Difficulties adding IPv6 server with chronyd to the pool

Server operators
1

This weekend I replaced my ten year old Xeon based Stratum 1 server with a Stratum 1 server based on the Raspberry Pi. I am very happy with the power usage going back from 89 Watt to just a few Watt :smile: The reference clock didnā€™t change: it is still the original Garmin 18LVC GPS. I used chronyd instead of ntpd because it was pre-installed in the Linux image I used. The image is the Centos 7 ARM image BTW, not the more common Raspbian image because all my Linux servers are Centos based and I like to use the same tools and configuration on all servers independent on the underlying hardware.

On IPv4 there is just a small dent in the graph as you can see at https://www.ntppool.org/scores/80.127.147.170

As the new server supports IPv6, I also wanted to add this address to the pool. When adding the server domain name ntp4.ipv6.linocomm.net to the pool, the system however responds with the message ā€œCould not check NTP statusā€.

I can access the NTP server over IPv6 from my other servers in the field, so basic connectivity doesnā€™t seem to be a problem. But so many things changed with the move from the old to the new server that it is somewhat difficult to track down the issue.

Any hints where I should start to debug this issue?

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2

Have you tried adding the server to the beta site and see if it gets recognized there?

https://web.beta.grundclock.com/en/

I did a dig and saw the AAAA record, and even used a 3rd party site to query your ntp server so it is definitely accessibleā€¦

Iā€™m sure Ask will chime in today, he usually responds pretty quickly on this forumā€¦

4

I tested this with ntp2.tdc.fi. Itā€™s a dual-stacked NTP server but not in the pool (I had no intention to add it, of course), and looks like IPv4 testing works but IPv6 gives that ā€œCould not check NTP statusā€ message. Iā€™d say @ask will need to check this.

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5

Whoops ā€“ the upgrades this weekend moved the service thatā€™s doing the checking. While moving it I did a new compile with upgraded dependencies, it looks like the IPv6 check broke. Iā€™ll fix it tonight.

The underlying service is https://trace2.ntppool.org/ntp/ with the IP address appended.

7

Just light up ipv6 on my network and ran into the same ā€œCould not check NTP statusā€ problem trying to add an ipv6 address.

8

It should be fixed now; thank you for the report (and your patience)!

Iā€™d updated some of the dependencies for the code that does this check and I needed to remove an earlier work around for having IPv6 work.

10

Oh, geez. I only tested the fix on my laptop. The particular server I moved this daemon to had a bungled network configuration from a while ago when we had trouble with a new firewall and were testing if it was an MTU problem (it wasnā€™t, but this particular system was left with a smaller MTU).

Iā€™ve added monitoring for the trace.ntppool.org daemon to check that it can test v4 and v6 IPs.