网上常见的解决方法是:
sudo service network-manager stop
sudo rm /var/lib/NetworkManager/NetworkManager.state
sudo service network-manager start
sudo gedit /etc/NetworkManager/nm-system-settings.conf
把false改成true
sudo service network-manager restart
但我这个例子里面提示没有 network-manager 服务,也懒得折腾network-manager,后来发现在网络配置文件 /etc/sysconfig/network-scrips/ifcg-eth0 里面,增加“NM_CONTROLED=yes”,然后重启服务器即可。