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Re: Tightened DNS security question re: DNS amplification attacks.
From: jay () miscreant org
Date: Wed, 28 Jan 2009 08:42:39 +1100

Quoting Matthew Huff <mhuff () ox com>:

Given the recent DNS amplification attacks, I've audit and updated our
authoritative servers. We are using 9.6.0-P1 now. I've been using the cyrmu
templates, but one thing I see is that the dns queries to the . hint file
are still occuring and are not being denied by our servers. For example:

27-Jan-2009 15:00:22.963 queries: client 64.57.246.146#64176: view
external-in: query: . IN NS +
27-Jan-2009 15:00:23.118 queries: client 64.57.246.146#33146: view
external-in: query: . IN NS +

the named.conf has:

...
...
...

view "external-in" in {
  match-clients { any; };
  recursion no;
  additional-from-auth no;
  additional-from-cache no;

  zone "." in {
    type hint;
    file "db.cache";
  };
...
...

since you can't put a "allow-query { none; };" in a hint zone, what can I do
to deny the query to the . zone file?



----
Matthew Huff       | One Manhattanville Rd
OTA Management LLC | Purchase, NY 10577
http://www.ox.com  | Phone: 914-460-4039
aim: matthewbhuff  | Fax:   914-460-4139


Hi Matthew,

I'm using the following with 9.5.1:

view    "external" {
    recursion no;
    allow-query-cache { none; };
    zone "." IN {
        type hint;
        file "/var/named/named.ca";

And my logs indicate that the requests for . IN NS are being denied:

Jan 28 08:40:38 web1 named[12337]: client 64.57.246.146#33453: view external: query (cache) './NS/IN' denied Jan 28 08:40:39 web1 named[12337]: client 67.192.144.0#41794: view external: query (cache) './NS/IN' denied

Cheers,

Jay



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