[SOLVED] Upgrade from 14.04 to 18.04 stops internet access via missing DNS

[frankus333]

G'day folks

I am restarting this thread with updated info gained from the original thread (https://www.kubuntuforums.net/showth...t-access-eeePC) as that thread is no longer being responded to for over 2 weeks now.

I recently upgraded my Kubuntu 14.04 to 18.04 and it seems to be mostly working, despite the big jump, but has lost internet access via both WLAN and Ethernet. They both are connecting to the router, but won't reach internet sites. Firefox and Chromium can't get out, and neither can software updater or Muon. Chromium shows DNS_PROBE_BAD_CONFIG. Everything in Connections-System Settings Module seems normal.

Checking the network settings via the general settings tab opens a window that shows a tab with DNS info. Only one server was listed: 127.0.0.53. I added the two DNS server addresses for my ISP, and I can now reach the internet with both ethernet and WiFi.

The problem is that those DNS server addresses don't stick through a reboot, so have to be added in again for each session.

During the update, I was asked about replacing or retaining just one configuration file, and I opted to replace it with the latest. I think it had something to do with networking, but can't remember for sure. (Hopefully my choice was not automatically applied to any other files/configurations replacement options.) I probably should have opted to retain the existing file?

I am wondering if someone can tell me which configuration file(s) I need to update to get the DNS addresses to stick through a reboot.

System information requested for posts here:
eeePC 1000H 32 bit notebook, quadruple booted: Kubuntu 18.04, LM17.3KDE, LM18XFCE, Win7 Pro. HDD SATA 160GB total; 57GB NTFS shared Data partition, no opotical drive.
Kubuntu kernel 4.15.0-43-generic, Plasma 5.12.17, RAM 2GB DDRII-533/CL4 Single channel, Processor Intel Atom CPU N270 @ 1.6GHz, Graphics Intel Mobile 945GSE. GRUB 2.02. WiFi card Ralink RT2790 Wireless 802.11n 1T/R2 PCIe, driver rt2800pci.

Thanks for any assistance with this specific DNS settings configuration.

[Snowhog]

I believe that you will ultimately be suggested, that once you (temporarily) establish a working network connection, that you go into KNetwork Manager and set up two new connections, one for WiFi and the other for your cable connection, ensuring that both have the correct settings. Switch to each and test. If both work as expected, delete the one that you are having to tweak. Close and reboot and retest the connection.

As to 'why' this happened, almost a certainty that it was caused by:

During the update, I was asked about replacing or retaining just one configuration file, and I opted to replace it with the latest. I think it had something to do with networking,....

And then,

I probably should have opted to retain the existing file?

YES. When ever you make changes to the default configuration of system files, when any update comes in that includes those configuration files, you will always be asked if you want to replace or keep the existing file(s). You always want to say YES, else you will end up with a replaced file in it's default configuration; not what you want.

[frankus333]

Thanks Snowhog

I can't find anything called KNetwork Manager, even using the search option in the Application Launcher. The window (3 tabs) where I can set DNS servers is called "Network Settings". The window (5 tabs) where connections settings are is called "Connections - System Settings Module". I can't see an option to add new connections in either set of windows.

However, with the connections working with the manual setting of the DNS servers, I changed a setting for each of the connections, just so that the Apply button became activated, then selected Apply after changing the setting back. Unfortunately, this did not survive a reboot.

Next I deleted all the connections, and selected WLAN again from the list of available connections, and set it up as usual. However, this did not survive rebooting either. Finally, I went into the IPv4 tab for WLAN connecction and entered the DNS server addresses in the "Other DNS Servers" diologue slot, sepatated by a comma (,). No luck with this either, although the server listings in the dialogue slot survived.

If someone knows which config file(s) store(s) the DNS server info and where the files are stored, that would be helpful. The procedure for correctly modifying them with root permissions etc would be great.

[Snowhog]

Install nm-tray

Description-en: simple NetworkManager front end nm-tray is a simple NetworkManager front end with information icon residing
in system tray (like e.g. nm-applet). It's a pure Qt application. For
interaction with NetworkManager it uses API provided by
KF5::NetworkManagerQt -> plain DBus communication.

[frankus333]

Thanks Snowhog

I note that according to Muon, nm-tray was released a year ago, has not had any updates, and is not maintained by Canonical. Installing it would mean upgrades to a list of other packages, and installing an even longer list of other packages. Would installing nm-tray allow me to do anything I haven't already done manually? Some of the required upgrades and/or installs may relate to the 200 packages the system updater is currently offering, which I have been holding off until this DNS config is fixed. However, I would rather not install something with such a large impact if it is not giving me anything different/better than what I have done manually.

BTW: regarding offered updates of configuration files. I presume updates are offered because the content or format/layout has been improved, and a package developer wouldn't offer a fresh copy of the original (unmodified) file for no good reason. If so, and the default response should always be to retain your original, modified file, how do you ever get the improved version, and why would improvements be offered if they are always to be declined? I am trying to understand the logic behind this aspect of upgrades.

[jglen490]

How about network-manager? First check with dpkg, maybe something like this:

john@john-Desktop:/etc$ dpkg -l network-manager
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                   Version          Architecture     Description
+++-======================-================-================-=================================================
ii  network-manager        1.10.6-2ubuntu1. amd64            network management framework (daemon and userspac

[Snowhog]

BTW: regarding offered updates of configuration files. I presume updates are offered because the content or format/layout has been improved, and a package developer wouldn't offer a fresh copy of the original (unmodified) file for no good reason. If so, and the default response should always be to retain your original, modified file, how do you ever get the improved version, and why would improvements be offered if they are always to be declined? I am trying to understand the logic behind this aspect of upgrades.

Not a safe assumption. Configuration files must be included with any package that provides for user configuration. And of course, it has to be a 'default configuration file'.

A developer can never know if a user has modified (re:configured) the configuration file for said package. What the package manager does; when it sees an update to a package that is marked as installed on the system; is notify the user that said configuration file exists in the update and that it also exists on your system. You are given the three choices: Accept the installation of the new configuration file; Keep the existing configuration file; Do a side-by-side comparison of both files (experimental) to see what is different between the two. But what the end user wants to do, is the end users 'choice', and not something that the developer/packager can make for him/her.

So why would you want to accept the new configuration file? For an application that you have installed but for which you haven't yet configured. In that case, you want the updated configuration file that is packaged with the updated application. Make sense?

What it boils down to: Users of Linux have a certain degree of responsibility to learn how their installed flavor of Linux works. They just have to, or they will always be at the mercy of their own ignorance.

PLEASE don't take the last statement as harsh criticism, as I don't mean it that way at all. All of use were at one time, 'new' to Linux. I was back in 2007, and I've experienced my share of hard knocks too.

[frankus333]

Thanks jglen490

That code shows I have the same version as you, except 32 bit, and no other entries. However, Muon shows 4 installed items related to network-manager (network-manager-pptp, network-manager-pptp-gnome, network-manager and network-manager-gnome), one of which is upgradeable (the third one, the one found with your code).

I can't find network-manager via the search in App Launcher. Is there another way to launch it, and would it give a different window from the other two I have already accessed?

Thanks Snowhog

No worries; no offence taken

This seems a complex situation which we don't have time or space to persue fully, so I am happy to live with my unknowns and accept the received wisdom of choosing to keep files, which I have no reliable way of knowing whether they have been modified by anything I, or the system, have done previously. (Other than the experimental Compare feature)

[frankus333]

G'day again folks

I am a little surprised that I have not had a reply that will tell me where the configuration files are and how to modify them. However, in looking at the dates on posts in this section, it appears there may not be a lot of interest and/or expertise regarding networking issues in this forum.

With nothing to lose, I opted to install nm-tray as suggested, along with the myriad of extra packages. It seems to cut off the connections temporarily when any of them is selected, and did not seem to provide any other adjustment options than the ones I have already accessed and experimented with.

Given the futility of trying to fix what I would have thought was a relatively simple misconfiguration problem, I have opted to wipe the drive and install a fresh copy of Kubuntu 18.04.1.

Cheers

[frankus333]

This problem has been Resolved rather than "Solved", via wiping of the drive to delete the upgraded installation, and a complete reinstall of a fresh copy of Kubuntu 18.04.1.

In hindsight this was probably the best plan anyway, and the upgrade from 14.04 to 18.04 was too big a jump and left behind too much of the old installation(s). The new installation seems tidier.