[ntp:questions] NTP on RHEL4: one works, one doesn't

Christina Plummer chpr at bridge.cc.rochester.edu
Fri Apr 7 18:32:17 UTC 2006


Hello all,

I apologize if this ends up being stupid, but I can't figure out what's
going on.  I have a new RHEL 4 system with ntp-4.2.0.a.20040617-4
installed from Red Hat.  I am just trying to get it to sync its clock with
other NTP servers.

It has the same ntp.conf, and is on the same subnet, as another system
running the same version of RedHat and ntp.  The iptables are the same (I
even tried adding explicit ACCEPT rules for ntp, but that didn't seem to
matter).  The only thing that is different the kernel is 2.6.9-5 instead
of 2.6.9-22.

Here's my ntp.conf - really simple:

============================
server ntp0.cornell.edu
driftfile /var/lib/ntp/drift
============================


Here's what I get in the log when I run 'ntpd -u ntp:ntp -q' on the
failing host:

Apr  7 13:53:17 pm7 ntpd[1020]: ntpd 4.2.0a at 1.1190-r Mon Oct 11 09:10:20
EDT 2004 (1)
Apr  7 13:53:17 pm7 ntpd[1020]: precision = 2.000 usec
Apr  7 13:53:17 pm7 ntpd[1020]: Listening on interface wildcard,
0.0.0.0#123
Apr  7 13:53:17 pm7 ntpd[1020]: Listening on interface wildcard, ::#123
Apr  7 13:53:17 pm7 ntpd[1020]: Listening on interface lo, 127.0.0.1#123
Apr  7 13:53:17 pm7 ntpd[1020]: Listening on interface eth0,
128.151.57.67#123
Apr  7 13:53:17 pm7 ntpd[1020]: kernel time sync status 0040
Apr  7 13:53:17 pm7 ntpd[1020]: frequency initialized 0.000 PPM from
/var/lib/ntp/drift
Apr  7 13:53:34 pm7 ntpd[1020]: no reply; clock not set


It says "no reply", but when I run ntpd with the -d flag, it does in fact
get a response back.  I can see the packets with tcpdump even.



The successful host looks like this:

Apr  7 14:20:35 pm5 ntpd[19110]: ntpd 4.2.0a at 1.1190-r Mon Oct 11 09:10:20
EDT 2004 (1)
Apr  7 14:20:35 pm5 ntpd[19110]: precision = 1.000 usec
Apr  7 14:20:35 pm5 ntpd[19110]: Listening on interface wildcard,
0.0.0.0#123
Apr  7 14:20:35 pm5 ntpd[19110]: Listening on interface wildcard, ::#123
Apr  7 14:20:35 pm5 ntpd[19110]: Listening on interface lo, 127.0.0.1#123
Apr  7 14:20:35 pm5 ntpd[19110]: Listening on interface eth0,
128.151.57.65#123
Apr  7 14:20:35 pm5 ntpd[19110]: kernel time sync status 0040
Apr  7 14:20:35 pm5 ntpd[19110]: frequency initialized -4.304 PPM from
/var/lib/ntp/drift
Apr  7 14:20:44 pm5 ntpd[19110]: synchronized to 132.236.56.250, stratum 2
Apr  7 14:20:44 pm5 ntpd[19110]: time slew -0.000054 s


Any ideas?

Thanks,

  Christina

-------------------------------------------------------------------------
Christina Plummer	       christina dot plummer at rochester dot edu
UNIX Systems Administrator		  Information Technology Services
University of Rochester			 		    (585)275-2239




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