[ntp:questions] Very rapid polling

Danny Mayer mayer at ntp.org
Wed Feb 11 03:51:16 UTC 2009


Eric wrote:
> On Mon, 9 Feb 2009 14:07:26 -0800 (PST), jlevine <jlevine at boulder.nist.gov>
> wrote for the entire planet to see:
> 
>> In the last few days I have seen an increasing number of systems that
>> are requesting the time in NTP format several times per second. 
> 
> Have you considered the possibility that they are spoofed queries from a
> botnet?  There are some records of which IPs are the current/past targets.
> 
> There have been a number of recent DDoS attacks using spoofed UDP packets.
> The usual attack uses port 53 (DNS) and attempts to get 'amplification' of
> a small query into a large response towards the victim IP.  NTP packets are
> the same size both ways, but might still be used to help with a flood.
> 
> The only mitigation I can think of here is for NTP to not respond to
> excessive rate queries at all, or very infrequently, after the KOD.
> 
> - Eric

That's what the latest code does.

Danny



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