From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from [10.3.1.93] (helo=sc8-sf-list1-new.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1FlU28-0002w8-9W for user-mode-linux-devel@lists.sourceforge.net; Wed, 31 May 2006 09:59:00 -0700 Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1FlU28-0006k6-Ea for user-mode-linux-devel@lists.sourceforge.net; Wed, 31 May 2006 09:59:00 -0700 Received: from smtp008.mail.ukl.yahoo.com ([217.12.11.62]) by mail.sourceforge.net with smtp (Exim 4.44) id 1FlU24-0005G3-MI for user-mode-linux-devel@lists.sourceforge.net; Wed, 31 May 2006 09:59:00 -0700 From: Blaisorblade MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605302013.00091.blaisorblade@yahoo.it> Subject: [uml-devel] Randomize on MAC address when bringing up ethernet iface Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 30 May 2006 20:12:59 +0200 To: Jeff Dike Cc: user-mode-linux-devel@lists.sourceforge.net I've being thinking to this and I'm wondering why we shouldn't do it. When we have set no IP or 0.0.0.0, which is not a unique IP, and we bring it up, we should choose a random MAC to use. Conditions: the broadcast bit must be 0 and the "locally-assigned address flag" must be 1 (as likely we already do). For which bits they are, I've a doubt. On Tanenbaum's book they're marked as the two most significant (leftmost) bits (broadcast being the most significant one), but since we've longly known the broadcast bit is the lowest-order one of the highest bit, I suspect that MACs are read in little-endian bit order (which likely implies the same for the whole packets). I can't verify this, but bytes in many fields are moved to be in network order i.e. big-endian order (MACs are always used in the network order). So possibly bit-swap is also used before going on the wire. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade Chiacchiera con i tuoi amici in tempo reale! http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com ------------------------------------------------------- All the advantages of Linux Managed Hosting--Without the Cost and Risk! Fully trained technicians. The highest number of Red Hat certifications in the hosting industry. Fanatical Support. Click to learn more http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel