Subject: [Ntp] Antw: [EXT] Éric Vyncke's No Objection on draft-ietf-ntp-using-nts-for-ntp-23: (with COMMENT)

From: "Ulrich Windl" <[email-masked]>
Date: Wed, 11 Mar 2020 08:15:19 +0100

>>> Éric Vyncke via Datatracker <[email-masked]> schrieb am 10.03.2020 um
15:00
in Nachricht
<13478_1583848844_5E679D8C_13478_72_1_158384881593.15262.11708402472633059534@ie
fa.amsl.com>:
[...]
> == COMMENTS ==
> 
> -- Section 1.1 --
> Authentication is of course a desirable property but I would have assumed 
> that
> the time accuracy is even more important. A shift in time -- even minor -- 
> by
> one compromised party would even be more important.
> 
> -- Section 1.2 --
> Does NTP have a "a broadcast mode" or "a multicast mode" ? Notably as the
> former does not exist for IPv6 ;-)
> 
> Is it really true that "it is harmless for stateless servers to process
> replayed packets" as it will have an impact on the server CPU even if
> stateless. Obviously, a DoS on a stateless server is less effective but 
> writing
> "harmless" is too strong IMHO.

Stateful and stateless servers have to drop such packets after inspection,
causing CPU load in both cases.
I think in general high CPU load is not considered a harmful effect (as seen
from the protocol level), even if that may cause packet drops or packet
delays.

[...]

Regards,
Ulrich