給電腦加了內存條，然後啓動虛擬機，發現xshell連不上虛擬機了
ifconfig一看 只剩下 lo和virbr0
如果用ifconfig -a 可以看到ens33
修改了靜態IP
1、配置文件所在目錄爲 /etc/sysconfig/network-scripts
cd /etc/sysconfig/network-scripts
2、打開配置文件進行修改，建議在修改之前先備份
cp ifcfg-ens33 ifcfg-ens33.bak
vim ifcfg-ens33
3、參數配置如下
重啓網絡： systemctl status network.service
報錯如下：
● 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 Fri 2017-08-04 08:20:31 CST; 1min 44s ago
Docs: man:systemd-sysv-generator(8)
Process: 62726 ExecStop=/etc/rc.d/init.d/network stop (code=exited, status=0/SUCCESS)
Process: 63183 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 network[63183]: RTNETLINK answers: File exists
Aug 04 08:20:31 CT71 systemd[1]: network.service: control process exited, code=exited status=1
Aug 04 08:20:31 CT71 systemd[1]: Failed to start LSB: Bring up/down networking.
Aug 04 08:20:31 CT71 systemd[1]: Unit network.service entered failed state.
Aug 04 08:20:31 CT71 systemd[1]: network.service failed.
解決方法：
1. systemctl stop NetworkManager
2. systemctl disable NetworkManager
3.systemctl start network.service
如下圖
再次ifconfig如上圖 一切OK
查看網絡是否連接成功：
網絡連接成功， 問題解決！！！