Error: Connection activation failed: Device not managed by NetworkManager

在虛擬機器中，啟動eth0 網路卡時報錯：

Error: Connection activation failed: Device not managed by NetworkManager

於是在網上找了解決方法：

1. Remove Network Manager from startup Services.

#chkconfig NetworkManager off

2. Add Default Net Manager

#chkconfig network on

3.Stop NetworkManager first

#service NetworkManager stop

4.Start Default Manager

#service network start

提示：

Bringing up loopback interface:                            [  OK  ]

Bringing up interface eth0: 

Determining IP information for eth0... done.

                                                           [  OK  ]

RTNETLINK answers: File exists

再重啟一下網路就好了

service network restart