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Recursive DNS on Domain controller that has port 53 exposed externally

Posted on 2012-08-22
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Last Modified: 2012-10-05
Hello,

At my department within the University, I have two 2008R2 domain controllers.  Originally they were not exposed to the world; however in the past few months, port 53 was opened so that our external teams could access certain internal machines.  

The university did a network scan and said that my DC was a recursive DNS server, which could possibly lead to denial of service attacks.  

I looked yesterday and an article said to set "secure only" on all of my forward and reverse lookup zones as well as disable recursive DNS.  I click on the disable recursive DNS and things stopped working.  I unchecked it and things, of course, started working.  Since I do not use any forwarders, I rely on root hints.  Disabling recursive DNS disables that as well.

What exactly can/should I do to ensure I have the correct securing on this server so that my DNS does not get owned.

Thanks,
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Question by:lbtoadmin
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Accepted Solution

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Mike Kline earned 2000 total points
ID: 38321699
You are sort of stuck in your situation because you don't have forwarders and are relying on root hints.  

You could forward "all other domains" to something like the Google DNS servers  
https://developers.google.com/speed/public-dns/

You could then check the "do not user recursion for this domain"...note in 2008 DNS the wording good screenshots here

http://www.itgeared.com/articles/1050-do-not-use-recursion-for-this-domain-vs/



By the say if anyone wants to know more about issues from a security standpoint see

http://www.readwriteweb.com/enterprise/2012/03/ed-skoudis-of-sans-on-the-vuln.php

Thanks

Mike
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Author Closing Comment

by:lbtoadmin
ID: 38467701
We've decided to close the port because our VPN will be the solution for this.  Much more secure.  The solution Mike provided did answer my question and provided me with good security insight.
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