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Re: [Ntp] [EXT] Re: NTPv5 KISS code support

Miroslav Lichvar <mlichvar@redhat.com> Wed, 08 November 2023 08:51 UTC

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Date: Wed, 08 Nov 2023 09:51:16 +0100
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Hal Murray <halmurray+ietf@sonic.net>
Cc: NTP WG <ntp@ietf.org>
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Subject: Re: [Ntp] [EXT] Re: NTPv5 KISS code support
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On Wed, Nov 08, 2023 at 12:44:34AM -0800, Hal Murray wrote:
> > The server needs to respond to some constant percentage of the requests and
> > select them randomly. The attacker would need to send requests at a much
> > higher rate in order to overload the network or the server to actually reduce
> > the rate of responses that the victim gets. Doing that for a larger number of
> > servers like pool.ntp.org would be impractical. 
> 
> If we let 25% of the bad traffic through, we have opened up the server for use 
> as a reflector. 

A very poor reflector. The attacker can send the packets directly to
the target to avoid losing 75% of the traffic.

> The bad guy will just have to find 3 other servers to get the 
> same amount of traffic through.

That doesn't change anything if they reflect only 25% of traffic.

-- 
Miroslav Lichvar

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