CentOS 7 And MAC Address Munging

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Odd situation: I’ve mentioned before that I have several users for whom I
have to spoof the MAC address, due to a software license. Now, I’ve got net.ifnames=0 biosdevname=0 on the grub2 command line, and I’ve got the spoofed MAC address in /etc/sysconfig/network-sctipts/ifcfg-eth0.

But he had a serious problem – X froze, and he thought to reboot, rather than call me. It came up with the actual MAC. I tried a number of things, including reboots, but the only thing that worked was systemctl stop NetworkManager, ifdown eth0, then ifup eth0, then start NetworkMangler, and all was good.

Yeah, I know, afterwards, I remembered I should have use nmcli….

But the real question is *why* did it fail on the reboot. I find no clues in dmesg, or messages, or boot.log.

Clues for the poor?

mark

2 thoughts on - CentOS 7 And MAC Address Munging

  • Odd situation: I’ve mentioned before that I have several users for whom I
    have to spoof the MAC address, due to a software license. Now, I’ve got net.ifnames=0 biosdevname=0 on the grub2 command line, and I’ve got the spoofed MAC address in /etc/sysconfig/network-sctipts/ifcfg-eth0.

    But he had a serious problem – X froze, and he thought to reboot, rather than call me. It came up with the actual MAC. I tried a number of things, including reboots, but the only thing that worked was systemctl stop NetworkManager, ifdown eth0, then ifup eth0, then start NetworkMangler, and all was good.

    Yeah, I know, afterwards, I remembered I should have use nmcli….

    But the real question is *why* did it fail on the reboot. I find no clues in dmesg, or messages, or boot.log.

    Clues for the poor?

    mark

  • Subject: Re: [CentOS] CentOS 7 and MAC address munging Date: Thu, 18 May 2017 06:22:21 +0100
    From: James Hogarth

    Mostly. Running 3.10.0-514.10.2.el7.x86_64, and yum tells me nothing marked for update (that’s ignoring that we have exclude=kernel* *xorg*
    *nvid* kmod* in yum.conf)
    802-3-ethernet.cloned-mac-address: and the spoofed MAC address.

    Sorry, I don’t understand the above sentence. What property –
    802-3-ethernet.cloned-mac-address? And this is on top of ifcfg-eth0, and all the rest?

    mark

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