ubuntu 20.04无法连接网络，网线灯不亮，network-manager也启动不了

背景

系统编程只读的了，进入到initramfs模式，执行了下边语句，发现不小心把windows也给执行了，报错很多乱码，强制退出

执行

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fsck -y /dev/sdb4
fsck -t ext4 /dev/sdb5  -y ## windows

时强制退出了导致很多文件损坏,虽然能正常开机了

但是terminal打不开，NetworkManager启动不了，网卡也掉了，折腾了好久才解决重新连上网

解决办法

看系统日志报错,网线灯也不亮

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bus-manager: fatal failure to acquire D-Bus service "org.freedesktop.NetworkManager: GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: Connection ":1.293" is not allowed to own the service "org.freedesktop.NetworkManager" due to security policies in the configuration fil

挂载网卡

找个可以打开的控制台工具打开，我用vscode打开控制台
执行语句挂在网卡,网卡灯就亮了，我的网卡名字叫eno1,有些网卡叫eth0什么的多试试就行

ifconfig eno1 up

启动network-manager

启动网卡还是失败，报上边的错误

sudo service network-manager start

创建一个文件叫org.freedesktop.NetworkManager.conf,拷贝到

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sudo cp org.freedesktop.NetworkManager.conf /etc/dbus-1/system.d/

内容如下：

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<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <!-- Only root can own the service -->
  <policy user="root">
    <allow own="org.freedesktop.NetworkManager"/>
  </policy>

  <policy context="default">
    <allow send_destination="org.freedesktop.NetworkManager"/>
    <allow send_destination="org.freedesktop.NetworkManager"
           send_interface="org.freedesktop.DBus.Properties"/>
    <allow send_destination="org.freedesktop.NetworkManager"
           send_interface="org.freedesktop.DBus.Introspectable"/>
    <allow send_destination="org.freedesktop.NetworkManager.User"
           send_interface="org.freedesktop.DBus.Properties"/>
    <allow send_destination="org.freedesktop.NetworkManager.User"
           send_interface="org.freedesktop.DBus.Introspectable"/>
  </policy>

</busconfig>

再次启动network-manager,启动成功

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sudo service network-manager start

查看窗台

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sudo service network-manager status

获取ipv4地址

启动成功但是还是无法获取ipv4地址

需要创建一个/etc/network/interfaces文件，内容如下：网卡改成你自己的

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 auto lo
 iface lo inet loopback
 auto eno1
 iface eno1 inet dhcp
 auto eno1
 iface eno1 inet dhcp

执行

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sudo dhclient

就有ipv4地址了，可以正常连接