A few days ago I had ntp setup on my network, and everything was running fine. One node was set to sync with upstream servers, and the rest of the nodes from the one set to sync upstream.
Yesterday I updated from CentOS 6.4 -> 6.5 and now all of the ntp functionality has ceased to operate as expected.
In efforts of trying to debug the situation, I ran the following on the upstream server:
$ -> ntpq -pnd ::1: timed out, nothing received ***Request timed out $ -> ntpq -4 -pnd 1 packets reassembled into response remote refid st t when poll reach delay offset jitter ============================================================================== 2 packets reassembled into response *126.96.36.199 188.8.131.52 2 u 42 64 37 77.742 189.392 14.812 2 packets reassembled into response 184.108.40.206 .GPS. 1 u 44 64 37 73.786 216.082 18.406 2 packets reassembled into response 220.127.116.11 .GPS. 1 u 48 64 37 22.617 189.405 15.996 2 packets reassembled into response 127.127.1.0 .LOCL. 10 l 306 64 20 0.000 0.000 0.000
I get the same results (save for diff ip) on the nodes. It seems, somehow the ntp service is defaulting to ipv6, which I do not have configured. I've read some sites saying to pass -4 to the ntpd service, but how would I do that using chkconfig? Some other readings indicated that I should disable ipv6 via the kernel, but this seems like overkill.
For the sake of completeness, adding config file:
driftfile /var/lib/ntp/drift # Permit time synchronization with our time source, but do not # permit the source to query or modify the service on this system. restrict default kod nomodify notrap nopeer noquery restrict -6 default kod nomodify notrap nopeer noquery # Permit all access over the loopback interface. This could # be tightened as well, but to do so would effect some of # the administrative functions. restrict 127.0.0.1 restrict 10.0.0.0 mask 255.255.192.0 nomodify notrap server 0.centos.pool.ntp.org iburst server 1.centos.pool.ntp.org server 2.centos.pool.ntp.org # In case net access is temporarily down server 127.127.1.0 fudge 127.127.1.0 stratum 10