[ratelimits] defaults for DNS-RRL
dot at dotat.at
Thu Mar 7 09:51:57 UTC 2013
Daniel Stirnimann <stirnima at switch.ch> wrote:
> I wonder what default settings other operators are using who have
> DNS RRL applied.
I'm using responses-per-second 2 on my small server, mainly to see how
aggressive I can get without causing problems. At this level it does
sometimes reject legit queries from name server clusters. Other settings
are the defaults.
> // start rate-limiting if more then X identical
> // responses per second, default 5
> responses-per-second 20;
The default is 0, i.e. unlimited.
> // as current attack pattern produce rcode NOERROR we relax
> // rate-limiting for other response rcodes, default 5
> nxdomains-per-second 30;
> errors-per-second 30;
These default to the same as responses-per-second.
> // set to max. of normal query load x WINDOW
> min-table-size 15000;
> // set to max. of query load the server can handle x WINDOW
> max-table-size 1000000;
The documentation suggests that the table size should be about
the query rate per second, not per window.
> It seems to me, that especially the default response-per-second
> rate-limit of 5 is quite low or in other words very strict and it
> potentially rate-limits clients which do not cause any problems.
Yes. The documentation suggests 10 is reasonable.
> In my experience it will already rate-limit monitoring clients.
Shouldn't they be using a recursive server, rather than querying the
My server routinely sin-bins our Nessus scanner which I think is perfectly
fair given the kind of junk Nessus throws at it.
f.anthony.n.finch <dot at dotat.at> http://dotat.at/
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