Pkg xen devel - May 2012 - Bug#671018: [xen-utils-common] qemu-ifup breaks networking by changing mac address

Package: xen-utils-common
Version: 4.0.0-1
Severity: important
Tags: patch

--- Please enter the report below this line. ---

when you use "hardware" virtual machine (with qemu) with xen
configured for bridging
the network script treates a tap interface and then
/etc/xen/scripts/qemu-ifup adds it to the bridge.

That would be ok but tap interfaces have a random mac address and the
bridge always gets tha lowest mac address.
considered dom0 uses this bridge, this can lead to a loss of network
connection.
The probability of getting this problem changes with the real mac
address of the main interface.
(No chance mine starts with "BC" )

A nice solution is to change the mac address of the tap interface to
some very high and unlikely value before it is added to the bridge.

Here is my version of /etc/xen/scripts/qemu-ifup
It has some logs inside that can be removed but I feel it useful for
checking.


#!/bin/sh

echo -c 'config qemu network with xen bridge for '
echo $*

####MY PATCH
#echo "Current config of $1 "
#ip link show $1
echo "Changing mac address of $1 to fe:ff:ff:ff:ff:ff"
ip link set $1 addr fe:ff:ff:ff:ff:ff
#echo "checking new config of $1 "
#ip link show $1
####END OF MYPATCH

ifconfig $1 0.0.0.0 up
brctl addif $2 $1



--- System information. ---
Architecture: amd64
Kernel: Linux 2.6.32-5-xen-amd64

Debian Release: 6.0.4
500 stable security.debian.org
500 stable ftp.fr.debian.org
500 squeeze-backports mozilla.debian.net
100 squeeze-backports backports.debian.org

--- Package information. ---
Package's Depends field is empty.

Package's Recommends field is empty.

Package's Suggests field is empty.

Your message dated Mon, 30 Jul 2012 21:33:43 +0000
with message-id <E1Svxax-0006Xf-F0 at franck.debian.org>
and subject line Bug#671018: fixed in xen 4.1.3~rc1+hg-20120614.a9c0a89c08f2-5
has caused the Debian Bug report #671018,
regarding [xen-utils-common] qemu-ifup breaks networking by changing mac address
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner at bugs.debian.org
immediately.)


-- 
671018: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=671018
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems
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From: Pierre Colombier <pcdwarf at pcdwarf.net>
Subject: [xen-utils-common] qemu-ifup breaks networking by changing mac address
Date: Tue, 01 May 2012 12:03:42 +0200
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From: Bastian Blank <waldi at debian.org>
Subject: Bug#671018: fixed in xen 4.1.3~rc1+hg-20120614.a9c0a89c08f2-5
Date: Mon, 30 Jul 2012 21:33:43 +0000
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