Linux – get the original MAC address after it has been changed

linuxmac address

I am using some linux machines that have had their MAC address changed. I would like to be able to read it back with a shell script.

Is the original MAC address stored anywhere except the sticker on the box?
How do I bring back the original hardware address?

Best Answer

you can check you dmesg logs it will report the hardware MAC address as seen on boot.

on one of my boxes the output looks like:

gbeech@ny-man01:~$ dmesg | grep eth0
[    6.533181] eth0: Broadcom NetXtreme II BCM5709 1000Base-T (C0) PCI Express found at mem d6000000, IRQ 36, node addr 00:21:9b:a0:b7:cc

what you are interested in is the node addr 00:21:9b:a0:b7:cc bit at the end

Related Solutions

What range of MAC addresses can I safely use for the virtual machines

There are actually 4 sets of Locally Administered Address Ranges that can be used on your network without fear of conflict, assuming no one else has assigned these on your network:

x2-xx-xx-xx-xx-xx
x6-xx-xx-xx-xx-xx
xA-xx-xx-xx-xx-xx
xE-xx-xx-xx-xx-xx

Replacing x with any hex value.

Linux – Counting traffic to destination MAC address using ebtables/iptables

IPTables supports traffic accounting. You should just be able to setup an IPtables rule matching the mac address you are interested in, then look at it's counters to see what kind of traffic it's pushing. Note that you can't use this to look at traffic for other machines on the LAN, it will only be for traffic to or from the machine it's running on.

Best Answer

Related Solutions

What range of MAC addresses can I safely use for the virtual machines

Linux – Counting traffic to destination MAC address using ebtables/iptables

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