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.