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Date:      Mon, 26 Feb 1996 12:37:51 -0600 (CST)
From:      Joe Greco <jgreco@brasil.moneng.mei.com>
To:        tom@uniserve.com (Tom Samplonius)
Cc:        imb@scgt.oz.au, phk@critter.tfs.com, stable@FreeBSD.ORG, current@FreeBSD.ORG
Subject:   Re: -stable hangs at boot (fwd)
Message-ID:  <199602261837.MAA15680@brasil.moneng.mei.com>
In-Reply-To: <Pine.BSF.3.91.960226091641.21606B-100000@haven.uniserve.com> from "Tom Samplonius" at Feb 26, 96 09:17:59 am

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> On Tue, 27 Feb 1996, michael butler wrote:
> 
> > Poul-Henning Kamp writes:
> > 
> > > Well, this happens to be your view.  I know machines where IPFW are being
> > > used to restrict what users on the machine can do, this is only possible
> > > if you filter >ALL< traffic, to and from the machine.
> > 
> > I haven't checked this but .. what happens to a packet which matches a
> > "reject" rule when it's not actually destined for the machine doing the
> > filtering .. does it still generate an ICMP "host unreachable" ?
> 
>   The system shouldn't be getting packets not destined for it, unless the 
> interface is in promiscous mode, which it not normally.

Think about: 
"route add -net 123.45.67.0 -netmask 0xffffff00 some.firewall.router.org 1"

Not all packet delivery(/routing) is passively sitting on your butt on an
Ethernet waiting for an ARP request.  Sometimes you have things pushed
at you by other routers  :-)

In my opinion it would be most useful to catch things and return ICMP
HOST_UNREACHABLE messages at the firewall.  Your average Cisco/etc router
can do it.  The only thing you might need to be careful about would be
broadcasts/multicasts.

... Joe

-------------------------------------------------------------------------------
Joe Greco - Systems Administrator			      jgreco@ns.sol.net
Solaria Public Access UNIX - Milwaukee, WI			   414/546-7968



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