After a power outage (yes no UPS) CentOs crash I ran into an issue were for some reason or another the physical network adapter became eth1 marked as a different MAC ADDR

there was no ifcfg-eth1 file in /etc/sysconfig/network-scripts

changes to ifcfg-eth0 would not take any affect.

the following steps resolved my issue.

references: https://www.banym.de/linux/centos/change-network-device-name-from-eth1-back-to-eth0

The interface name of a network device increases if the mac address of the physical or virtual network card changes. A common case is if you made a clone of a virtual machine for example via VMware or KVM or replaced a physical network card in a non virtualized server.

If it’s a CentOS 6 machine you need to change 2 files to rename the interface for example from eth1 back to eth0.

One file is the udev rule for network devices which is located here:

/etc/udev/rules.d/70-persistent-net.rules

Copy the new mac address to the line of your eth0 rule and delete the new rule for eth1.

# PCI device 0x15ad:0x07b0 (vmxnet3)SUBSYSTEM==”net”, ACTION==”add”, DRIVERS==”?*”, ATTR{address}==”00:50:56:b2:23:e0″, ATTR{type}==”1″, KERNEL==”eth*”, NAME=”eth0″

Modify the network configuration located under:

/etc/sysconfig/network-scripts/ifcfg-eth0

and replace the old ip with the new one and the old mac address with the new mac address.

To be sure everything works fine reboot your machine.