背景

克隆了一台虚拟机（Centos7）启动之后连接不上网络，执行ip addr发现没有网卡的信息，重启网卡失败，按照提示查看一下状态

[root@centos7 ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[root@centos7 ~]# systemctl status network.service
● network.service - LSB: Bring up/down networking
   Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled)
   Active: failed (Result: exit-code) since Mon 2017-03-13 23:24:37 CST; 16s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 2878 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)

Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 systemd[1]: network.service: control process exited, code=exited status=1
Mar 13 23:24:37 centos7 systemd[1]: Failed to start LSB: Bring up/down networking.
Mar 13 23:24:37 centos7 systemd[1]: Unit network.service entered failed state.
Mar 13 23:24:37 centos7 systemd[1]: network.service failed.

去查了一下，根据查到的修改/etc/sysconfig/network-scripts/ifcfg-XXX文件，添加mac地址()等方式并未成功解决问题，后来查到通过禁用NetworkManager成功解决问题，在此记录一下。

解决方法

禁用NetworkManager

systemctl stop NetworkManager
systemctl disable NetworkManager

启动网卡，解决！

参考资料