THE STORY:

Two servers, one connected directly to the Internet, the other behind the first one (and using it as a NAT router / firewall).

Both run ntpd.

The outer one synchronises fine, and gets to be stratum 3.

The inner one, however, remains on stratum 16, even after half an hour, despite "ntpdc peers" showing the outer server as a fully reachable peer. And we can manually run ntpdate against fear-int, and it works fine.



alaric@infatuation$ ntptrace
localhost.: stratum 16, offset 0.000000, synch distance 0.011955
alaric@infatuation$ sleep 1800 ; ntptrace
localhost.: stratum 16, offset 0.000000, synch distance 0.039855
alaric@infatuation$ ntpdc
ntpdc> peers
     remote           local      st poll reach  delay   offset    disp
=======================================================================
=fear-int        192.168.3.2      3   64  377 0.00011 -0.327713 0.00461
ntpdc> q
alaric@infatuation$ ntptrace
localhost.: stratum 16, offset 0.000000, synch distance 0.066660
alaric@infatuation$ less /etc/ntp.conf 
alaric@infatuation$ cat /etc/ntp.conf | grep -v '^#'
pidfile         /var/run/ntpd.pid
driftfile       /var/db/ntp.drift
logconfig       -syncstatus
tos             minsane 2
server fear-int