How to configure Nginx with free Let’s Encrypt SSL certificate on Debian or Ubuntu Linux

Let’s Encrypt is a free, automated, and open certificate authority for your website or any other projects. You can grab free TLS/SSL certificate including wildcard certificate to create encrypted HTTPS session for your site visitors. In this tutorial, I will explain how to use Let’s Encrypt to install a free SSL certificate for Nginx web server along with how to properly deploy Diffie-Hellman on your nginx server to get SSL labs A+ score on Debian and Ubuntu Linux server.