> On Dec 3, 2014, at 10:45 AM, Stephen Satchell <[email protected]> wrote: > > No. When I've been victim of DNS amplification attacks, the packet > capture showed that the attacker used ANY queries. Legit ANY queries on > my recursive servers? Damn few. So I block. Not so on my > authoritative servers, where ANY queries on the domains I host zone > files for have not caused any problems, for anyone. > > Another thing I did was slow down the port for my recursive DNS servers > to 10 megabits/s. That means that my upstream link can't be saturated > by DNS amplification. Oh, and I rate-limit incoming queries to my DNS > servers by IP address range -- an attack from one subnet won't affect > queries from other parts of the net. Queries from my IP address range > have a high cap; J random IP addresses have a lower cap.
You should not filter the any queries, perhaps you want to TC=1 them. I created a patch for bind for this purpose. http://puck.nether.net/~jared/bind-9.9.3rc2-tcp-any.patch I’ve seen many of these attacks, they will use MX/TXT/A and other records. You may want to look at some of the public resources for this, e.g.: http://dnsamplificationattacks.blogspot.nl/ is a good one and for the git lovers: https://github.com/smurfmonitor/dns-iptables-rules/blob/master/domain-blacklist.txt or https://github.com/smurfmonitor/dns-iptables-rules/blob/master/domain-blacklist-string.txt - Jared
