From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: What makes a good fake MAC address? Date: Wed, 22 Apr 2009 15:59:09 -0700 Message-ID: <20090422155909.0d2fdffd@s6510> References: <20090423070442.1e643b5b.ipng@69706e6720323030352d30312d31340a.nosense.org> <200904221515.05459.inaky@linux.intel.com> <20090422152539.7a7e073a@s6510> <200904221538.10964.inaky@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Mark Smith , netdev@vger.kernel.org To: Inaky Perez-Gonzalez Return-path: Received: from mail.vyatta.com ([76.74.103.46]:59023 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751173AbZDVW7L (ORCPT ); Wed, 22 Apr 2009 18:59:11 -0400 In-Reply-To: <200904221538.10964.inaky@linux.intel.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 22 Apr 2009 15:38:10 -0700 Inaky Perez-Gonzalez wrote: > On Wednesday 22 April 2009, Stephen Hemminger wrote: > > On Wed, 22 Apr 2009 15:15:05 -0700 > > > > Inaky Perez-Gonzalez wrote: > > > On Wednesday 22 April 2009, Mark Smith wrote: > > > > Hi Inaky, > > > > > > > > (please CC me, I'm not on the list) > > > > > > > > "The problem with using a zero mac address is that it confuses > > > > the bridging software (and maybe others). I was wondering, what > > > > would be a fake mac address we could put in there that is legal > > > > for this kind of "faking"? [or the closest thing to legal?]" > > > > > > > > Since you're from an organisation with an OUI allocation or > > > > two, I think a real Intel one would be best. It then wouldn't > > > > be fake, and no matter where it was exposed (host only, local > > > > network, or globally e.g. in IPv6 node addresses), it would be > > > > guaranteed not to collide with any other addresses (unless > > > > Intel make error an error in their own OUI administration.) > > > > > > It doesn't really work, because it is for the "from" end of the > > > connection; as said somewhere else in the thread, the WiMAX link > > > is P2P, IP only. The card has a local address, that we use for > > > the "to" field, but for the from, we need to fake an address from > > > the network -- which is not necessarily an intel device :) > > > > > > So maybe local addresses would not be the right choice, and > > > clearly Intel assigned ones neither :) > > > > You need a from address for the bridge to be able to populate its > > forwarding table. If remote end is always same, just get some random > > address at start of tunnel and reuse it. > > Nope, the remote end will change as you move around from base station > to base station :( > Then don't bridge.