I have a strange problem with one of my servers.
ntpdate fail to work, but debugging shows no errors at all. At first I thought maybe a local or network firewall was blocking UDP port 123, but that is not the case- this server can talk UDP port 123 (the ntp protocol) to the Internet and get answers.
Let me demonstrate the issue.
date -s "30 DEC 2012 02:30:00" - works, so I can successfully set the clock without error.
ntpq -pn pool.ntp.org - works, I do get detailed time data from the timeserver, and proves UDP packets are functioning.
ntpdate -d pool.ntp.org - debug mode works, shows a ton of debug data and shows the current time offset:
30 Dec 02:38:56 ntpdate: step time server 18.104.22.168 offset 228.234554 sec
All looks normal, until:
ntpdate pool.ntp.org - after a 4.7 second pause, it returns:
30 Dec 02:41:29 ntpdate: no server suitable for synchronization found
Similar problem running
ntpd, it does not update the clock.
After ntpd is started,
ntpq -pn results in all refid's forever stuck on
.INIT. which means they cannot sync.
/var/lib/ntp/drift is the driftfile setting in ntp.conf, which is chmod 644 and owned by ntp:ntp, same as all my other systems.
I tried a dozen other ntp time servers, disabled iptables firewall, and confirmed the datacenter is not filtering udp traffic. Any ideas what is stopping ntpd and ntpdate from syncing my clock?
This is CentOS 6.3 x64 on a dedicated server with Intel CPU.