J-forum

Posted: **Mon Aug 26, 2019 11:54 am**

Linux version: Ubuntu 16.04 server amd64, VirtualBox VM

Occasionally network access stopped to work on the server.
Command ifconfig gives only lo interface.

: ifconfig.lo.png (6.24 KiB) Viewed 242 times

First attempt was to change network adapter in VM settings.
I even changed MAC and added an extra network adapter.
No result yet

: VirtualBox. network settings; VM settings.png (18.51 KiB) Viewed 242 times

It looks there was some problem with network drivers.
No Internet connection.

When I need to fix something in Windows and nothing works, I normally get Windows installer (CD .. or even USB stick).
I goggled possibility to do similar things using Linux live CD.

"The easiest way is boot from an installation media and then use chroot" (https://askubuntu.com/questions/319798/ ... -on-ubuntu)

And I found good explanation on that:
http://ubuntu.fliplinux.com/1836.html (Russian) - exactly related to the subject
https://help.ubuntu.com/community/LiveCdRecovery (English)

The idea was to re-install network manager

In case of having Internet connection, it would be done in the following way

Code: Select all

sudo apt-get install network-manager

Without Internet (network does not work), I needed to get Ubuntu 16.4 iso image. Old Gitlab server has the same version.

When I boot from Live CD, I found single HDD and its main partition as /dev/sda1.

: fdisk output; sda1.png (58.08 KiB) Viewed 242 times

In terminal window I executed the following commands

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sudo mount /dev/sda1 /mnt
sudo mount --bind /sys /mnt/sys
sudo mount --bind /proc /mnt/proc
sudo mount --bind /dev /mnt/dev
sudo mount --bind /dev/pts /mnt/dev/pts
sudo cp /etc/resolv.conf /mnt/etc/
sudo chroot /mnt

: chroot.png (30.52 KiB) Viewed 242 times

Now further installations will be applied to real HDD, and not to live (temp) system

Internet connection works on the Live (temp) system

: two network interfaces.png (61.53 KiB) Viewed 242 times

First I had to install latest updates to current Ubuntu 16.4

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sudo apt-get update

sudo apt-get upgrade (desired... but probably not really necessary)
Upgrade may take a while since more than 1 Gbytes should be downloaded and installed.

Then network manager can be (re)installed

Code: Select all

sudo apt-get install network-manager

This command did not work. There was error message with recommendation to execute 'sudo dpkg --configure -a'
After that command (executed for a while), I tried to install network manager again

: dpkg.png (11.5 KiB) Viewed 242 times

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sudo dpkg --configure -a

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sudo apt-get install network-manager

I restarted the server without Live CD. And it appeared network is working!!!

Normally I install Midnight Commander (mc). I like GUI. And that allows me to browse files easily.

Code: Select all

sudo apt-get install mc

That is all.

J-forum

How to recover network

How to recover network