[CentOS] Strange XEN on CentOS HWaddr Address Issue

Tue Aug 4 17:57:11 UTC 2009
Mathew S. McCarrell <mccarrms at gmail.com>

Brett,

I think the following link answers your question about the MAC changes.  You
may find more useful links on the resources page of the Running Xen site
http://runningxen.com/resources/.

http://lists.xensource.com/archives/html/xen-users/2006-02/msg00030.html

If you performed a fresh install without Xen, you would notice that it has
not permanently modified the MAC address of your system.

Hope that helps.

Matt

--
Mathew S. McCarrell
Clarkson University '10

mccarrms at gmail.com
mccarrms at clarkson.edu
1-518-314-9214



On Tue, Aug 4, 2009 at 1:30 PM, Brett Serkez <bserkez at gmail.com> wrote:

> > Maybe because you are looking at the bridge's mac and not the
> > ethernet's which would be peth0.
>
> No I am not.  dmesg shows the kernel messages at boot and it is
> looking at the physical device, let's not get distracted, the issue is
> clear in this regard.  As I previously stated, this happens even when
> uninstalling XEN and booting off the non-XEN kernel since the install
> of XEN.
>
> > indeed, AFAIK all hardware adapters start with 00. This must have been
> set
> > in the BIOS or with a boot option or in the network config.
>
> This was helpful, gave me places/incentive to continue looking.
>
> In /etc/sysconfig/network-scripts/ifcfg-eth1 I found:
>
> # Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet
> DEVICE=eth1
> BOOTPROTO=none
> HWADDR=00:40:F4:CE:E6:7B
>
> So now I know what the original MAC address was.
>
> Here is where it gets interesting.  The following file was modified at
> the date/time that the XEN kernel was first booted:
>
> /etc/sysconfig/hwconf
>
> and it has fe:ff:ff:ff:ff:ff  for BOTH network adapters:
>
> desc: "Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet"
> networfe:ffddr: fe:ff:ff:ff:ff:ff
> vendorId: 10ec
> deviceId: 8169
> subVendorId: 10ec
> subDeviceId: 8169
> pciType: 10
>
> desc: "Intel Corporation 82562EZ 10/100 Ethernet Controller"
> network.hwaddr: fe:ff:ff:ff:ff:ff
> vendorId: 8086
> deviceId: 1050
> subVendorId: 8086
> subDeviceId: 303a
>
> Everything I'm finding is re-enforcing my original theory that XEN
> modified the hwaddr of this NIC.
>
> The question continues to be what caused this and how to change it
> back.  Given this is a stock system, I have to believe others must
> have/may run into this issue.
>
> Brett
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