Limit DNS queries

nhaunold · 07-09-2007, 01:29 AM

Hi

I was wondering if it is possible to limit the number of DNS requests a Redhat server can make, per second.
We have had a number of occurrences were a redhat server (actually the Oracle software on that server) floods the network with DNS requests (about 400 a second). Each response is coming back successfull so there is nothing wrong with DNS.
It would be nice to be able to limit a host, to say 50 DNS queries a second.

Thanks
Nick

acid_kewpie · 07-09-2007, 02:18 AM

well that's going to presumably be somethign on the client machine itself, using the iptables limit module...

iptables -A INPUT -p udp -port 53 -m limit --limit 20/s -o eth0 -j ACCEPT

never used this myself, but i *think* this entry will only permit 20 udp/53 packets per second, so drop 380 of them on the client itself.