== What controls Red Hat Enterprise's ethN device names

Since I just went digging for this [[the other day
RHELEthernetNamingProblem]], here's what I know about what controls
what Ethernet devices get named on Red Hat Enteprise (and probably
also on Fedora, but I haven't looked at my Fedora systems in this
level of detail).

* if _kudzu_ is enabled, it uses _/etc/sysconfig/hwconf_ to name
  everything. If there is no such file or the data in it doesn't
  match current reality, various bad things happen.

  (You can probably hand-edit the file if necessary.)

* otherwise, interface naming is controlled by the _HWADDR_ setting
  in the _ifcfg-*_ files in _/etc/sysconfig/network-scripts_. If
  there is no Ethernet address specified, you get no renaming.

The ifcfg files are used by both _udev_ and the _ifup_ scripts
that actually bring interfaces up and so on. When udev detects a
new network device (including at boot, I believe), it runs
((/lib/udev/rename_device)), which searches the _ifcfg-*_ files for a
_HWADDR_ that matches the new device and uses the _DEVICE_ setting from
that file to give a name to the new interface.

(A network device that is hotplugged after system boot also winds
up running _/etc/sysconfig/network-scripts/net.hotplug_.)

During boot, the order of operation is _udev_ first, then _kudzu_,
and finally the _network_ init script winds up _ifup_'ing all of the
interfaces that are supposed to be running, potentially undoing any
damage _kudzu_ did (if _kudzu_ left the ifcfg configuration files
along, which is unlikely).

(You may gather that I have a pretty low opinion of _kudzu_; in fact, I
have been turning it off on most of my systems for years. It was left
enabled on this RHEL system mostly because I hadn't taken the time to
audit what init scripts were getting run.)