Because my application is handling login information, I would like to encrypt the data sent between the visitor and the server. Luckily for me there is . free service called Let’s Encrypt which is a Certificate Authority (CA) that provides us an easy way to obtain and install a free TLS / SSL certificate.

With a TLS / SSL certificate we can enale HTTPS on our web server. To simplify the process I will be using software called Certobot, that attempts to automate most of the required steps (if not all of them actually). At the moment the process of installing a certificate on Ubuntu using Apache or Nginx is fully automated.

In this article i will describe and show to to use Certbot to obtain a free SSL certificate for Apache on Ubuntu, since my application is hosted within that environment.

Note: I will be using a separate Apache virtual host file instead of the default one. If you would like to follow along, i would recommend you to create new Apache virtual host files for each of your domains. This can help you avoid mistakes within the process and makes it easier for you to fallback on the default configuration.

Prerequisites to install a certificate

To follow along with me, you will need:

  • One Ubuntu 18.04 server set up by following this initial server setup for Ubuntu 18.04 tutorial, including a sudo non-root user and a firewall.
  • A fully registered domain name. This tutorial will use example.com throughout. You can purchase a domain name on Namecheap, get one for free on Freenom, or use the domain registrar of your choice.
  • Both of the following DNS records set up for your server. You can follow this introduction to DigitalOcean DNS for details on how to add them.
    • An A record for yourwebsite.com in your DNS Server pointing to your servers public IP address.
    • An A record for www.yourwebsite.com in your DNS Server pointing to your servers public IP address.
  • Apache installed by following How To Install A LAMP stack on Ubuntu 18.04. Be sure that you have a virtual host file for your domain. This tutorial will use /etc/apache2/sites-available/example.com.conf as an example.

Step 1 — Installing Certbot

The first step to using Let’s Encrypt to obtain an SSL certificate is to install the Certbot software on your server.

Certbot is in very active development, so the Certbot packages provided by Ubuntu tend to be outdated. However, the Certbot developers maintain a Ubuntu software repository with up-to-date versions, so we’ll use that repository instead.

First, add the repository using the package manager in Ubuntu:

sudo add-apt-repository ppa:certbot/certbot

You’ll need to press ENTER to accept the installation for Certbot on Ubuntu.

Install Certbot’s Apache package with APT:

sudo apt install python-certbot-apache

Certbot is now ready to use, but in order for it to configure SSL for Apache, we need to verify some of Apache’s configuration files first.

Step 2 — Set Up the SSL Certificate

Certbot needs to be able to find the correct virtual host in your Apache configuration for it to automatically configure SSL. Specifically, it does this by looking for a ServerName directive that matches the domain you request a certificate for.

If you have set up Apache as I have done using virtual host file, you should have a VirtualHost block for your domain at /etc/apache2/sites-available/example.com.conf with the ServerName directive already set appropriately.

Let’s check it by opening the virtual host file for your domain using nano (editor) or your favorite text editor – doesn’t matter:

sudo nano /etc/apache2/sites-available/example.com.conf

Find the existing ServerName line. It should look like this:/etc/apache2/sites-available/example.com.conf

...
ServerName example.com;
...

If it does, exit your editor and move on to the next step.

If it doesn’t, update it to match. Then save the file, quit your editor, and verify the syntax of your configuration edits:

sudo apache2ctl configtest

If you get an error, reopen the virtual host file and check for any typos or missing characters. Once your configuration file’s syntax is correct, reload Apache to load the new configuration:

sudo systemctl reload apache2

Certbot can now find the correct VirtualHost block and update it.

Next, let’s update the firewall to allow HTTPS traffic.

Step 3 — Allowing HTTPS Through the Firewall

If you have the UFW firewall enabled, as I always recommended, you’ll need to adjust the settings to allow for HTTPS traffic. Luckily, Apache registers a few profiles with UFW upon the installation.

You can see the current setting by typing the following command in your terminal:

sudo ufw status

It will probably look like this, meaning that only HTTP traffic is allowed to the web server:

OutputStatus: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Apache                     ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Apache (v6)                ALLOW       Anywhere (v6)

To additionally let in HTTPS traffic, allow the Apache Full profile and delete the redundant Apache profile allowance:

sudo ufw allow 'Apache Full'
sudo ufw delete allow 'Apache'

Your status should now look like this:

sudo ufw status
OutputStatus: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Apache Full                ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Apache Full (v6)           ALLOW       Anywhere (v6)        

Next, let’s run Certbot and fetch our certificates.

Step 4 — Obtaining an SSL Certificate

Certbot provides a variety of ways to obtain SSL certificates through plugins. The Apache plugin will take care of reconfiguring Apache and reloading the config whenever necessary. To use this plugin, type the following:

sudo certbot --apache -d example.com -d www.example.com

This runs Certbot with the –apache plugin, using -d to specify the names you’d like the certificate to be valid for.

If this is your first time running certbot, you will be prompted to enter an email address and agree to the terms of service. After doing so, certbot will communicate with the Let’s Encrypt server, then run a challenge to verify that you control the domain you’re requesting a certificate for.

If that’s successful, certbot will ask how you’d like to configure your HTTPS settings:

Output Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
-------------------------------------------------------------------------------
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel):

Select your choice then hit ENTER. The configuration will be updated, and Apache will reload to pick up the new settings. Certbot will wrap up with a message telling you the process was successful and where your certificates are stored:

Output 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 2018-07-23. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot again
   with the "certonly" option. 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

Your certificates are downloaded, installed, and loaded. Try reloading your website using https:// and notice your browser’s security indicator. It should indicate that the site is properly secured, usually with a green lock icon. If you test your server using the SSL Labs Server Test, it will get an A grade.

Let’s finish by testing the renewal process.

Step 5 — Verifying Certbot Auto-Renewal

Let’s Encrypt’s certificates are only valid for ninety days. This is to encourage users to automate their certificate renewal process. The certbot package we installed earlier, takes care of this for us by adding a renew script to /etc/cron.d. This script runs twice a day and will automatically renew any certificate that’s within thirty days of expiration.

To test the renewal process, you can do a dry run with certbot:

sudo certbot renew --dry-run

If you see no errors, you’re all set. When necessary, Certbot will renew your certificates and reload Apache to pick up the changes. If the automated renewal process ever fails, Let’s Encrypt will send a message to the email you specified, warning you when your certificate is about to expire.

Conclusion

In this tutorial, you installed the Let’s Encrypt client certbot, downloaded SSL certificates for your domain, configured Apache to use these certificates, and set up automatic certificate renewal. If you have further questions about using Certbot, their documentation is a good place to start.

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