[CentOS] turning off udev for eth0

m.roth at 5-cent.us m.roth at 5-cent.us
Tue Jan 3 20:21:56 UTC 2012

James B. Byrne wrote:
> On Tue, January 3, 2012 11:58, m.roth at 5-cent.us wrote:
>> On the physical box, how many NICs are there?
> There are two physical NICs. Eth0 is the WAN, Eth1 is the
> LAN.  The vm guests are supposed to only be accessible via
> the WAN.  The prototype is configured with only one NIC
> connected to the bridge device (vnet0 - bridge Br0).
> Do physical attributes of the host override the configured
> virtual attributes of a guest?

Dunno 'bout guests - I haven't worked with them, much, except VMware.

man udev:
     udev provides a dynamic device directory containing only the files for
     actually present devices. It creates or removes device node files in
     the /dev directory, or it renames network interfaces.

     Usually udev runs as udevd(8) and receives uevents directly from the
     kernel if a device is added or removed from the system.

     If udev receives a device event, it matches its configured rules
     against the available device attributes provided in sysfs to identify
     the device. Rules that match may provide additional device information
     or specify a device node name and multiple symlink names and instruct
     udev to run additional programs as part of the device event handling.

So it's good, in some ways, but...
>> Have you edited /etc/udev/rules.d in the prototype setup?
> I had previously removed the contents of the
> 70-persistent-net.rules file on the prototype.   However,
> I did not pay enough attention to the fact that this file
> is rewritten upon startup.  So I was getting the eth0 i/f
> added back into it every time I started the prototype to
> perform updates.
> If I remove the contents of this file just before shutting
> down the prototype then the interface problem with cloning
> disappears.
> Thanks for the hint.

Sure. Those persistant-net-rules can really getcha. I've done a lot of
upgrades (to 6.x) via rsync from servers I'd built directly, and that
caught me a number of times, till I Got It.

        mark "and got rid of eth0,1,2,3,4,5...."

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