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Re: [Ntp] Antwort: Re: The trick to timestamp with authentication

Philip Prindeville <philipp@redfish-solutions.com> Mon, 07 December 2020 18:17 UTC

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From: Philip Prindeville <philipp@redfish-solutions.com>
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Date: Mon, 07 Dec 2020 11:17:10 -0700
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References: <20201207105406.GF2352378@localhost> <doug.arnold@meinberg-usa.com> <BEF7C4D9-81CD-42AD-BA06-433D45C0DCD1@meinberg-usa.com> <20201203233634.15F7940605C@ip-64-139-1-69.sjc.megapath.net> <12C6B0FF-8C20-4363-AF41-FDF98B2D8072@meinberg-usa.com> <OF24F50CB5.1E226959-ONC1258637.0049B781-C1258637.0049B784@ptb.de> <20201207135001.GJ2352378@localhost>
To: Miroslav Lichvar <mlichvar@redhat.com>
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Subject: Re: [Ntp] Antwort: Re: The trick to timestamp with authentication
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> On Dec 7, 2020, at 6:50 AM, Miroslav Lichvar <mlichvar@redhat.com> wrote:
> 
> On Mon, Dec 07, 2020 at 02:25:11PM +0100, kristof.teichel@ptb.de wrote:
>>   But having unauthenticated corrections just makes it easier for the
>>   attacker, because writing a false correction might be less effort than an
>>   actual delay attack.
> 
> I'd say it is the opposite. Delaying a packet is not that difficult.
> For example, you can generate traffic in order to increase queueing
> delays in switches/routers.


Such an attack would be much more likely to have a widespread impact, and hence more detectable.


> In a MITM attack you need to prevent the original packet sent by the
> client or server reaching the other host. If you can do that, is it
> easier to sent a modified packet than just waiting a bit before
> sending the captured packet unmodified? I don't think there is a big
> difference.
>

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