DNS Blocking

Thu Aug 19 18:25:19 UTC 2004

Hey guys,

I was recently hammered by someone making a ton of requests for a 
non-existent subdomain of a domain that I host.  The requests were coming 
in from forged ips, and presumably being used to flood other people.

Because DNS is udp based, and the sender of the queries honestly didn't 
care about getting a response back, traditional firewalls were useless.  I 
imagine a sniffing firewall that can look at the packet payloads would 
have been more useful, but I was wondering if anyone knew a way to better 
mitigate this type of attack.

I posted on comp.protocols.dns.bind, didn't get back anything of use.  I 
posted on webhostingtalk, and got a pointer at the "securing bind" paper 
(which neither addresses the situation, nor includes anything to prevent 
it).

What I was basically asking for was a "silently drop queries for X-domain" 
option.  But one doesn't exist in bind.

I know it's a little off-topic, but I'd appreciate any pointers.

-Dan Mahoney

--

"...Somebody fed you sugar.  Shit!"

--Tracy, after noticing Gatorade on my desk.

Ezzi Computers, October 18th 2003
Approx 11PM

--------Dan Mahoney--------
Techie,  Sysadmin,  WebGeek
Gushi on efnet/undernet IRC
ICQ: 13735144   AIM: LarpGM
Site:  http://www.gushi.org
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