Knowledgebase

Introduction

Let's Encrypt is an automated, open certificate authority that offers free TLS/SSL certificates for the public's benefit. The service is provided by the Internet Security Research Group (ISRG). This tutorial shows how to install a Let's Encrypt SSL certificate on an Ubuntu 20.04 server with either Apache or Nginx using the Certbot installation wizard. After completing this tutorial, the server will have a valid certificate and redirect all HTTP requests to HTTPS.

Prerequisites

This tutorial assumes that you have deployed a Rcs Ubuntu server with Apache or Nginx, have a domain name pointing to your server IP address, and you are logged in as root.

1. Install Certbot

The recommended installation method for Certbot is with Snap.

1. Verify snapd is up to date.

    $ sudo snap install core; sudo snap refresh core

2. Remove certbot-auto and any Certbot OS packages.

    $ sudo apt-get remove certbot

3. Install Certbot with Snap.

    $ sudo snap install --classic certbot

4. Link Certbot to /usr/bin.

    $ sudo ln -s /snap/bin/certbot /usr/bin/certbot

2. Install Certificate

Run certbot to install the certificate. Full examples are below, here are descriptions of the command line options:

• --apache: Use the Apache web server
• --nginx: Use the nginx web server
• --redirect: Redirect all HTTP requests to HTTPS.
• -d example.com -d www.example.com: Install a multiple domain (SAN) certificate. You may use up to 100 -d domain entries.
• -m admin@example.com: The notification email address for this certificate.
• --agree-tos: Agree to the terms of service.

Use certbot --help for more information. See the Certbot FAQ for more information about SAN certificates.

Example: Apache

Run Certbot for Apache.

# certbot --apache --redirect -d example.com -d www.example.com -m admin@example.com --agree-tos

Example: Nginx

1. Before running Certbot, make sure server_name is set properly. Edit your Nginx configuration:

    # nano /etc/nginx/conf.d/default.conf

2. Update server_name to include your domain name.

    server {
        server_name  example.com www.example.com;

3. Save and exit the file.

4. Run Certbot for Nginx.

    # certbot --nginx --redirect -d example.com -d www.example.com -m admin@example.com --agree-tos

3. Verify Automatic Renewal

Let's Encrypt certificates are valid for 90 days. The Certbot wizard updates the systemd timers and crontab to automatically renew your certificate.

1. Verify the timer is active.

    # systemctl list-timers | grep 'certbot\|ACTIVATES'

2. Verify the crontab entry exists.

    # ls -l /etc/cron.d/certbot

3. Verify the renewal process works with a dry run.

    # certbot renew --dry-run

Summary

Installing a free Let's Encrypt certificate is simple with Certbot. For more information, see the official Certbot installation documentation.