Re: Open DNS Resolver reflection attack Mitigation

[Owen DeLong <owen () delong com>]

On Jun 8, 2012, at 12:26 PM, Stephane Bortzmeyer wrote:

> On Fri, Jun 08, 2012 at 03:09:04PM -0400,
> Joe Maimon <jmaimon () ttec com> wrote 
> a message of 7 lines which said:
>
> > Is there any publicly available rate limiting for BIND?
>
> Not as far as I know. I'm not sure it would be a good idea. BIND is
> feature-rich enough.
>
> > How about host-based IDS that can be used to trigger rtbh or iptables?
>
> What I do (I manage a small and experimental open resolver) is to use
> iptables this way (porting it to IPv6 is left as an exercice):
>
> iptables -A INPUT -p udp --dport 53 -m hashlimit \
>   --hashlimit-name DNS --hashlimit-above 20/second --hashlimit-mode srcip \
>   --hashlimit-burst 100 --hashlimit-srcmask 28 -j DROP

IPv6 should be a simple matter of putting the same line in your ip6tables file.

Owen