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Topic: Loopback device (lo) suddenly appeared after update (Read 821 times) previous topic - next topic
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Loopback device (lo) suddenly appeared after update

I updated, rebooted and noticed, alongside my normal Ethernet connection, a new connection: lo

https://imgur.com/AiClbBm

ip addr
Code: [Select]
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 brd 127.255.255.255 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever

After googling, I found that it's a loopback device. https://unix.stackexchange.com/questions/148735/what-does-eno1-and-lo-mean

I don't entirely understand what that is, but more importantly, why has it suddenly appeared?

Re: Loopback device (lo) suddenly appeared after update

Reply #1 –
Although not absolutely essential, the loopback device is used by many programs and services in Linux (Xorg included), as it allows inter-process communication (sort of, more like localized client/server communication). It should have been enabled by default from the very beginning though, post your /etc/os-release.

Re: Loopback device (lo) suddenly appeared after update

Reply #2 –
Quote from: nous – on
Although not absolutely essential, the loopback device is used by many programs and services in Linux (Xorg included), as it allows inter-process communication (sort of, more like localized client/server communication). It should have been enabled by default from the very beginning though, post your /etc/os-release.


/etc/os-release:
Code: [Select]
NAME="Artix Linux"
PRETTY_NAME="Artix Linux"
ID=artix
BUILD_ID=rolling
ANSI_COLOR="0;36"
HOME_URL="https://www.artixlinux.org/"
DOCUMENTATION_URL="https://wiki.artixlinux.org/"
SUPPORT_URL="https://forum.artixlinux.org/"
BUG_REPORT_URL="https://bugs.artixlinux.org/"
PRIVACY_POLICY_URL="https://terms.artixlinux.org/docs/privacy-policy/"
LOGO=artixlinux-logo

My understanding is that it's something that works in the background on all systems, but I've never seen it before in any previous installs, of Artix or any other distro. Now it just appeared right after I updated (the update contained a kernel update, if that makes any difference).

Also, I just remembered, about a week ago I installed DWM alongside my current Plasma install. Could that maybe have something to do with it?  
 

Re: Loopback device (lo) suddenly appeared after update

Reply #3 –
You've always had the (lo) loopback interface.
For some reason the Plasma NetworkManager applet has started showing it.
I would expect that NetworkManager, the applet, or both, have been updated and something changed (maybe a bug or maybe it's intentional?). Either in the programs themselves or in a new config file that has been stored as a .pacnew file which would need using.
This is purely a guess. I don't use NetworkManager.

It will do no harm to leave it showing but if it bothers you and you want to hide it then this might help
https://wiki.archlinux.org/title/NetworkManager#Ignore_specific_devices
Specifically:
/etc/NetworkManager/conf.d/unmanaged.conf
Code: [Select]
[keyfile]
unmanaged-devices=interface-name:lo
Worth a try.

Re: Loopback device (lo) suddenly appeared after update

Reply #4 –
Quote from: gripped – on
You've always had the (lo) loopback interface.
For some reason the Plasma NetworkManager applet has started showing it.
I would expect that NetworkManager, the applet, or both, have been updated and something changed (maybe a bug or maybe it's intentional?). Either in the programs themselves or in a new config file that has been stored as a .pacnew file which would need using.
This is purely a guess. I don't use NetworkManager.

It will do no harm to leave it showing but if it bothers you and you want to hide it then this might help
https://wiki.archlinux.org/title/NetworkManager#Ignore_specific_devices
Specifically:
/etc/NetworkManager/conf.d/unmanaged.conf
Code: [Select]
[keyfile]
unmanaged-devices=interface-name:lo
Worth a try.
The fact that it's visible doesn't bother me, it's just that seeing it suddenly pop up out of nowhere spooked me a bit, being a network component and all. Could it's appearance cause, or be caused by some possible security concern?

Re: Loopback device (lo) suddenly appeared after update

Reply #6 –
Same issue here. I was concerned but it doesn't look like an issue.

Re: Loopback device (lo) suddenly appeared after update

Reply #7 –
Marking this as solved since, although anomalous, the device's appearance doesn't seem to be harmful. Thank you to all who commented.