To whom it may concern.

Hi guys,

This morning I checked some of pool servers and I found that a few clients
send enermous amount of NTP requests.
I decided to limit the rate of this traffic by iptables.
I applied these rules:

-A INPUT --protocol udp --dport ntp --match hashlimit --hashlimit 100/hour 
--hashlimit-mode srcip --hashlimit-name ntp_ratelimit --jump ACCEPT
-A INPUT --protocol udp --dport ntp --match limit --limit 5/min --jump LOG 
--log-level debug --log-prefix "Dropped, NTP ratelimit: "

Logging is on for diagnostic purposes for a while.
Filtering seems to be working well.

Regards

Gabor
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