RE:Reflexive firewalls?

[securitylists () uniontown com]

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.