [root@london01] #

8. Ensure the service is running. Enter:

   [root@london01 ~]# /bin/systemctl is-active chronyd.service
   active
   [root@london01 ~]# 

   The NTP client is now running and needs no further attention.

Rebaseline the appliance after configuring the NTP client

If you use appliance baseline, you must rebaseline the appliance as the tidway user after making this change:

/usr/tideway/bin/tw_tripwire_rebaseline

For more information about tripwire and baselining the appliance, see Baseline configuration.