Comcast residential DNS contact
Jared Mauch
jared at puck.nether.net
Wed Dec 3 17:58:20 UTC 2014
> On Dec 3, 2014, at 10:45 AM, Stephen Satchell <list at satchell.net> 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
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