Date: Mon, 21 Aug 2000 18:18:25 -0400 From: Bill Fumerola <billf@chimesnet.com> To: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> Cc: William Wong <willwong@anime.ca>, freebsd-security@FreeBSD.ORG Subject: Re: icmptypes Message-ID: <20000821181825.I57333@jade.chc-chimes.com> In-Reply-To: <200008212216.PAA31247@gndrsh.dnsmgr.net>; from freebsd@gndrsh.dnsmgr.net on Mon, Aug 21, 2000 at 03:16:03PM -0700 References: <20000821180351.H57333@jade.chc-chimes.com> <200008212216.PAA31247@gndrsh.dnsmgr.net>
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On Mon, Aug 21, 2000 at 03:16:03PM -0700, Rodney W. Grimes wrote:
> > example from memory:
> > # ipfw add unreach filter-prohib icmp from any to any icmptypes 0,8
>
> The 8 case would be okay, but returning an icmp unreach for an icmp echo
> reply would be a violation of the protocol spec. I would recomend
> against it.
Yes, unreaching 0 would be nonsense I suppose.
On a side note, RFC and protocol blah blah is nice, but sometimes you
just have to drop packets and break spec if the machine is a target.
If this is being used as a border firewall or some such, then I would
certainly heed Rod's advice on being careful what to break. For a single
machine, I'd be less worried.
--
Bill Fumerola - Network Architect, BOFH / Chimes, Inc.
billf@chimesnet.com / billf@FreeBSD.org
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