Re: Port-Knocking vulnerabilities?

["T. Shannon Gilvary" <tsgilvary () enconmech com>]

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.
(732)922-1305
Fax: (732)922-0745
tsgilvary () enconmech com