filtering nslookup results
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Thread: filtering nslookup results

  1. #1
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    Jul 2001
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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

    It\'s a long life, until you die

  2. #2
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    Jul 2002
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    39
    u can filter (deny) port 53 (TCP & UDP) on the NAT rules.

    ByE!
    grobyccil

  3. #3
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    Join Date
    Jul 2001
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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
    dAggressor

    It\'s a long life, until you die

  4. #4
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    Join Date
    Jul 2002
    Posts
    39
    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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