From doug@lafn.org  Sun Oct 14 06:36:25 2012
Return-Path: <doug@lafn.org>
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id C06F94E9
	for <FreeBSD-gnats-submit@freebsd.org>; Sun, 14 Oct 2012 06:36:25 +0000 (UTC)
	(envelope-from doug@lafn.org)
Received: from zoon.lafn.org (zoon.lafn.org [108.92.93.122])
	by mx1.freebsd.org (Postfix) with ESMTP id 93EF08FC08
	for <FreeBSD-gnats-submit@freebsd.org>; Sun, 14 Oct 2012 06:36:25 +0000 (UTC)
Received: from zoon.lafn.org (localhost [127.0.0.1])
	by zoon.lafn.org (8.14.3/8.11.3) with ESMTP id q9E6WTHA035386
	for <FreeBSD-gnats-submit@freebsd.org>; Sat, 13 Oct 2012 23:32:29 -0700 (PDT)
	(envelope-from doug@zoon.lafn.org)
Received: (from doug@localhost)
	by zoon.lafn.org (8.14.3/8.13.8/Submit) id q9E6WT3G035384
	for FreeBSD-gnats-submit@freebsd.org; Sat, 13 Oct 2012 23:32:29 -0700 (PDT)
	(envelope-from doug)
Message-Id: <201210140632.q9E6WT3G035384@zoon.lafn.org>
Date: Sat, 13 Oct 2012 23:32:29 -0700 (PDT)
From: Doug Hardie <doug@lafn.org>
To: FreeBSD-gnats-submit@freebsd.org
Subject: Duplicate IPv6 Link Local Addresses

>Number:         172683
>Category:       kern
>Synopsis:       [ip6] Duplicate IPv6 Link Local Addresses
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-net
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Oct 14 06:40:00 UTC 2012
>Closed-Date:    
>Last-Modified:  Sat Nov  2 22:40:01 UTC 2013
>Originator:     Doug Hardie <bc979@lafn.org>
>Release:        FreeBSD 9.1-RC2 i386
>Organization:
>Environment:
System: FreeBSD master.lafn.org 9.1-RC2 FreeBSD 9.1-RC2 #0 r241133: Tue Oct 2 17:11:45 UTC 2012 root@obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC i386


>Description:
	You can assign identical link local addresses to two different 9.1-RC2
	systems on the same LAN and the problem is not detected.  When the 
	second machine becomes alive it properly sends a Neighbor Solication
	with the proper address, but the first machine does not respond to it
	with a Neighbor Advertisement which would alert the second machine to
	the duplication and permit it to select a different address.  As a
	result both machines have the same link local address and nothing works.

>How-To-Repeat:
	Determine the link local address the second machine will use and shut it	down.  On the first machine assign manually that link local address to
	the appropriate port.  Run a tcpdump -ixxx -vx ip6 on the first machine
	and power up the second.  The second machine will send a Neighbor 
	Solication with the duplicated address, but the first machine will not
	respond to that packet.

	I have one machine that never sends the original Neighbor Solication 
	for the link local address.  It does send for its global addresses.  
	It just starts using the link local address.  I can't find any
	significant differences between those two systems other that the
	first was a direct install from the CD and the second was a
	freebsd-update from 9.1-RC1.
>Fix:

	


>Release-Note:
>Audit-Trail:
Responsible-Changed-From-To: freebsd-bugs->freebsd-net 
Responsible-Changed-By: linimon 
Responsible-Changed-When: Sun Oct 14 16:44:21 UTC 2012 
Responsible-Changed-Why:  
Over to maintainer(s). 

http://www.freebsd.org/cgi/query-pr.cgi?pr=172683 

From: Doug Hardie <bc979@lafn.org>
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: kern/172683: [ip6] Duplicate IPv6 Link Local Addresses
Date: Sun, 14 Oct 2012 16:42:50 -0700

 Here is some more interesting information on the issue.  RFC 4862 states =
 that if the link-local address is MAC based then it should bring down =
 the link and log the duplicate address error.  Kurt Jaeger pointed out =
 in a private email that there is a sysctl that is supposed to control =
 this behavior: net.inet6.ip6.dad_count.  The value 1 is to permit the =
 interface to continue to operate and the value 2 is to stop operation.  =
 Sure enough net.inet6.ip6.dad_count =3D 1 as the default value.  I =
 changed it to 2 and ran the tests again.  There was no change in the =
 performance.  The interface remained in use and nothing was logged in =
 /var/log/messages.  Unfortunately I no longer have a Vista machine to =
 test with since it generates non-MAC related link-local addresses.  XP =
 and Win 7 both use MAC based addresses.  Using Vista talking to FreeBSD =
 7.2, the Neighbor Advertisement was returned by FreeBSD and Vista chose =
 another link-local address.=

From: Mohamad Aghakhani <www.mohamad607@gmail.com>
To: bug-followup@FreeBSD.org, doug@lafn.org
Cc:  
Subject: Re: kern/172683: [ip6] Duplicate IPv6 Link Local Addresses
Date: Sun, 3 Nov 2013 02:02:34 +0330

 --089e0139ffb864788604ea394257
 Content-Type: text/plain; charset=ISO-8859-1
 
 
 
 --089e0139ffb864788604ea394257
 Content-Type: text/html; charset=ISO-8859-1
 
 
 
 --089e0139ffb864788604ea394257--
>Unformatted:
