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博客地址：http://blog.csdn.net/qq_21398167
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1、运行 service network restart 出现下面错误
Restarting network (via systemctl): Job for network.service failed. See 'systemctl status network.service' and 'journalctl -xn' for details.
2、依据上面的提示，运行“systemctl status network.service”输出下面的类似信息：
[root@localhost ~]# systemctl status network.service
network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network)
Active: failed (Result: exit-code) since三 2014-11-05 15:30:10 CST; 1min 5s ago
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
11月 05 15:30:10 localhost.localdomain systemd[1]: network.service: control process exited, code=exited status=1
11月 05 15:30:10 localhost.localdomain systemd[1]: Failed to start LSB: Bring up/down networking.
11月 05 15:30:10 localhost.localdomain systemd[1]: Unit network.service entered failed state.
3、解决的办法（因为centos7中没有70-persistent-net.rules这个文件，复制出来的虚拟机(vmware）须要改动mac地址），就是改动mac地址。
4、怎样查看centos7复制出来的虚拟机的mac地址，须要运行 “ip addr”，输出例如以下的类似信息：
[root@localhost ~]# ip addr
1: lo:
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eno16777736:
link/ether00:0f:19:10:12:f1 brd ff:ff:ff:ff:ff:ff
inet 192.168.38.135/24 brd 192.168.38.255 scope global dynamic eno16777736
valid_lft 1681sec preferred_lft 1681sec
inet6 fe80::20c:11aa:ae11:4fe4/64 scope link
valid_lft forever preferred_lft forever
注意上面加粗加红的字，这就是新的mac地址。
接下来就剩下改动ifcfg-XXX文件了。仅仅改动HWADDR就能够了。接下来运行service network restart就正常了。
《二》
假设还是启动失败 查看是否有例如以下错误信息
Nov 23 22:09:07 hdcoe02 network[597]: Bringing up loopback interface: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Nov 23 22:09:07 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Nov 23 22:09:08 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Nov 23 22:09:08 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo' Nov 23 22:09:08 hdcoe02 network[597]: [ OK ]
Nov 23 22:09:08 hdcoe02 network[597]: Bringing up interface enp0s25: Error: Connection activation failed: Connection 'enp0s25' is not available on the device enp0s25 at this time.
设定开机启动一个名为NetworkManager-wait-online服务，命令为：
systemctl enable NetworkManager-wait-online.service
《三》
我也是上面方法都測试完了 一直不成功，最后发现时由于在VMware 虚拟机里面的系统 右上角显示的连接都没有连接上，尽管报错都一样，最后我在虚拟机设置里面将原来的网络适配器删掉。又一次建了一个新的网络适配器，这次进去，显示连接成功。再用上面的方法，问题解决。