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Using an ESX Server host as an NTP server

ESX Server, by default, is not configured to act as an NTP server and does not respond to NTP queries from client machines.

Note: Before you begin please refer to KB1003490 for important information on restarting the mgmt-vmware service.

Before performing the following steps, configure the ESX Server host as an NTP client. For more information, see Installing and Configuring NTP on VMware ESX Server (1339) .

Edit the /etc/ntp.conf file to remove the restrictions preventing client access to the ESX Server host.
1. Make a backup copy of the /etc/ntp.conf file:
  
  cp /etc/ntp.conf /etc/ntp.conf.bk
2. Use an editor such as nano or vi and edit the /etc/ntp.conf file and comment out the following line by placing an asterisk at the beginning:
  
  #restrict default ignore
3. Add a line for each network that accesses the ESX Server host as an NTP source:
  
  restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
4. Save the /etc/ntp.conf file and quit the editor.
Create a custom service for the NTP server on the ESX Server host.

The custom service does not go into the /etc/vmware/firewall/services.xml file. Instead, create a new file in the same directory, such as custom.xml . In this file, place the following, specifying a unique ID.

<ConfigRoot>
<service id='0045'>
<id>ntpServer</id>
<rule>
<direction>inbound</direction>
<protocol>udp</protocol>
<port type='dst'>123</port>
</rule>
</service>
</ConfigRoot>

Caution: Do not keep backups or copies of any files in the /etc/vmware/firewall/ directory as all files in this directory are parsed and duplicates may cause hostd to crash.
Restart the ESX Server Management and NTP services for the changes to take effect:

[root@server root]# service mgmt-vmware restart

[root@server root]# service ntpd restart

NTP Server, ESX Server

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