Let’s Encrypt is a new Certificate Authority (CA) that provides an easy way to obtain and install free TLS/SSL certificates, thereby enabling encrypted HTTPS on web servers. It simplifies the process by providing a software client, Certbot, that attempts to automate most (if not all) of the required steps. Currently, the entire process of obtaining and installing a certificate is fully automated on both Apache and Nginx web servers.
In this tutorial, we will show you how to use Certbot to obtain a free SSL certificate and use it with Nginx on Ubuntu 14.04 LTS. We will also show you how to automatically renew your SSL certificate.
We will use the default Nginx configuration file in this tutorial instead of a separate server block file. We recommend creating new Nginx server block files for each domain because it helps to avoid some common mistakes and maintains the default files as a fallback configuration as intended. If you want to set up SSL using server blocks instead, you can follow this Nginx server blocks with Let’s Encrypt tutorial.
Before following this tutorial, you’ll need a few things.
sudoprivileges. You can learn how to set up such a user account by following our initial server setup for Ubuntu 14.04 tutorial.
example.com, that domain must resolve to your server for the validation process to work. Our setup will use
www.example.comas the domain names, so both DNS records are required.
Once you have all of the prerequisites out of the way, let’s move on to installing Certbot, the Let’s Encrypt client software.
The first step to using Let’s Encrypt to obtain an SSL certificate is to install the
certbot software on your server. The Certbot developers maintain their own Ubuntu software repository with up-to-date versions of the software. Because Certbot is in such active development it’s worth using this repository to install a newer Certbot than provided by Ubuntu.
First, add the repository:
- sudo add-apt-repository ppa:certbot/certbot
You’ll need to press
ENTER to accept. Afterwards, update the package list to pick up the new repository’s package information:
- sudo apt-get update
And finally, install Certbot with
- sudo apt-get install python-certbot-nginx
certbot Let’s Encrypt client is now ready to use.
Certbot can automatically configure SSL for Nginx, but it needs to be able to find the correct
server block in your config. It does this by looking for a
server_name directive that matches the domain you’re requesting a certificate for. If you’re starting out with a fresh Nginx install, you can update the default config file:
- sudo nano /etc/nginx/sites-available/default
Find the existing
localhost with your domain name:
server_name example.com www.example.com;
Save the file and quit your editor. Verify the syntax of your configuration edits with:
- sudo nginx -t
If that runs with no errors, reload Nginx to load the new configuration:
- sudo service nginx reload
Certbot will now be able to find the correct
server block and update it. Now we’ll update our firewall to allow HTTPS traffic.
Certbot provides a variety of ways to obtain SSL certificates, through various plugins. The Nginx plugin will take care of reconfiguring Nginx and reloading the config whenever necessary:
- sudo certbot --nginx -d example.com -d www.example.com
certbot with the
--nginx plugin, using
-d to specify the names we’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:
OutputPlease 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 Nginx 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:
OutputIMPORTANT NOTES: - Congratulations! Your certificate and chain have been saved at /etc/letsencrypt/live/example.com/fullchain.pem. Your cert will expire on 2017-10-23. 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 now downloaded, installed, and configured. Try reloading your website using
https:// and notice your browser’s security indicator. It should represent 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 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 takes care of this for us by running ‘certbot renew’ twice a day via a systemd timer. On non-systemd distributions this functionality is provided by a script placed in
/etc/cron.d. This task runs twice a day and will renew any certificate that’s within thirty days of expiration.
To test the renewal process, you can do a dry run with
- sudo certbot renew --dry-run
If you see no errors, you’re all set. When necessary, Certbot will renew your certificates and reload Nginx 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.
In this tutorial we’ve installed the Let’s Encrypt client
certbot, downloaded SSL certificates for our domain, configured Nginx 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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