Re: Reflexive firewalls?

Hi,

My suggestion is google://iptables+recent+example

This is not perfect, it might not even be working, but your solution with nf 
would probably look something like this:

$IPTABLES -A INPUT -p TCP --dport 1234 \
-m recent --name knock --set -j ACCEPT

$IPTABLES -A INPUT -p TCP --dport 22 -m recent \
--name knock --rcheck --seconds 120 --hitcount 1 -j ACCEPT

Cheers,
0x90

----- Original Message ----- 
From: "Danilo Chilene" <dchilene@impsat.com>
To: "Ong Chin Kiat" <ong.chinkiat@gmail.com>
Cc: <security-basics@securityfocus.com>
Sent: Thursday, December 27, 2007 7:02 PM
Subject: Re: Reflexive firewalls?


> I know how do this with PF.
>
> Don't have any idea with iptables. :(
>
> 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.
>
> --
> Danilo F. Chilene
>
> Especialista SO
>
> Global Crossing Limited
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>
>
> Att,