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Date:      Sun, 4 Feb 2001 10:59:29 -0500 (EST)
From:      Robert Watson <rwatson@freebsd.org>
To:        Rich Wales <richw@webcom.com>
Cc:        freebsd-net@freebsd.org, freebsd-stable@freebsd.org
Subject:   Re: BRIDGE breaks ARP? (more info)
Message-ID:  <Pine.NEB.3.96L.1010204105615.65610B-100000@fledge.watson.org>
In-Reply-To: <20010204062837.94849.richw@wyattearp.stanford.edu>

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On Sat, 3 Feb 2001, Rich Wales wrote:

> Earlier, I reported an ARP problem on a 4.2-STABLE bridge system. 
> 
> A few people wrote me privately, advising me to include a firewall rule
> passing UDP packets on port 2054 to/from the IP address 0.0.0.0. 
> 
> I've tried this, but it doesn't help any.  I should mention, though,
> that I don't think this firewall rule is relevant in any case. 
> 
> First, the "port 2054" kludge doesn't appear to be in the networking
> code any more.  I grep'ed the entire -STABLE base source for any
> references to UDP port 2054, and I found nothing at all except for the
> commented-out line in the etc/rc.firewall file.  As far as I'm aware,
> bridging of non-IP packets is now controlled by the kernel's default
> "ipfw" rule -- and, yes, I do have the options IPFIREWALL and
> IPFIREWALL_DEFAULT_TO_ACCEPT in my configuration. 

There used to be a kludge that mapped the ether_header.ether_type field of
non-IP packets into the UDP port number for the purposes of certain IPFW
rules when bridging.  This was pretty awful.  :-)  That kludge was
removed, and the BRIDGE code now simply forwards all non-IP packets,
including ARP, and does not pass them through IPFW when IPFW is enabled,
making them follow the equivilent of a default pass rule.  This is a
kludge that I am glad to see go: I can certainly imagine the desire to
support non-IP filtering in a bridge, but IPFW was not the right vehicle
for that.  I believe the removal of the kludge occurred along with
Archie's other fixups around Jun 21, 2000, which was certainly prior to
4.2-RELEASE.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Project
robert@fledge.watson.org      NAI Labs, Safeport Network Services



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