[Solved] Strange NTP time sync problem

[gunnarf]

I have two firewalls running OPNsense. On both of them I have set up ntp time syncronization. On box number 1 I get, if turning off ntp service)
root@OPNsense:~ # ntpdate 193.182.111.12
12 May 12:59:40 ntpdate[13215]: no server suitable for synchronization found

and on this box the service does not work!!! ??? And when staring NTP service I get "No active peers available"

On the other:
root@OPNsense:~ # ntpdate 193.182.111.12
12 May 13:08:27 ntpdate[97654]: adjust time server 193.182.111.12 offset +0.002239 sec

Works as expected.

No strange own rules on neither box!

Gunnar

[gunnarf]

This is how I solved the problem. I have working ipv6 on both boxes, just as a reminder.

If any of the servers in the list of wanted servers, can return an ipv6 address, NTP will stop working. So problem solved by taking away for instance sth1.ntp.se and using the resolved ipv4 address in the list. Even if I had the 2 first servers as ipv4 addresses and the two next as gbg1.ntp.se and mmo1.ntp.se, NTP would fail to find any servers. I replaced all 4 lines with their ipv4 addresses, and NTP is working.

If the error lies within the NTP daemon or the way OPNsense addresses the daemon, is something I won't dig into. But it's sad that using ipv6 causes so many strange errors!