原因是NetworkManager 开启导致。关闭NetworkManager服务，否则会报错master connection not found or invalid。主要是因为NetworkManager接管了网卡启动，将NetworkManager停掉，并启动 network 服务来接管网卡服务，请查看如下四条命令：
1 service NetworkManager stop 2 chkconfig NetworkManager off 3 chkconfig network on 4 service network start