[dns-operations] solutions for DDoS mitigation of DNS
klaus.mailinglists at pernau.at
Thu Apr 2 11:09:17 UTC 2020
Am 02.04.2020 um 09:15 schrieb Frank Louwers:
> dnsdist allows you to do general ratelimiting/blocking
Ratelimiting is often not the correct choice.
If the source IP is random (which is usually the case with spoofed
source IP addresses), a rate limiting based on source IP is not useful.
If the query-name is random (which is usually the case with spoofed
source IP addresses), a rate limiting based on qname is not useful.
If the qname is always the same, or at least within the same zone, you
could do rate limiting for that zone, but this limits all queries,
attack queries and legitim queries. Hence, you create a DoS for that
zone, but at least avoid collateral damage to other zones hosted on that
So my advice: use a name server which can fill your upstream bandwith
(NSD, Knot ...). And for volumetric attacks use a commercial DDoS
mitigation provider which filters your traffic (ie. buy the service from
your ISP or from a remote DDoS mitigation provider which announces your
prefixes on demand.)
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