Re: [Ntp] I-D Action: draft-ietf-ntp-ntpv5-requirements-01.txt

[Miroslav Lichvar <[e-mail]>]

On Wed, Jan 18, 2023 at 10:04:52AM -0800, [e-mail] wrote:
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Network Time Protocols WG of the IETF.
> 
>         Title           : NTPv5 use cases and requirements
>         Author          : James Gruessing
>   Filename        : draft-ietf-ntp-ntpv5-requirements-01.txt

The new version added the following paragraph:

   An additional identifier mechanism MAY be considered for the
   purposes of client allow/deny lists, logging and monitoring. Such a
   mechanism, when included, SHOULD be independent of any loop
   avoidance    mechanism, and authenticity requirements SHOULD be
   considered. 

It's not very clear to me what feature of the protocol is this
supposed to allow or prevent. Any examples?

In 5.1. there is:
   The risk that an on-path attacker can delay packets between a
   client and server exists in all time protocols operating on
   insecure networks and its mitigations within the protocol are
   limited for a clock which is not yet synchronised.

I think I suggested this before. It would be good to add a requirement
here for the protocol to MUST be able to prevent attackers from
injecting unlimited offsets to the measurements, i.e. not allow the
broadcast mode in NTPv5. We should support only the most secure mode
(client-server).

-- 
Miroslav Lichvar