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RE:Reflexive firewalls?

Subject: RE:Reflexive firewalls?
Date: Thu, 27 Dec 2007 13:35:05 -0500 (EST)
What you are describing sounds like "port knocking".  Sorry, no links, but 
Google will certainly help you if you use that phrase.

Mark Coleman



Ong Chin Kiat wrote ..
Hi list,

I've recently used an SSH server that had an interesting authentication 
mechanism. You first had to telnet to the machine on a certain port. 
After doing this (it will just time out - no prompt), you then SSH to 
the server in question. The telnet step has to be carried out, if not 
SSH will just time out.

My question is, is this called reflexive firewalling, and can I 
duplicate this with iptables?

Thanks.
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