Re: Managing interface with random MAC address

[Russ Dill <russ dill gmail com>]

On Thu, Mar 5, 2009 at 6:53 AM, Kay Sievers <kay sievers vrfy org> wrote:
> On Thu, Mar 5, 2009 at 13:33, Dan Williams <dcbw redhat com> wrote:
>> On Thu, 2009-03-05 at 01:25 -0700, Russ Dill wrote:
>>> I have an embedded device known as a beagle board that draws power
>>> from my USB port (shows up as usb0). When it boots, it presents itself
>>> as a USB ethernet device. I want to share my connection with the
>>> device from network manager.
>>>
>>> Two problems: The first is that network manager sees an unmanaged
>>> device and tries to obtain an IP address, the second, I can't seem to
>>> setup an automatic share my connection connection since every time the
>>> board boots, it has a different hardware address. Any tips?
>>
>> What is the USB serial number of the device?  The core problem here is
>> that if there's no unique identifier for the device, there's no way to
>> lock a specific connection to that device, and thus any generic Wired
>> connection will be used instead.
>>
>> Run "lsusb -v" and look for the iSerial field; is that field something
>> other than 0?  Do other beagle boards present other serial numbers?
>>
>> Do you want to keep the wired device unmanaged and ignored by
>> NetworkManager?  You said "sees an unmanaged device and tries to obtain
>> an IP address", but NM should be ignoring unmanaged devices.  However,
>> that mechanism depends on HAL UDIs and thus the random MAC address may
>> well be confusing it.
>
> A random MAC address is defined by a bit in the MAC address itself.
> Maybe these devices should be special handled. At least the MAC should
> not be stored somewhere on the system.
>
> The udev persistent netif name rule generator does this:
>  # do not use "locally administered" MAC address
>  ENV{MATCHADDR}=="?[2367abef]:*", ENV{MATCHADDR}=""
>

Yes, the MAC address always has that bit set and so the udev
persistent netif name rule generator doesn't touch it.