DNS resolution broken (because of hummingbird?)

[zurround 0]

last Thursday (31st of August), I installed hummingbird on a mini-PC with Ubuntu 23.04 as described on the download page. Using the generated OVPN file as argument, I started hummingbird successfully. And according to ipleak.net, everything looked fine. After a couple of hours, I noticed that hummingbird kept trying to reconnect. I stopped hummingbird, and at first glance, there was not network connection. It was late, so I shut the PC down.

The next day, I booted the mini-PC and noticed that DNS was broken. I could ping the router, ping the other PC connected to the router, but there was no name resolution. It appears I can ping an IP address like 5.196.64.52, but not www.airvpn.org.

At this point, I must admit my understanding of DNS resolution on Ubuntu is very limited. I don't know how to proceed to diagnose and solve the problem. My initial thought was that hummingbird did not shut down properly and left the system in a state where DNS is broken... except I don't know if that is even possible.

Could you point me to a resource with the steps to follow for addressing the problem? What do I need to look at, in what order? Do I need to disable something? Enable something? Reinstall something?

[OpenSourcerer 1441]

1 hour ago, zurround said:

Could you point me to a resource with the steps to follow for addressing the problem?

Try:

# hummingbird --recover-network

.

[zurround 0]

The output of the command is as follows:

Hummingbird - OpenVPN3 Client 1.3.0 - 1 June 2023

OpenVPN core 3.8.4 AirVPN linux x86_64 64-bit
Copyright (C) 2012-2022 OpenVPN Inc. All rights reserved.
OpenSSL 3.0.2 15 Mar 2022

It seems this program has properly exited in its last run and it has already
restored network settings on exit.
Network recovery is not needed.

so as far as hummingbird is concerned, everything is fine. Yet still no DNS.

What would you suggest for step #2?

[OpenSourcerer 1441]

4 hours ago, zurround said:

What would you suggest for step #2?

Relax, step 1 is still bugging out let's see what's configured first and how it plays out.

$ grep -e ^[^#] /etc/resolv.conf
$ cid=`nmcli c s --active | grep ethernet | cut -d" " -f3` && nmcli c s $cid|grep DNS

Which server does the system attempt to resolve with?

$ dig a in airvpn.org.

.

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$ cat /etc/resolv.conf
#
# Created by AirVPN. Do not edit.
#
# Your resolv.conf file is temporarily backed up in /etc/airvpn/resolv.conf.airvpnbackup
# To restore your resolv.conf file you need to log in as root
# and execute the below command from the shell:
#
# mv /etc/airvpn/resolv.conf.airvpnbackup /etc/resolv.conf
#

nameserver 10.9.26.1

interesting. So there is a backup...

$ tree /etc/airvpn/
/etc/airvpn/

0 directories, 0 files

or not. As for NetworkManager:

$ nmcli connection show Wired\ connection\ 1 | grep DNS
IP4.DNS[1]:                             192.168.0.1
IP6.DNS[1]:                             2a02:908:2:b::1
IP6.DNS[2]:                             2a02:908:2:a::1

Finally

$ dig a in airvpn.org.
;; communications error to 10.9.26.1#53: timed out
;; communications error to 10.9.26.1#53: timed out
;; communications error to 10.9.26.1#53: timed out

; <<>> DiG 9.18.12-0ubuntu0.22.04.2-Ubuntu <<>> a in airvpn.org.
;; global options: +cmd
;; no servers could be reached

which is to be expected?

So... /etc/resolv.conf is apparently borked.

[OpenSourcerer 1441]

2 hours ago, zurround said:

So... /etc/resolv.conf is apparently borked.

Yes, and I don't see why NetworkManager is not regenerating it. Did you at any point configure it to not touch DNS configuration? Because in case of that ethernet port resolv.conf should've been long regenerated by it by the time you rebooted, restarted NetworkManager or simply reconnected to that Wired connection 1.

Another possibility is that systemd-resolved is running and /etc/resolv.conf is actually a symlink. NetworkManager cedes configuration authority to that if it detects that. Can you check?

if [ -h /etc/resolv.conf ] ; then echo "symlink"; else echo "not a symlink";fi

.

[zurround 0]

systemd-resolved is running. After reading the manpage, I re-created the link to /run/systemd/resolve/stub-resolv.conf. One reboot later, my DNS works again.

Afterwards, I went through several rounds of starting hummingbird, letting it run for a while, stopping it. The link at /etc/resolv.conf was restored every time.

So that problem is solved.

I noticed that after a couple of hours, hummingbird would mention a "ERROR: KEEPALIVE_TIMEOUT", then repeat "EVENT: RECONNECTING" without ever succeeding. So I gave up on hummingbird and installed eddie-ui. I should have disabled the latency tests (it took a while), but otherwise, there were no errors.

Thanks for the feedback.

[OpenSourcerer 1441]

At this point, I'd like to mention the existence of the AirVPN suite comprising Bluetit, a D-Bus-controlled OpenVPN client, and Goldcrest, a CLI client for Bluetit. Hummingbird is not needed, then.
Otherwise, enjoy!