网络异常：Failed to start LSB: Bring up/down networking

一、遇到的问题

1、重启机器后，网络异常报：Failed to start LSB: Bring up/down networking

经常会遇到虚拟机重启后，无法建立服务器远程连接的问题，经排查网络不通；

重启网络服务

#重启网络：注意CentOS6需要使用service network restart命令
[root@hu ~]# systemctl restart network
Restarting network (via systemctl):  Job for network.service failed. See 'systemctl status network.service' and 'journalctl -xn' for details.

#执行'systemctl status network.service'进一步排查
[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 2021-12-29 09:30:10 CST; 1min 5s ago
12月 29 09:30:10 localhost.localdomain network[2920]: RTNETLINK answers: File exists
...
...
12月 29 09:30:10 localhost.localdomain systemd[1]: network.service: control process exited, code=exited status=1
12月 29 09:30:10 localhost.localdomain systemd[1]: Failed to start LSB: Bring up/down networking.
12月 29 09:30:10 localhost.localdomain systemd[1]: Unit network.service entered failed state.

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二、解决方案

1.禁用NetworkManager

#关闭NetworkManager服务,重启机器后会失效
[root@hu ~]# systemctl stop NetworkManager

#永久关闭NetworkManager服务,重启机器后不会失效
[root@hu ~]# systemctl disable NetworkManager

2.关闭防火墙

# 查看防火墙状态
[root@hu ~]# firewall-cmd --state
running			---运行中，即开启状态

# 关闭防火墙
[root@hu ~]# systemctl stop firewalld

# 查看是否关闭成功
[root@hu ~]# firewall-cmd --state
not running   	---不在运行中，即关闭状态

3.关闭selinux

#查看selinux状态
[root@hu ~]# getenforce
Enforcing		---表示开启状态

# 临时关闭
[root@hu ~]# setenforce 0		---立即生效，重启后失效

# 永久关闭，修改selinux配置文件。	---重启后生效
[root@hu ~]# vim /etc/selinux/config
...
# 将SELINUX的值修改为disabled
SELINUX=disabled
...

# 关闭后再次查看是否关闭成功
[root@hu ~]# getenforce
Disabled		---表示关闭状态

4.重启机器&重启网络

#重启机器
[root@hu ~]# reboot
...
...

# 再次重启网络,无报错
[root@hu ~]# systemctl restart network

# 查看网络是否重启成功
[root@hu ~]# ip a
...
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:0e:b4:0d brd ff:ff:ff:ff:ff:ff
    inet 192.168.139.128/24 brd 192.168.63.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe0e:b40d/64 scope link
       valid_lft forever preferred_lft forever
...

ens33网卡已重启成功
至此，已解决网络重启不了的问题。

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