nanog mailing list archives

Re: UDP/123 policers & status


From: Steven Sommars <stevesommarsntp () gmail com>
Date: Tue, 17 Mar 2020 17:12:17 -0500

The various NTP filters (rate limits, packet size limits) are negatively
affecting the NTP Pool, the new secure NTP protocol (Network Time Security)
and other clients.  NTP filters were deployed several years ago to solve
serious DDoS issues, I'm not second guessing those decisions.  Changing the
filters to instead block NTP mode 7, which cover monlist and other
diagnostics, would improve NTP usability.

http://www.leapsecond.com/ntp/NTP_Suitability_PTTI2020_Revised_Sommars.pdf

On Tue, Mar 17, 2020 at 11:17 AM Mark Tinka <mark.tinka () seacom mu> wrote:



On 17/Mar/20 18:05, Ca By wrote:




+1 , still see, still have policers

Fyi, ipv6 ntp / udp tends to have a much higher success rate getting
through cgn / policers / ...


For those that have come in as attacks toward customers, we've "scrubbed"
them where there has been interest.

Mark.


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