Subject: [Ntp] Re: NTPv5: Operational use case for server/node identification
From: Danny Mayer <[email-masked]>
To: Sarah Grant <[email-masked]>, Miroslav Lichvar <[email-masked]>
Cc: Hal Murray <[email-masked]>, [email-masked]
Date: Mon, 20 Jul 2026 20:39:53 -0400
List-Id: Network Time Protocol <ntp.ietf.org>

On 7/20/26 6:13 PM, Sarah Grant wrote:
> Thank you both for your feedback. I think the EF length has been addressed, and limiting the size to 8 bits should cap the length.
>
> However I don't understand this:
>
>> On 20 Jul 2026, at 12:01, Miroslav Lichvar <[email-masked]> wrote:
>>
>> If it needs to work in both NTPv4 and NTPv5, yes, that would make
>> sense to me, assuming 255 bytes as the maximum length is sufficient.
>>
>> If it was only for NTPv5 (which allows EF lengths not divisible by 4)
>> the additional length field wouldn't be necessary. The client would
>> know it got everything when the EF in the response is shorter than in
>> the request.
> There isn't an additional length field I don't think. What we've written is not much different than how NTPv5 describes the structure of EFs. Can you please clarify?
>
The Extension Field contains the EF Id and the length of the extension 
field in bytes. The body of the extension field can be of any length but 
it is reasonable to limit the length of this one to something like 8 
bytes or similar.

Danny