From owner-freebsd-hackers  Fri Dec 29 08:00:49 1995
Return-Path: owner-hackers
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id IAA27625
          for hackers-outgoing; Fri, 29 Dec 1995 08:00:49 -0800 (PST)
Received: from brasil.moneng.mei.com (brasil.moneng.mei.com [151.186.109.160])
          by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id IAA27620
          for <freebsd-hackers@freebsd.org>; Fri, 29 Dec 1995 08:00:45 -0800 (PST)
Received: (from jgreco@localhost) by brasil.moneng.mei.com (8.7.Beta.1/8.7.Beta.1) id JAA08145; Fri, 29 Dec 1995 09:59:41 -0600
From: Joe Greco <jgreco@brasil.moneng.mei.com>
Message-Id: <199512291559.JAA08145@brasil.moneng.mei.com>
Subject: Re: bug in UDP stack with our aliasing scheme :-(
To: guido@IAEhv.nl (Guido van Rooij)
Date: Fri, 29 Dec 1995 09:59:40 -0600 (CST)
Cc: freebsd-hackers@freebsd.org
In-Reply-To: <199512291149.MAA13378@iaehv.IAEhv.nl> from "Guido van Rooij" at Dec 29, 95 12:49:46 pm
X-Mailer: ELM [version 2.4 PL24]
Content-Type: text
Sender: owner-hackers@freebsd.org
Precedence: bulk

> I discovered a problem with our ip aliasing implementation:
> 
> Suppose you have an interface, ed0, with ip 192.1.1.1 netmask 0xffffff00.
> Further there is an alias 192.1.1.2, with netmask 0xffffffff.
> 
> Run the program attached below with argument 192.1.1.1. Send an UDP
> packet to 192.1.1.1. The program will only receive the data on fd1.
> When the program is run with argument 192.1.1.2 it receives input
> both on fd1 and fd2.
> 
> When the alias is set to an ip on another subnet, say 192.1.2.1 with
> netmask 0xffffffff, this bug can be seen again. But when the netmask is
> changed to 0xffffff00, the UDP data will be deliverd correctly to only
> fd1.

This (other than that last bit) is consistent with a BIND (named) server
problem that I've been tracking for a while.  I would be happy to test any
suggested fixes  :-)

... JG