sudo apt-get install freeradius

sudo vim /etc/freeradius/users
test Cleartext-Password := "5678"

sudo vim /etc/freeradius/clients.conf
client 192.168.0.0/16 {
secret = aaaa
shortname = privat-network-1
}

sudo service freeradius restart

radtest test 5678 localhost 0 testing123