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Am 28.03.2013 16:38, schrieb Michael Mol: |
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> On 03/28/2013 04:51 AM, Norman Rieß wrote: |
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>> Hello, |
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>> |
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>> i am using pdns recursor to provide a dns server which should be usable |
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>> for everybody.The problem is, that the server seems to be used in dns |
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>> amplification attacks. |
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>> I googled around on how to prevent this but did not really find |
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>> something usefull. |
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>> |
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>> Does anyone got an idea about this? |
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> |
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> I'm not sure it can be done. You can't make a resolver available to |
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> "everybody" without somebody in that "everybody" group abusing it, and |
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> that's exacly what happens in a DNS amplification attack. |
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> |
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> Restrict your resolver to be accessible only to your network or, at |
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> most, those of the specific group of people you're seeking to help. |
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> |
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> You *might* try restricting the resolver to only respond to TCP requests |
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> rather than UDP requests, but if the resolver sends response data along |
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> with that first SYN+ACK, then nothing is solved, and you've opened |
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> yourself up to a SYN flood-based DoS attack. (OTOH, if your resolver |
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> went offline as a result of a SYN flood, at least it wouldn't be part of |
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> an amplification attack any longer...) |
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> |
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Thank you Michael! |
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