当执行 ifup ens33 出现错误：

[root@localhost ~]# ifup ens33

Error: Connection activation failed: No suitable device found for this connection (device lo not available because device is strictly unmanaged).

解决办法：
[root@localhost ~]# chkconfig NetworkManager off

Note: Forwarding request to ‘systemctl disable NetworkManager.service’.
Removed symlink /etc/systemd/system/multi-user.target.wants/NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service.
Removed symlink /etc/systemd/system/network-online.target.wants/NetworkManager-wait-online.service.

[root@localhost ~]# chkconfig network on
[root@localhost ~]# service NetworkManager stop

Redirecting to /bin/systemctl stop NetworkManager.service

[root@localhost ~]# service network start

Starting network (via systemctl): [ OK ]