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Re: NTP issue Continued


I haven't followed this thread for long so this may have already been suggested.

I have this line in my iptables file to allow ntp communication. You may already have it, if not add it and restart iptables. This works on both RHAS 3 and RHAS 4. You might check in /var/log/messages for anything concerning ntp, that may give you some clue, also check /var/log/security

Good luck.

#Allow NTP.
-A INPUT -p udp -m udp -s 0/0 --sport 123 -d 0/0 --dport 123 -j ACCEPT

Andrew Bridgeman corusgroup com wrote:

I am still having problems getting 40 redhat machines to use ntp and
synchronise with our Windows 2003 Cluster. I have tried a couple of things
suggested by people but have had no luck in fixing the issue. It seems that
when I put either the IP of the cluster, the name of the cluster or the
fully qualified name of the cluster in the config files the ntp service
communicates with the Windows cluster straight away and all the machines
are synchronised OK. The problem comes when i leave them afterwards for an
hour or a day or even a week and look back at the time on the machines and
they are all different.

I read on the net that the communication used with ntp is UDP over port 123
and was wondering if i have  some kind of polling issue after the initial
start-up of ntp. Does anyone know more detail on how the ntp part works.
i.e How often does is poll the cluster server for the time or is there a
way of checking the communication on that port is working.

Any  help on this would be much appreciated.


Andrew Bridgeman

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