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Alexander Schreiber wrote: |
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> On Thu, Jan 08, 2004 at 06:57:28PM +0100, Daniel Privratsky wrote: |
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> |
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>>Wrong. |
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>> |
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>>1) If you don't receive "destination unreachable" packet, you know |
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>>nothing about the target host yet. This is not perfect-network world. |
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>>There can be other fw/router anywhere in the way, killing this type of |
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>>icmp traffic. |
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>> |
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>>2) It slows scans a lot. |
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> |
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> |
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> Only for people too stupid for doing port scans (a rare defect even |
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> among script kiddies). |
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|
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Hmmm, a little schisophrenic situation. Are we talking about mass scan |
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seeking for live systems in some IP space or directed attack to your |
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specific system? |
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For the first scenario it is some useful protection. No response still |
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means system down, attacker will hardly waste time for detail investigation. |
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For the second scenario, it's useful too. Time out waiting will slow him |
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down. |
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|
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> |
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> |
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>>You can of course do scannig in parallel, but |
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>>don't be surprised, when you find yourself killed with no mercy by IDS, |
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>>after matching SYN threshold. 1000+ syns/sec form IP adress to monitored |
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>>system is sure ban. |
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> |
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> |
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> Cool. Your IDS just banned the IPs of your customers mail-, web- and |
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> proxy-servers. Spoofing IP adresses just to mess with such automatic |
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> systems is easy. |
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Nonsense. Such active-response IDS is primary site protection. It |
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detects incoming SYNs, not outgoing. |
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|
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Regards |
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|
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Dan |
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> |
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> Regards, |
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> Alex. |
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-- |
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