I've installed Free Radius following these steps:
sudo apt install freeradius freeradius-config
sudo sed -i '1s/^/steve Cleartext-Password := "testing"\n/' /etc/freeradius/3.0/users
sudo systemctl stop freeradius.service
sudo usermod -a -G ssl-cert freerad
sudo freeradius -X
sudo chmod 744 /usr/local/etc/raddb/dictionary
radtest -x steve testing 127.0.0.1 10 testing123
The last command run (number 7, radtest) fails with this output:
$ radtest -x steve testing 127.0.0.1 10 testing123
radclient:: Unknown attribute "User-Name" requires a hex string, not "steve"
radclient: Nothing to send.
I have googled for this, and the best I can find, is a mailing list (https://freeradius-users.freeradius.narkive.com/pFaFTRpq/beginner-need-help) that was saved on multiple sites. The user has the same problem as me, but gets destracted and tries to fix the rest of his issues without ever coming back to this one. It's a very frustrating read, and I highly discourage you from it.
How can I fix my setup, so I can test freeradius?