Prevent Stealth Scans

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Apr 2nd, 2007
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What is the best defense against stealth scans of the network? I know this is a vague and open question.

How do you prevent when signature detects a single TCP packet with none of the control bits, i.e. SYN, FIN, ACK, PSH, URG or RST flags set being sent to a specific host.

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David White Mon, 04/02/2007 - 08:55
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I'm not sure we are totally following your question. Are you asking specificly to the PIX/ASA/FWSM or a more generic question relating to IPS/IDS?



mhellman Mon, 04/02/2007 - 09:12
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The Pix will drop null packets. Any firewall should.

David White Mon, 04/02/2007 - 09:12
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The PIX will silently drop these packets (ie: no syslog generated). In 7.x, many of these will get counted in the "show asp drop" output, but again, no syslog generated.



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