https://icing.github.io/mod_h2/howto.html
https://mozilla.github.io/server-side-tls/ssl-config-generator/
https://hstspreload.org/
https://michael.lustfield.net/nginx/getting-a-perfect-ssl-labs-score
https://www.ssllabs.com/ssltest/analyze.html
https://certbot.eff.org/
https://github.com/Neilpang/le
https://memo-linux.com/configurer-le-serveur-web-nginx-en-https-avec-letsencrypt-sous-debian-jessie/
https://letsencrypt.org/
http://www.khanio.com/posts/2013/04/20/rapidssl-nginx-web-server-setup/