运行#/etc/init.d/network restart, 重启网络连接时出现以下错误：
Bringing up interface eth0: Error:Connection activation failed:Device not managed by NetworkManager
在csdn上找到了解决方案，如下：（http://blog.csdn.net/swiftshow/article/details/7367733#）
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.and then start Default Manager
#service network start
运行完了命令，还会出现
RTNETLINK answers: File exists
RTNETLINK answers: File exists
RTNETLINK answers: File exists
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然后网络就能用啦。
