From mboxrd@z Thu Jan 1 00:00:00 1970 From: "SourceForge.net" Subject: [ kvm-Bugs-1858946 ] Qemu doesn't warns user about incorrect MAC Address Date: Mon, 26 May 2008 10:14:14 -0700 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" To: noreply@sourceforge.net Return-path: Received: from lists.sourceforge.net ([66.35.250.206]:46690 "EHLO mail.sourceforge.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754480AbYEZROP (ORCPT ); Mon, 26 May 2008 13:14:15 -0400 Sender: kvm-owner@vger.kernel.org List-ID: Bugs item #1858946, was opened at 2007-12-27 09:20 Message generated for change (Comment added) made by aliguori You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1858946&group_id=180599 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open >Resolution: Invalid Priority: 5 Private: No Submitted By: Technologov (technologov) >Assigned to: Anthony Liguori (aliguori) Summary: Qemu doesn't warns user about incorrect MAC Address Initial Comment: NOTE: This is a qemu problem/lack-of-feature, not a KVM one. I Tried to launch 2 VMs connected back-to-back on the same host, but nothing worked, so I wasted a lot of time figuring it out, and my time could be saved, if Qemu could give proper warning on user stupidity/incorrect action. At the end, my colleague pointed me to this problem. Actually I used MAC addresses, that begin with "01:xx:xx:xx:xx:xx" which are multicast MAC addresses, and are illegal to assign them to NIC, and neither the guest OS (Windows XP), and not Qemu didn't complain about that, but the network simply didn't work. The NIC (RTL8139) was detected and installed by the guest OS, without a problem. The full list of illegal MAC addresses, that are Multicast/Broadcast is listen below: http://www.cavebear.com/archive/cavebear/Ethernet/multicast.html Correct behavior would be: to warn a user of his incorrect action, but continue running a VM. Now I just wasted 6 hours. Please improve Qemu to save other people's time... -Alexey Technologov, 26.Dec.2007. ---------------------------------------------------------------------- >Comment By: Anthony Liguori (aliguori) Date: 2008-05-26 13:14 Message: Logged In: YES user_id=120449 Originator: NO No MAC address is valid unless you have been assigned it. It's the user's responsibility to ensure that the MAC addresses they are using are valid and won't cause conflicts on their network. Blacklisting a certain group of MAC addresses doesn't make the problem much better because people can still end up using "random" MAC addresses which are actually valid on their network. We need to encourage people not to use "random" MAC addresses, it's always wrong. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1858946&group_id=180599