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To: Jeremy Chadwick <koitsu@FreeBSD.org>
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	<490A4487.8020101@gmail.com> <20081030233933.GB16747@icarus.home.lan>
From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>
Date: Fri, 31 Oct 2008 12:05:28 -0400
In-Reply-To: <20081030233933.GB16747@icarus.home.lan> (Jeremy Chadwick's
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Cc: Jack Barnett <jackbarnett@gmail.com>,
	Freebsd questions <freebsd-questions@freebsd.org>, mdh_lists@yahoo.com
Subject: Re: Firewalls in FreeBSD?
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Jeremy Chadwick <koitsu@FreeBSD.org> writes:

> On Thu, Oct 30, 2008 at 06:34:31PM -0500, Jack Barnett wrote:
>>
>> Ok, I had some progress with this last night. Basically what I do is:
>>
>> in natd - redirect_port 1000 to 10000 to the internal windows box.
>> set ipfw to "open" file wall.
>>
>> Obviously this isn't prefect - but gives some idea of what's going on.
>>
>> What I'd like to do, is a) keep the nat redirects since that works  
>> pretty well.
>> b) in ipfw, ONLY allow data back on these ports IF the windows box has  
>> established the connection out first then deny everything else.
>
> This is called "port triggering" in the residential router world.  I
> don't know how to do this on FreeBSD.

Stateful rules are the only way to do it.
In fact, this is the main purpose of stateful rules.

-- 
Lowell Gilbert, embedded/networking software engineer, Boston area
		http://be-well.ilk.org/~lowell/