Ubuntu falsely reports "No Internet"

[Brompot]

A number of Ubuntu parts report "No Internet" which is obviously untrue as I'm filling out this bug report from that very machine. E.G., trying to add an online account is impossible and software updater won't show me the information of the packages it wants to update. Even though software updater claims there is no internet, it then goes on and updates the packages from the Internet. So something is seriously wrong with Internet presence detection, and it prevents me from doing a number of things that should just work.

It happens in many places, so I can't specify a package.

Description: Ubuntu 22.04.3 LTS
Release: 22.04

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Libera.chat.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/2033099/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Bug reporting is mostly about finding & fixing problems thus preventing future users from hitting the same bug.

I suspect a Support site would be more appropriate, eg. https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709

( You've provided no system details; no clues as to if this is Ubuntu 22.04 LTS Server, Ubuntu 22.04 Desktop, or a flavor of 22.04.. and what upgrades were applied. It is possible that you're on a corporate/educational network that is filtering specific traffic thus some traffic gets through & your issue is not bugs, but support related to your networking environment stopping some traffic (thus offline messages) etc. No details were provided due to online reporting, rather than `ubuntu-bug` type reporting on the actual box where the issue occurred )

[Brompot (ubuntubugz-vdnberg)]

I ran the exact command line the error report asked for when I entered the bug on the website. That's only 2 lines, I know. I'm sorry, but this is what the web page asks for. ubuntu-bug refused to work because it thinks it has no internet connection.

I'm aware of what a bug is. I'm a software developer, among other things.

The stuff on the support sites I've already looked at. No Joy.

Consider the software updater. It first fetches the package metadata from Internet. It then shows me the packages that need updating, but refuses to show me the package details (what was fixed etc) claiming it has no network connection. Then it goes on to update those very packages from the Internet. In my book that counts as a bug. Because it's not limited to just the software updater I chose to report the general issue rather than a software updater bug.

As for my system, it was installed from Unbuntu 20.04 desktop in 2021, an ISO downloaded from the Ubuntu site. I upgraded it to 22.04 using do-release-upgrade. Additions are chrome, opera, graphics drivers, libre office from libre office PPA, mysql repository (for the workbench only), nextcloud client, remmina from remmina, teams previes, and yubbico repository.

The problem has been there from the start, but I have not gotten round to reporting it earlier.

The machine is an AMD Ryzen 9 5950X with 128GB DDR4-3600 CL16, an Asus RTX4090 and a Samsung EVO 970 2TB as SSD. The MB is an MSI MPG Edge WiFi.

The connection is an ethernet connection, not WiFi.

I've checked the network traffic, there are no failed connections in a period where the issue shows itself. The firewall has two rules outgoing for this segment:

all->all any->25/tcp reject
all->all any->any allow

I doubt SMTP is used for connection checking and I see no connection attempts on 25/tcp
If I boot my machine in Windows, no issue. I'm aware Windows has a different mechanism for connection checking
If I connect the machine through my phone (5G) with a USB ethernet dongle on the phone the problem persists

I've thoroughly ruled out connectivity as the issue.

It may have something to with the fact that I use ifupdown for network configuration. When I first installed the machine netplan did not yet support all that I need in my network config. The ubuntu help site recommended falling back to ifupdown in that situation, so I did. I was unable to get NetworkManager running as needed either. But as ifupdown is formally supported by Ubuntu, other components should be able to work with it properly.

[Brompot (ubuntubugz-vdnberg)]

I've dug deeper. Some GUI parts (such as software updater and Online Accounts in setup) rely on NetworkManager to determine if there is an Internet connection. NetworkManager checks if it manages any interfaces that are up, and if not, reports there is no Internet.

When NetworkManager is not the one managing the interfaces, as in my case, NetworkManager erroneously reports the lack of Internet. The internet connection is fine, it's just not managed by NetworkManager.

IMO this is a serious bug that needs fixing. For Software Updater it's even worse as sometimes this component relies on NetworkManager and sometimes it does not, all in the same update run. Relying on different mechanisms for the same thing (is there Internet?) in the same component is a serious flaw IMO.

It's not just one package, it's how a group of packages works together.

There is a NetworkManager plugin for ifupdown (this emulates ifupdown, it does not use the real ifupdown), but that's incomplete. It ignores pre-up, post-up, pre-down and post-down, which were the whole reason for avoiding netplan/NetworkManager in the first place.