TWC (AS11351) blocking all NTP?

Stephane Bortzmeyer bortzmeyer at
Mon Feb 3 09:52:29 UTC 2014

On Sun, Feb 02, 2014 at 02:49:49PM -0800,
 Matthew Petach <mpetach at> wrote 
 a message of 49 lines which said:

> If NTP responded to a single query with a single equivalently sized
> response, its effectiveness as a DDoS attack would be zero; with
> zero amplification, the volume of attack traffic would be exactly
> equivalent to the volume of spoofed traffic the originator could
> send out in the first place.

It is a bit more complicated. Reflection with amplification is
certainly much less useful for an attacker but it has still some
advantages: the attack traffic coming to the victim's AS will be
distributed differently (entering via different peers), making
tracking the attacker through Netflow/Ipfix more difficult.

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