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Re: Port-Knocking vulnerabilities?
From: "T. Shannon Gilvary" <tsgilvary () enconmech com>
Date: Fri, 28 Dec 2007 13:38:47 -0500

Kappa Alpha Pi Eta wrote:
Hi listers.

so I read this thread about port-knocking (altough called "reflexsive
firewalls"). I'd never heard of that and found that to be an very
interesting mechanism. Now I just keep wondering, what an attacker
could possibly do to intrude system secured in such a way. So there
are no open ports at all, also, there's no way the attacker could
access the computer physically or via social engineering. The
attacker knows that a knock-server is running and that there's some
daemon waiting to become accessible (what ever that may be). What could a attacker do to somehow get access to that machine? And
how can I secure that machine from that kind of attacks.

If the attacker is aware there is port knocking instituted on the server and can sniff the packets, the port knock essentially becomes a password in the clear. It's useful as an extra layer of security, but far from invulnerable to a determined attacker.

T. Shannon Gilvary
Encon Mechanical, Corp.
Fax: (732)922-0745
tsgilvary () enconmech com

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