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Thread: filtering nslookup results

  1. March 22nd, 2003, 12:57 AM #1
    dAggressor
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    filtering nslookup results

    Does anyone have an idea on how to filter nslookup results from inside a firewall when trying to use an outside dns server as the source? Basically if I have a RedHat 7.2 server running iptables and acting as a NAT server, how could I make it not allow "inside" users to use nslookup or dig without our DNS being the source server?

    Thanks for any help or assistance you can lend.
    dAggressor

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  2. March 23rd, 2003, 09:42 PM #2
    grobyccil
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    u can filter (deny) port 53 (TCP & UDP) on the NAT rules.

    ByE!
    grobyccil
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  3. March 24th, 2003, 12:24 AM #3
    dAggressor
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    That's true, but I guess I would have to only allow 53 to our specific dns IP address. I will give that a shot, that was the direction I was leaning anyway, I just wanted to know if there was a better method. Thanks for your help.

    dAggressor
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  4. March 25th, 2003, 03:17 PM #4
    grobyccil
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    When u have a NAT, the requests comes to the firewall, are translated and the fw send the packets to destination.
    If u have a dns server, then the internal PC can resolve the names using it. In other case, they needs send the dns queries to another dns server.
    External machines dont know if you have a 'real' PC (real IP) or internal PC. They just see the real IP.

    ByE!
    groby

    PS Sorry for my english...
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