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Date:      Wed, 13 Feb 2002 03:22:49 -0700
From:      "John Nielsen" <oniblerz@attbi.com>
To:        <stable@freebsd.org>
Subject:   strange ip alias behavior on -stable
Message-ID:  <0bfc01c1b478$6349a310$0900a8c0@max>

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[some of this may be redundant if my earlier message actually made it to
the list, but I never saw it...]

I recently set up (and still administer) a firewall running FreeBSD
4.5-RELEASE.  The machine has a Tyan Tiger motherboard with 2 onboard
intel (fxp) nics, an onboard promise 100 raid controller, and dual CPU
slots.  There is only one CPU in the machine.

The firewall has aliases for several IP addresses on the external
interface, and redirects specific address:port combinations from the
outside to several machines on an internal network.  I had this all set up
(using ipfw and natd) a few days ago, and it was working fine.

When I noticed the commit of some bugfixes and improvements to the ata
raid code, I decided to try tracking stable on this machine.  I cvsup'ed
the source, did a buildworld, buildkernel, installkernel, installworld,
and ran mergemaster.  The whole process went very smoothly.  Everything
appeared to be working fine, only now the aliases weren't accessible from
outside the local (external) network.  That is, a machine plugged into the
same hub as the external interface of this firewall could get a ping reply
from all of the alias addresses, and natd worked as expected.  However, a
remote machine could only get ping replies from the primary (non-alias) IP
address, and natd wouldn't pass packets on any of the alias addresses
(likely because they never made it to natd at all).

I tried updating the source again a few days later to see if it was a
fluke of some sort, but the no-alias behavior persisted.  In fact, I tried
everything I could think of (including cvsup-ing from the RELENG_4_5
branch and recompiling), but to no avail.  The only thing that worked was
a reinstall (from scratch) of 4.5-RELEASE.

So now I'm wondering why this weird behavior would occur in the first
place.  Is it a bug in -stable?  Is the router at my co-lo quirky? (I
believe it's a cisco.)  Has anyone else experienced this behavior on any
version of FreeBSD?  In a word, WHY?  (This has only been mildly
frustrating for me.  Really. :) )

Now that it's behaving again (running 4.5-R), this server has gone back
into production.  So I don't think I'll be reproducing the error any time
soon even for testing or generating a bug report.  If it is a FreeBSD bug,
though, then I'd certainly love to see it tracked down.  In any case, I'd
appreciate whatever feedback and ideas the list can offer.

Thanks,

John Nielsen


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