Developer Forum

by **Kebba Foo** » Thu, 28 Oct 2010 03:26:36

Dear List,

Is is possible to limit the number of recursion/queries per IP address.
there is some kind of virus thats bombarding my dns servers with a lot
of queries, i realize that when ever the total number of recursion
clients reach 1000 dns resolution stop working. i have increase the
recursive-clients to 10000 but still these those not help. and also i
have increase the number of max open files on my OS which at one point
was complaining about too many open files. can someone please direct me
to how best to solve this problem its some kind of DDOS.

Thanks
Kebba

by **Todd Snyde** » Thu, 28 Oct 2010 04:22:57

What version of bind, on what OS?

There may be some things you can do with iptables to limit connections

http://www.yqcomputer.com/

I don't recall seeing anything native to BIND that would allow for limits per src.

t.

-----Original Message-----
From: bind-users-bounces+tsnyder= XXXX@XXXXX.COM [mailto:bind-users-bounces+tsnyder= XXXX@XXXXX.COM ] On Behalf Of Kebba Foon
Sent: Tuesday, October 26, 2010 2:27 PM
To: XXXX@XXXXX.COM
Subject: limiting number of recursion/queries per IP address

Dear List,

Is is possible to limit the number of recursion/queries per IP address.
there is some kind of virus thats bombarding my dns servers with a lot
of queries, i realize that when ever the total number of recursion
clients reach 1000 dns resolution stop working. i have increase the
recursive-clients to 10000 but still these those not help. and also i
have increase the number of max open files on my OS which at one point
was complaining about too many open files. can someone please direct me
to how best to solve this problem its some kind of DDOS.

Thanks
Kebba

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by **Kebba Foo** » Thu, 28 Oct 2010 04:29:27

I use Debian 5.0 with bind 9.6-ESV-R1 but also i thought that the OS
might have some security holes so i try FreeBSD 8.1 with BIND 9.7.1 but
still have ihave the same problems.

i will just look into these but it done thing iptables will be the ideal
solution.

by **Lightner,** » Thu, 28 Oct 2010 04:36:08

ptables is available in most Linux distros and it is definitely better
to block things there than in BIND itself.

I don't know that BIND has a rate limiter. It DOES have a "blacklist"
option where you can completely block a site's access to it but as noted
above it is better to do it in iptables or firewall because then it
never gets to BIND in the first place.

-----Original Message-----
From: bind-users-bounces+jlightner= XXXX@XXXXX.COM
[mailto:bind-users-bounces+jlightner= XXXX@XXXXX.COM ] On Behalf
Of Kebba Foon
Sent: Tuesday, October 26, 2010 3:29 PM
To: XXXX@XXXXX.COM
Subject: RE: limiting number of recursion/queries per IP address

On Tue, 2010-10-26 at 15:22 -0400, Todd Snyder wrote:
I use Debian 5.0 with bind 9.6-ESV-R1 but also i thought that the OS
might have some security holes so i try FreeBSD 8.1 with BIND 9.7.1 but
still have ihave the same problems.

i will just look into these but it done thing iptables will be the ideal
solution.
limits per src.
[mailto:bind-users-bounces+tsnyder= XXXX@XXXXX.COM ] On Behalf Of
Kebba Foon
address.
me
information, privileged material (including material protected by the
solicitor-client or other applicable privileges), or constitute
non-public information. Any use of this information by anyone other than
the intended recipient is prohibited. If you have received this
transmission in error, please immediately reply to the sender and delete
this information from your system. Use, dissemination, distribution, or
reproduction of this transmission by unintended recipients is not
authorized and may be unlawful.

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by **Sebastian** » Fri, 29 Oct 2010 04:26:57

n FreeBSD you can use pf to limit connections using tables and setting up
rate limit.

http://forums.freebsd.org/showthread.php?t=1727

Best regards,

Shamrock

On Tue, Oct 26, 2010 at 9:29 PM, Kebba Foon < XXXX@XXXXX.COM > wrote:

In FreeBSD you can use pf to limit connections using tables and setting up rate limit.<br><br><a href="http://forums.freebsd.org/showthread.php?t=1727">http://forums.freebsd.org/showthread.php?t=1727</a><br><br>Best regards,<br>
<br>Shamrock<br><br><div class="gmail_quote">On Tue, Oct 26, 2010 at 9:29 PM, Kebba Foon <span dir="ltr"><<a href="mailto: XXXX@XXXXX.COM "> XXXX@XXXXX.COM </a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im">On Tue, 2010-10-26 at 15:22 -0400, Todd Snyder wrote:<br>
</div>I use Debian 5.0 with bind 9.6-ESV-R1 but also i thought that the OS<br>
might have some security holes so i try FreeBSD 8.1 with BIND 9.7.1 but<br>
still have ihave the same problems.<br>
<div class="im"><br>
</div>i will just look into these but it done thing iptables will be the ideal<br>
solution.<br>
<div><div></div><div class="h5">> I don't recall seeing anything native to BIND that would allow for limits per src.<br>

<br>
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<a href="mailto: XXXX@XXXXX.COM "> XXXX@XXXXX.COM </a><br>
<a href="https://lists.isc.org/mailman/listinfo/bind-users" target="_blank">https://lists.isc.org/mailman/listinfo/bind-users</a><br>
</div></div></blockquote></div><br>

by **Dmitry Ryb** » Wed, 10 Nov 2010 23:22:58

his is not good idea to use statefull firewall on heavy loaded DNS
server. firewall becomes low place in the system.

As workaround you can use dns_flood_detector + simple script to insert
and remove IP's from firewall blocking table or chain.

27.10.2010 23:26, Sebastian Tymkw :

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