From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Cc: Jason Lunz <lunz@falooley.org>
Subject: Re: [uml-devel] Re: Randomize on MAC address when bringing up ethernet iface
Date: Wed, 31 May 2006 19:24:03 +0200 [thread overview]
Message-ID: <200605311924.03674.blaisorblade@yahoo.it> (raw)
In-Reply-To: <e5kik9$k5d$1@sea.gmane.org>
On Wednesday 31 May 2006 19:09, Jason Lunz wrote:
> blaisorblade@yahoo.it said:
> > 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.
> I agree this makes sense. Currently I'm forced to do it in a script.
>
> It's especially silly that uml virtual ethernet devices *don't* get
> random mac addresses automatically, while tuntap virtual ethernet
> devices *do* (in the same kernel tree!).
> > Conditions: the broadcast bit must be 0 and the "locally-assigned address
> > flag" must be 1 (as likely we already do).
>
> random_ether_addr() in include/linux/etherdevice.h already takes care of
> this.
Correct, it would have been a pity if this didn't exist. Thanks a lot!
But because of the bit order problem, when I saw on some messages randomly
assigned MACs (either for TAP or for some other interfaces) I wrongly thought
they were global MACs (I expected to see 0x80 as highest-order bit, for
multicast/broadcast, and 0x40 as "local" flag).
--
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
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next prev parent reply other threads:[~2006-05-31 17:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-30 18:12 [uml-devel] Randomize on MAC address when bringing up ethernet iface Blaisorblade
2006-05-31 17:09 ` [uml-devel] " Jason Lunz
2006-05-31 17:24 ` Blaisorblade [this message]
2006-05-31 19:05 ` [uml-devel] " Jeff Dike
2006-05-31 19:56 ` [uml-devel] " Jason Lunz
2006-06-01 8:40 ` [uml-devel] " Blaisorblade
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