What I have tried:
I followed this tutorial for Ubuntu:
And in the ''Testing'' section they suggest to run from the terminal the command:
sudo tcpdump -i 'port 853'
In my system this command...
I want to edit the file
which contains the following:
# This file is part of systemd.
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation...