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Re: IP Chains question



Rick Macdonald wrote:

On Thu, 31 Jan 2002, Eric G. Miller wrote:


On Thu, 31 Jan 2002 09:08:45 -0500 (EST), Matt Kopishke <kopishke@BlueNoteTechnology.com> wrote:


I have set up a firewall using ipchains and the bridge patch
(bridgein) under potato (2.2.19).  The one snag I had was although the
firewall works well only letting the world see certain ports (80 & 443),
it doesn't let the servers behind the firewall get out.  I set up a rule
that allows all traffic that originated behind the firewall out, but
because we only have a couple of ports open, and we have no clue what port
the reply packets are going to come on, the reply packets get denied.

I was wondering if there is any way to mark out going packets so we can
let them through on their way back?

Yea, it's called iptables/netfilter (kernel 2.4.x).


I've just switched to 2.4.x on my laptop, and it was painless. I'm about
to do the same on a desktop that runs a firewall using my old original
ipfwadm rules, which are magically translated by debian (potato/2.2.x) into (i think) ipchains.

Is there someplace I can find instructions to convert to iptables? Is
there a similar on-the-fly conversion script?

...RickM...


If you intend to switch to iptables from ipchains,
I strongly suggest you to take a look at http://netfilter.samba.org/

The thing you are looking for is something called
connection tracking. There is loads of stuff on
google. Of course you will have to some extent
modify the rules manually to add connection tracking functionality.
It's quite simple once you get the hang of it.

David.



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