I finally had to look into udev a little bit today. I had made some modifications to a RHEL6 guest I have in VMWare ESXi. My trouble started when I converted the storage from thick to thin, due to limited space. I am still not sure why would have caused an issue with network devices, but it did. I ended up with a eth1 device instead of the eth0 device I had previously. I tried removing all the interfaces via vSphere and then adding one, but this only created eth2.

To resolve the issue, I needed to modify the appropriate udev rules. The rule files are located in /etc/udev/rules.d. The file that contained the network interface information was in the 70-persistent-net.rules file.

My /etc/udev/rules.d/70-persistent-net.rules contained the following:

# This file was automatically generated by the /lib/udev/write_net_rules
# program, run by the persistent-net-generator.rules rules file.
#
# You can modify it, as long as you keep each rule on a single
# line, and change only the value of the NAME= key.

# PCI device 0x15ad:0x07b0 (vmxnet3) (custom name provided by external tool)
SUBSYSTEM==”net”, ACTION==”add”, DRIVERS==”?*”, ATTR{address}==”00:0c:29:9a:99:76″, ATTR{type}==”1″, KERNEL==”eth*”, NAME=”eth0″

# PCI device 0x15ad:0x07b0 (vmxnet3)
SUBSYSTEM==”net”, ACTION==”add”, DRIVERS==”?*”, ATTR{address}==”00:0c:29:70:fa:e5″, ATTR{type}==”1″, KERNEL==”eth*”, NAME=”eth1″

# PCI device 0x8086:0x100f (e1000) (custom name provided by external tool)
SUBSYSTEM==”net”, ACTION==”add”, DRIVERS==”?*”, ATTR{address}==”00:0c:29:70:fa:e5″, ATTR{type}==”1″, KERNEL==”eth*”, NAME=”eth0″

# PCI device 0x15ad:0x07b0 (vmxnet3)
SUBSYSTEM==”net”, ACTION==”add”, DRIVERS==”?*”, ATTR{address}==”00:0c:29:70:fa:ef”, ATTR{type}==”1″, KERNEL==”eth*”, NAME=”eth2″

I simply removed all eth1 and eth2 and the eth0 (vmxnet3) entries, and rebooted. This took care of the issue.