How to Setup Let’s Encrypt with Apache on Ubuntu Linux

How to install Certbot on Ubuntu Linux

Certbot is a command-line tool that automates acquiring and renewing Let’s Encrypt SSL certificates. While other tools exist, Certbot is efficient and user-friendly. To install it on Ubuntu, run the following commands:

sudo apt update
sudo apt install certbot

How to generate Let’s Encrypt certificates for Ubuntu Linux

Now that Certbot is installed, you can generate Let’s Encrypt SSL certificates on Ubuntu Linux.

We’ll use the Webroot plugin to automate certificate generation and renewal. This plugin checks a specific directory, `/well-known/acme-challenge` at your web server’s root, to confirm that the Certbot server can access your domain.

We will create a challenge/response Alias to allow Let’s Encrypt to validate the server for which the certificates were generated. To do that, run the commands below.

To do that, run the commands below to create a configuration file called well-known.conf in the /etc/apache2/conf-available directory. This directory contains all configurations you want to use with the Apache web server. All config files are automatically included in Apache’s main configuration file.

sudo nano /etc/apache2/conf-available/well-known.conf

Then copy and paste the content below into the file and save it.

Alias /.well-known/acme-challenge/ "/var/www/html/.well-known/acme-challenge/"

<Directory "/var/www/html/">
    AllowOverride None
    Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
    Require method GET POST OPTIONS
</Directory>

The configuration file above allows Let’s Encrypt to validate the web server using the Webroot plugin.

Before SSL and HTTPS, a typical Apache VirtualHost file should look like the one below.

<VirtualHost *:80>
  ServerName example.com
  ServerAlias www.example.com
  ServerAdmin admin@example.com
  DocumentRoot /var/www/example.com
    
  <Directory /var/www/example.com/>
       Options FollowSymlinks
       AllowOverride All
       Require all granted
  </Directory>

       ErrorLog ${APACHE_LOG_DIR}/error.log
       CustomLog ${APACHE_LOG_DIR}/access.log combined
    
</VirtualHost>

How to generate Dh (Diffie-Hellman) Group

Diffie–Hellman key exchange (DH) is a method for securely exchanging cryptographic keys. In most SSL configurations, you’ll want to generate a strong Diffie-Hellman key group.

Run the commands below to generate a key in the /etc/ssl/cert directory on Ubuntu Linux.

sudo openssl dhparam -out /etc/ssl/certs/dhparam.pem 2048

How to obtain Let’s Encrypt certificates on Ubuntu Linux

At this point, you should be ready to obtain a free certificate from Let’s Encrypt. Before you generate your free certificates, run the commands below to enable these Apache modules for SSL, Headers, and HTTP version 2.

sudo a2enmod ssl
sudo a2enmod headers
sudo a2enmod http2

Also, enable the configuration files we created in the conf-available directory.

sudo a2enconf well-known.conf

Once complete, reload Apache by running the commands below.

sudo systemctl reload apache2

Now you’re ready to generate Let’s Encrypt SSL certificates. Run the commands below, replacing example.com with your domain to generate Let’s Encrypt SSL certificates.

sudo certbot certonly --agree-tos --email admin@example.com --webroot -w /var/www/html -d example.com -d www.example.com

A successful certificate generation message will look similar to the one below:

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/example.com/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/example.com/privkey.pem
   Your cert will expire on 2021-09-07. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"
 - Your account credentials have been saved in your Certbot
   configuration directory at /etc/letsencrypt. You should make a
   secure backup of this folder now. This configuration directory will
   also contain certificates and private keys obtained by Certbot so
   making regular backups of this folder is ideal.
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

You can now use the certificate and key in your Apache VirtualHost configurations.

Your new configuration, after adding recommended SSL settings, should look similar to the one below:

<VirtualHost *:80>
  ServerName example.com
  ServerAlias www.example.com

  Redirect permanent / https://example.com/
</VirtualHost>

<VirtualHost *:443>
  ServerName example.com
  ServerAlias www.example.com
  DocumentRoot /var/www/example.com

  Protocols h2 http:/1.1

  <If "%{HTTP_HOST} == 'www.example.com'">
    Redirect permanent / https://example.com/
  </If>
  
  ErrorLog ${APACHE_LOG_DIR}/example.com-error.log
  CustomLog ${APACHE_LOG_DIR}/example.com-access.log combined

  SSLEngine On
  SSLCertificateFile /etc/letsencrypt/live/example.com/fullchain.pem
  SSLCertificateKeyFile /etc/letsencrypt/live/example.com/privkey.pem
  SSLOpenSSLConfCmd DHParameters "/etc/ssl/certs/dhparam.pem"
  
  SSLCipherSuite ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384

  SSLProtocol All -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
  SSLCompression off
  SSLUseStapling on

  Header always set Strict-Transport-Security "max-age=63072000"

  <Directory /var/www/example.com/>
       Options FollowSymlinks
       AllowOverride All
       Require all granted
  </Directory>
 
</VirtualHost>

Make changes to the configurations above to suit your environment. However, the settings above should work in most Apache environments.

How to auto-renew Let’s Encrypt certificates

Once the certificate is generated, you can set up a process to renew the certificates automatically. By default, it expires in 90 days. Setting up a process so you don’t have to remember to renew is the best option.

The certbot package creates a cronjob and a system timer to renew the certificates automatically before expiration. The timer will automatically renew the certificates 30 days before their expiration.

The crontab file is created at the location below.

cat /etc/cron.d/certbot

If you make changes to the file, you should save and exit.

You can now use the certificate and key files above to enable HTTPS in your Apache configurations.

Conclusion:

• Let’s Encrypt provides a free and automated way to secure your website with SSL certificates.
• Setting up Let’s Encrypt on Ubuntu with Apache is straightforward and can be completed by following the above steps.
• Regularly renewing your SSL certificate is crucial, and Certbot automates this process.
• Implementing SSL not only enhances security but also improves the credibility of your website.
• Let’s Encrypt saves you on costs typically associated with purchasing SSL certificates while ensuring your site is secure.