How to enable new DNS over TLSv1.2 encrypted communications in Ubuntu 18.04 64-bit using a bash shell script

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# enable new DNS over TLSv1.2 encrypted communications
# in Ubuntu 18.04 64-bit using a bash shell script
# Source: https://www.linuxbabe.com/ubuntu/ubuntu-stubby-dns-over-tls
sudo apt purge unbound avahi-daemon
LogTime=$(date '+%Y-%m-%d_%Hh%Mm%Ss')

cp /etc/resolv.conf $HOME/resolv.conf_$LogTime
cp /etc/nsswitch.conf $HOME/nsswitch.conf_$LogTime
cp /etc/systemd/resolved.conf $HOME/resolved.conf_$LogTime
cp /etc/network/interfaces $HOME/interfaces_$LogTime

sudo service resolvconf stop
sudo update-rc.d resolvconf remove

sudo apt install stubby
systemctl status stubby
sudo netstat -lnptu | grep stubby
sudo netstat -lnptu | grep systemd-resolve

cp /etc/resolv.conf /tmp/resolv.conf
grep -v nameserver /tmp/resolv.conf > /tmp/resolv.conf.1
echo 'nameserver 127.0.0.1' >> /tmp/resolv.conf.1
# echo 'nameserver 2620:fe::fe' >> /tmp/resolv.conf.1
echo 'domain dnsknowledge.com' >> /tmp/resolv.conf.1
echo 'options rotate' >> /tmp/resolv.conf.1
sudo cp /tmp/resolv.conf.1 /etc/resolv.conf
sudo service resolvconf start

# configure DNS server on Ubuntu 18.04 LTS:
cp /etc/network/interfaces /tmp/interfaces
grep -v nameservers /tmp/interfaces > /tmp/interfaces.1
grep -v search /tmp/interfaces.1 > /tmp/interfaces.2
grep -v options /tmp/interfaces.2 > /tmp/interfaces.3
#echo 'dns-nameservers 9.9.9.9 2620:fe::fe' >> /tmp/interfaces.3
echo 'dns-nameservers 127.0.0.1' >> /tmp/interfaces.3
echo 'dns-search dnsknowledge.com' >> /tmp/interfaces.3
echo 'dns-options rotate' >> /tmp/interfaces.3
sudo cp /tmp/interfaces.3 /etc/network/interfaces

# enable systemd caching DNS resolver
rm /tmp/nsswitch.conf
rm /tmp/nsswitch.conf.1
cp /etc/nsswitch.conf /tmp/nsswitch.conf
grep -v hosts /tmp/nsswitch.conf > /tmp/nsswitch.conf.1
# dns must be mentioned in next line, or else wget does not work
echo 'hosts: files mdns4_minimal [NOTFOUND=return] resolv dns myhostname mymachines' >> /tmp/nsswitch.conf.1
sudo cp /tmp/nsswitch.conf.1 /etc/nsswitch.conf

# set DNS server to 127.0.0.1
rm /tmp/resolved.conf
rm /tmp/resolved.conf.1
cp /etc/systemd/resolved.conf /tmp/resolved.conf
grep -v DNS /tmp/resolved.conf > /tmp/resolved.conf.1
#echo 'DNS=9.9.9.9' >> /tmp/resolved.conf.1
echo 'DNS=127.0.0.1' >> /tmp/resolved.conf.1
echo 'DNSSEC=yes' >> /tmp/resolved.conf.1
sudo cp /tmp/resolved.conf.1 /etc/systemd/resolved.conf
sudo systemd-resolve --flush-caches
sudo systemctl restart systemd-resolved
sudo systemd-resolve --flush-caches
sudo systemd-resolve --status

# It is probably also necessary to manually set
# the DNS server to 127.0.0.1 in the router's configuration
# and in the NetworkManager GUI

# Then reboot your PC to enable new DNS over TLSv1.2 encrypted communications
# Use wireshark application and capture encrypted DNS packages on port 853 
# There should be no more DNS handshakes on port 53 and only encrypted DNS handshakes on port 853

# Test DNSSEC validation using dig command-line tool
# See: https://docs.menandmice.com/display/MM/How+to+test+DNSSEC+validation
dig pir.org +dnssec +multi
host dnsknowledge.com

# To get similar functionality on iOS: install "DNSCloak" application
# To get similar functionality on Android: install "Intra" application