[ntp:hackers] A stop-gap authenticated time service

Magnus Danielson magnus at rubidium.dyndns.org
Mon Nov 9 22:12:12 UTC 2015


Hi,

On 11/09/2015 08:22 AM, Poul-Henning Kamp wrote:
> --------
> In message <563FD918.7050806 at rubidium.dyndns.org>, Magnus Danielson writes:
>
>> You can still yank it with asymmetric delay attacks.
>
> Read again :-)
>
> I don't look into the RTT at all (for that and other reasons).
>
> What you can do is increase my uncertainty window.
>

RTT would actually give you a hint about what is going on.
If you create a slowly increasing asymmetric delay, very slow. That 
phase ramp on your experienced delayed timestamp shifts your apparent 
time. It will appear as if your local oscillator had that frequency error.

Cheers,
Magnus


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