must install ssh, telnet not secure even password
=================================================
ssh -l root 99.999.999.99


install fail2ban
==================
sudo apt install fail2ban
systemctl status fail2ban.service
sudo systemctl enable fail2ban
sudo systemctl start fail2ban
sudo systemctl status fail2ban

automatically upgrade debian linux
===================================
sudo apt-get install unattended-upgrades apt-listchanges
sudo apt-get install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades


Install nginx
=============
sudo apt-get install nginx -y
sudo systemctl start nginx
sudo systemctl enable nginx

cat /etc/nginx/sites-enabled/default
cat /etc/nginx/sites-available/default


certbot ssl
============
sudo apt install snapd
sudo snap install core
sudo snap refresh core
sudo snap install --classic certbot
sudo ln -s /snap/bin/certbot /usr/bin/certbot
sudo certbot --nginx --agree-tos --redirect --email root@xxx.ca -d xxx.ca -d www.xxx.ca

upload files for static website
================================
/var/www/html

run process in background without hangingup or killing on exit
===============================================================
nohup bash-command &



to make it dynamic install php
=================================
sudo apt-get install php php-fpm php-curl php-cli php-zip php-mysql php-xml -y
php -v
sudo systemctl status php7.4-fpm
sudo nano /etc/nginx/sites-available/default
add index.php to index section in both 80/443 places
uncomment php section and apache section, leave the 9000 port section commented
must uncomment in both http 80 and https section 443
nginx -t
sudo service nginx reload
sudo chmod -R 777 /var/www/html
echo "<?php phpinfo(); ?>" >> /var/www/html/info.php
test but delete phpinfo file afterwards, since security risk
ls -la to see if have x for info.php
chmod 755 info.php or
recursively 
sudo chmod -R 755 /var/www/html
4=read
2=write
1=execute

sudo systemctl restart nginx


copy directory over ssh
=======================
scp -r /home/to/local/source user@ssh.example.com:/home/to/remote/destination 


download directory over ssh
===========================
scp -r user@ssh.example.com:/home/to/remote/source /path/to/local/destination