[dnsdist] DynBlockRulesGroup > setQueryRate not triggered

denis.machard at orange.com denis.machard at orange.com
Mon Sep 13 09:36:25 UTC 2021


I am trying to implement dynamic block rules in the dnsdist (1.6.0) with the basic following configuration

local dbr = dynBlockRulesGroup()
dbr:setQueryRate(500, 20, "Exceeded query rate", 60)

function maintenance()

After some tests with a client sending 1000qps for more than 20 sec, I see that my dynamic rule is never triggered :(
But if I change the maximum rate from 500 to 499 then the dynamic rule works fine.

I don't find anything in the documentation about this limitation, but after some investigation, my conclusion is that the "rate"  argument of the setQueryRate function has a maximum value not to be exceeded.

maxRate = (The maximum amount of queries in the ringbuffer /  Number of seconds the rate has been exceeded)  - 1

Could you confirm  that my understanding is correct?
If yes , perhaps it will be nice to have some notes in documentation about that, or I just missed it ?

By the way, many thanks for this great product!


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