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Date:      Fri, 17 Jan 1997 17:00:49 +1100 (EDT)
From:      Darren Reed <avalon@coombs.anu.edu.au>
To:        phk@critter.dk.tfs.com (Poul-Henning Kamp)
Cc:        hackers@freebsd.org
Subject:   Re: ipfw patches to test
Message-ID:  <199701170600.WAA12795@freefall.freebsd.org>
In-Reply-To: <2879.853470405@critter.dk.tfs.com> from "Poul-Henning Kamp" at Jan 17, 97 04:06:45 am

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In some mail from Poul-Henning Kamp, sie said:
> 
> In message <199701170143.RAA01789@freefall.freebsd.org>, Darren Reed writes:
> >> > > 
> >> > > Basically you can now say
> >> > > 
> >> > > 	ipfw add deny !from 192.168.23.0/30 to 140.145.230.0/24
> >> > > 
> >> 
> >> What's the difference between the above and
> >> 
> >> ipfw add allow from 192.168.23.0/30 to 140.145.230.0/24
> >> ipfw add deny from any to 140.145.230.0/24
> >
> 
> In the top case I can go on filter on the 192.168 -> 140.145 traffic,
> in the bottom case it has all been allowed.

You can filter on 192.168 -> 140.145, but you have to be more careful about
how it is done, typically, you need the order to be most specific to most
general.

IP Filter handles this better;

pass in from 192.168.23.0/32 to 140.145.230.0/24
block in from any to 140.145.230.0/24

- neither rule terminates the searching for more "matching" rules later
in the list.  You could describe this by saying the "pass" sets up a
template which can be refined.

Darren



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