Re: [Ntp] NTPv5: big picture

[Miroslav Lichvar <[e-mail]>]

On Mon, Jan 04, 2021 at 06:31:31PM +0100, Dieter Sibold wrote:
> > With most options I think the client can simply send a request using
> > that option and see if the server's response has it. It can do that
> > with every request, or try it only occasionally to reduce the average
> > length of the request and response.
> > 
> > For more complex or conflicting features, the support can be indicated
> > with a flag in an extension field.
> 
> If security-by-default is enforced the NTS-KE could serve as a robust mean
> to exchange the server’s capabilities.

NTS-KE is supposed to be used only rarely (clients should save
cookies and keys), so I don't think it would be a good mechanism for
discovery of the server's capabilities, even if NTS was required by
NTPv5. They can change due to an upgrade or reconfiguration without
breaking the NTS context (requiring new NTS-KE session).

-- 
Miroslav Lichvar