Re: [chrony-users] Reference ID

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> On 28/05/2016, at 10:08 AM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:
> William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
> Physics&Astronomy  |     Advanced Research  |     Fax: +1(604)822-5324
> UBC, Vancouver,BC  |   Program in Cosmology |     unruh@xxxxxxxxxxxxxx
> Canada V6T 1Z1     |      and Gravity       |
> On Sat, 28 May 2016, Bryan Christianson wrote:
>>> This has been argued in the past. The refid is 4 bytes, so it cannot fit in
>>> the whole IPv6 address. And it really is not worth expanding the size of the
>>> refid. For refclocks it is a four character name (translate the bytes to
>>> ascii-- eg PPS0, SHM3...). I am not sure what the algorithm is for ipv6 (last
>>> 4 bytes in the addreess.) I really do not think it is worth Lichvar's time to
>>> rewrite the refid to be 12 bytes say, with all the potential for hidden bugs
>>> introduced by change.  It is not supposed to be an address. It is supposed to
>>> be just a unique id to differentiate the various sources.
>> Sure - I understand not wanting to change the length. That’s why I suggested using an address from one of the IPv4 reserved ranges rather than presenting some random collection of 4 bytes as an IP address.
> Not sure why that would help.
> It is a refid, not an address, in any case. Are you really liable to copy out
> that address and try to contact that machine?
> Where did you see the refid and get confused by it?

I don’t have the specific case available, but when synchronised with and IPv4 server I see the following

root@cora:~# chronyc tracking
Reference ID    : (
Stratum         : 2

The ‘normal’ interpretation of this kind of display would be IP address/host name.

In the case where the hostname resolves to an IPv6 address, you will some some random IPv4 address bearing no relation to the hostname displayed.

As you say it is just an ID and I guess the whole IPv4 representation is an artefact of the early days of NTP.

Maybe it could just be displayed as 8 hex digits.

Bryan Christianson

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