Feb 8 2010

ntpd: Synchronizing with time server Failed error on VMware ESX 3.5

This question came from my friend who just switched from Windows side of the IT world  into VMware and Linux side . Have you ever noticed on VMware ESX servers that NTP (network time protocol) fails to synchronize even though you have configure ntp server in /etc/ntp.conf file. This error can be fixed easily on VMware ESX servers, this happens because ntp client ports are blocked by ESX server firewall. To troubleshoot this error first check if you have ntp port enabled on VMware ESX server firewall, ntp client uses port 123 (UDP) to communicate with Time server on network.

1. Login as root using ssh onto your VMware server and search for UDP port 123 to see if this port for ntp client is listed on VMware ESX server firewall:

[root@esxhost21 etc]# esxcfg-firewall -q |grep -i “123″

If you see no results then you don’t have ntp port enabled on your VMware ESX port.

2. How to enable ntp client port on VMware ESX firewall

[root@esxhost21 etc]# esxcfg-firewall -e ntpClient

3. Verify if ntpClient port is enabled on VMware ESX firewall

[root@esxhost21 etc]# esxcfg-firewall -q |grep -i ntp

Enabled services: CIMSLP ntpClient LicenseClient sshServer LDAP

NOTE: you will notice ntpClient in Enabled services listing on VMware ESX firewall.

4. Verify the ntp client port is listed in VMware ESX firewall listing

[root@esxhost21 etc]# esxcfg-firewall -q |grep -i “123″

82 6232 ACCEPT udp * * 0.0.0.0/0 0.0.0.0/0 udp dpt:123

If you notice ACCEPT for port (UDP) 123 then this indicated that ntp Client port is enabled on VMware ESX server.

5. Restart ntpd daemon (process) on VMWare ESX server

[root@esxhost21 etc]# /etc/init.d/ntpd restart

Shutting down ntpd:

Starting ntpd:

Share This Post

Related Articles

SocialTwist Tell-a-Friend

LEAVE A COMMENT

Subscribe Form

Subscribe to Blog

Top incoming search terms for this post