Configuring the Oracle Cloud Infrastructure NTP Service for an Instance

Use the following steps to configure Oracle Linux 7.x instances to use the Oracle Cloud Infrastructure NTP service.

1. Run commands in this section as root with the following command:
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   sudo su -

2. Install the NTP service with the following command:
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   yum -y install ntp

3. Change the firewall rules to allow inbound and outbound traffic with the Oracle Cloud Infrastructure NTP server, at 169.254.169.254, on UDP port 123 with the following command:
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   awk -v n=13 -v s=' <passthrough ipv="ipv4">-A OUTPUT -d 169.254.169.254/32 -p udp -m udp --dport 123 -m comment --comment "Allow access to OCI local NTP service" -j ACCEPT </passthrough>' 'NR == n {print s} {print}' /etc/firewalld/direct.xml > tmp && mv tmp /etc/firewalld/direct.xml

   At the prompt mv: overwrite '/etc/firewalld/direct.xml'?, enter y.

4. Restart the firewall with the following command:
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   service firewalld restart

5. Set the date of your instance with the following command:
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   ntpdate 169.254.169.254

6. Configure the instance to use the Oracle Cloud Infrastructure NTP service for iburst. To configure, modify the /etc/ntp.conf file as follows:
   1. In the server section comment out the lines specifying the RHEL servers:
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      #server 0.rhel.pool.ntp.org iburst
      #server 1.rhel.pool.ntp.org iburst
      #server 2.rhel.pool.ntp.org iburst
      #server 3.rhel.pool.ntp.org iburst

   2. Add an entry for the Oracle Cloud Infrastructure NTP service:

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      server 169.254.169.254 iburst

   The modified server section should now contain the following:

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   # Please consider joining the pool (http://www.pool.ntp.org/join.html).
   #server 0.rhel.pool.ntp.org iburst
   #server 1.rhel.pool.ntp.org iburst
   #server 2.rhel.pool.ntp.org iburst
   #server 3.rhel.pool.ntp.org iburst
   server 169.254.169.254 iburst

7. Start and enable the NTP service with the following commands:

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   systemctl start ntpd
   systemctl enable ntpd

   You also need disable the chrony NTP client to ensure that the NTP service starts automatically after a reboot, using the following commands:

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   systemctl stop chronyd
   systemctl disable chronyd

8. Confirm that the NTP service is configured correctly with the following command:

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   ntpq -p

   The output will be similar to the following:

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        remote           refid      st t when poll reach   delay   offset  jitter
   ==============================================================================
   169.254.169.254 192.168.32.3     2 u    2   64    1    0.338    0.278   0.187
   						

1. Configure a Windows Server instance to use the Oracle Cloud Infrastructure NTP service by doing one of the following things:

   • To configure the NTP service by using Windows Powershell, run the following commands in Powershell as Administrator:

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     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\Parameters' -Name 'Type' -Value NTP -Type String
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\Config' -Name 'AnnounceFlags' -Value 5 -Type DWord
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer' -Name 'Enabled' -Value 1 -Type DWord
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\Parameters' -Name 'NtpServer' -Value '169.254.169.254,0x9' -Type String
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient' -Name 'SpecialPollInterval' -Value 900 -Type DWord
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\Config' -Name 'MaxPosPhaseCorrection' -Value 1800 -Type DWord
     Set-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\W32Time\Config' -Name 'MaxNegPhaseCorrection' -Value 1800 -Type DWord

   • To configure the NTP service by manually editing the registry, do the following:

     1. Change the server type to NTP:
        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\

        2. Click Type.
        3. Change the value to NTP and click OK.

     2. Configure the Windows Time service to enable the Timeserv_Announce_Yes and Reliable_Timeserv_Announce_Auto flags.

        To configure, set the AnnounceFlags parameter to 5:

        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\

        2. Click AnnounceFlags.
        3. Change the value to 5 and click OK.
     3. Enable the NTP server:
        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\

        2. Click Enabled.
        3. Change the value to 1 and click OK.
     4. Set the time sources:
        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\

        2. Click NtpServer.
        3. Change the value to 169.254.169.254,0x9 and click OK.
     5. Set the poll interval:
        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\

        2. Click SpecialPollInterval.
        3. Set the value to the interval that you want the time service to synchronize on. The value is in seconds. To set it for 15 minutes, set the value to 900, and click OK.
     6. Set the phase correction limit settings to restrict the time sample boundaries:
        1. From Registry Editor, navigate to:

           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\

        2. Click MaxPosPhaseCorrection.
        3. Set the value to the maximum time offset in the future for time samples. The value is in seconds. To set it for 30 minutes, set the value to 1800 and click OK.
        4. Click MaxNegPhaseCorrection.
        5. Set the value to the maximum time offset in the past for time samples. The value is in seconds. To set it for 30 minutes, set the value to 1800 and click OK.
2. Restart the time service by running the following command from a command prompt:
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   net stop w32time && net start w32time

3. Test the connection to the NTP service by running the following command from a command prompt:

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   w32tm /query /peers

   The output will be similar to the following:

   #Peer: 1
    
   Peer: 169.254.169.254,0x9
   State: Active
   Time Remaining: 22.1901786s
   Mode: 3 (Client)
   Stratum: 0 (unspecified)
   PeerPoll Interval: 10 (1024s)
   HostPoll Interval: 10 (1024s)

   After the time specified in the poll interval has elapsed, State will change from Pending to Active.