ntpdate works, but ntpd can't synchronize
- by dafydd
This is in RHEL 5.5.
First, ntpdate to the remote host works:
$ ntpdate XXX.YYY.4.21
24 Oct 16:01:17 ntpdate[5276]: adjust time server XXX.YYY.4.21 offset 0.027291 sec
Second, here are the server lines in my /etc/ntp.conf. All restrict lines have been commented out for troubleshooting.
server 127.127.1.0
server XXX.YYY.4.21
I execute service ntpd start and check with ntpq:
$ ntpq
ntpq> peer
remote refid st t when poll reach delay offset jitter
==============================================================================
*LOCAL(0) .LOCL. 5 l 36 64 377 0.000 0.000 0.001
timeserver.doma .LOCL. 1 u 39 128 377 0.489 51.261 58.975
ntpq> opeer
remote local st t when poll reach delay offset disp
==============================================================================
*LOCAL(0) 127.0.0.1 5 l 40 64 377 0.000 0.000 0.001
timeserver.doma XXX.YYY.22.169 1 u 43 128 377 0.489 51.261 58.975
XXX.YYY.22.169 is the address of the host I'm working on. A reverse lookup on the IP address in my ntp.conf file validates that the ntpq output is correctly naming the remote server. However, as you can see, it appears to just roll over to my .LOCL. time server. Also, ntptrace just returns the local time server, and ntptrace XXX.YYY.4.21 times out.
$ ntptrace
localhost.localdomain: stratum 6, offset 0.000000, synch distance 0.948181
$ ntptrace XXX.YYY.4.21
XXX.YYY.4.21: timed out, nothing received
***Request timed out
This looks like my ntp daemon is just querying itself.
I am thinking about the possibility that the router-I-don't-control between my test network timeserver and the corporate network timeserver is blocking on source port. (I think ntpdate sends on port 123, which gets it around that filter and is why I can't use it while ntpd is running.) I have email in to the network folks to check that.
Finally, telnet XXX.YYY.4.21 123 never times out or completes a connection.
The questions:
What am I missing, here?
What else can I check to try to figure out where this connection is failing?
Would strace ntptrace XXX.YYY.4.21 show me the source port ntptrace is sending from? I can deconstruct most strace calls, but I can't figure out the location of that datum.
If I can't directly examine the gateway router between my test network and the timeserver, how might I build evidence that it's responsible for these disconnections? Alternately, how might I rule it out?
