Mysterious loopback network just appeared

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1

Sometime in the past 2 days (not sure when exactly) a loopback network appeared in the KDE network settings. I am not sure exactly what triggered it. I do see the network being used, though I haven’t found a pattern for when that happens.

image

$ ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
(other networks not included)
3 Likes
2

Apparently, this may be a new feature:

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3

This would make sense, as it was added in 1.42 which was recently pushed to my branch (testing). If it now treats loopbacks as a normal network, then it would show up normally in Plasma’s plasma-nm applet which is where I saw it. Before this update, loopbacks were special so they were hidden(?).

4

It’s a device you always have, it’s the one that answers if you call localhost.
Why it should be configurable by NetworkManager confuses me. Anyone who ever had the need to configure lo did so already, now this changes, evidently by this thread, confuses more people than in helps.

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5

They could have made it an option in the applet for it to be shown I guess (and not shown by default).

6

You can hide it by excluding the device from Network Manager.

Create a file: /etc/NetworkManager/conf.d/unmanaged.conf with these lines:

[keyfile]
unmanaged-devices=interface-name:lo

After saving, run sudo nmcli general reload

(most of this comes from the ArchWiki)

4 Likes
7

It’s not bothering anything but just clicked on the network applet and mine shows wired and lo so I guess it came with the update.

8
1 Like
9

I found this today:
The Networks widget will no longer unnecessarily show the loopback interface when using NetworkManager 1.42 (David Redondo, Plasma 5.27.1. Link)

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