複製虛擬機後，由於CentOS會記住Mac Address，但是重新啟動後會配發一個新的Mac Address 並且新增一個eth1的網卡。
解決方式為將失效的eth0的Mac Address改為新的Mac Address，新的Mac Address在路徑:
[/etc/udev/rules.d/70-persistent-net.rules]中
# 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 0x8086:0x100f (e1000)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:0c:29:d4:99:d3", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"
只要將eth0的Mac Address改為 00:0c:29:d4:99:d3
並且重新啟動網路 >service network restart
