This tutorial will show you how to install and secure a Nginx web server on Debian 9 with a TLS certificate issued for free by the Let’s Encrypt Certificate Authority. Furthermore, we will configure automatic renewal of Lets’ Encrypt TLS certificates using a cron job before the certificates expire.
TLS, also known as Transport Layer Security, is a network protocol that uses SSL certificates to encrypt the network traffic which flows between a server and a client, or between a web server, such as Nginx server, and a browser. All data exchanged in between these two entities is secured and the connection cannot be decrypted even if it is intercepted using a technique such as by a man in the middle attack or packet sniffing. The certbot package software is the official client utility provided by Let’s Encrypt CA that can be used in the process of generating and downloading free Let’s Encrypt certificates in Debian.
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