// Tutorial //

How To Secure Nginx with Let's Encrypt on Ubuntu 20.04

Published on May 20, 2020 · Updated on March 1, 2021
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By Brian Boucheron
Developer and author at DigitalOcean.
How To Secure Nginx with Let's Encrypt on Ubuntu 20.04
Not using Ubuntu 20.04?Choose a different version or distribution.

Introduction

Let’s Encrypt is a 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.

In this tutorial, you will use Certbot to obtain a free SSL certificate for Nginx on Ubuntu 20.04 and set up your certificate to renew automatically.

This tutorial will use a separate Nginx server configuration file instead of the default file. We recommend creating new Nginx server block files for each domain because it helps to avoid common mistakes and maintains the default files as a fallback configuration.

Prerequisites

To follow this tutorial, you will need:

  • One Ubuntu 20.04 server set up by following this initial server setup for Ubuntu 20.04 tutorial, including a sudo-enabled non-root user and a firewall.

  • A registered domain name. This tutorial will use example.com throughout. You can purchase a domain name from Namecheap, get one for free with Freenom, or use the domain registrar of your choice.

  • Both of the following DNS records set up for your server. If you are using DigitalOcean, please see our DNS documentation for details on how to add them.

    • An A record with example.com pointing to your server’s public IP address.
    • An A record with www.example.com pointing to your server’s public IP address.
  • Nginx installed by following How To Install Nginx on Ubuntu 20.04. Be sure that you have a server block for your domain. This tutorial will use /etc/nginx/sites-available/example.com 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.

Install Certbot and it’s Nginx plugin with apt:

  1. sudo apt install certbot python3-certbot-nginx

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

Step 2 — Confirming Nginx’s Configuration

Certbot needs to be able to find the correct server block in your Nginx configuration for it to be able to automatically configure SSL. Specifically, it does this by looking for a server_name directive that matches the domain you request a certificate for.

If you followed the server block set up step in the Nginx installation tutorial, you should have a server block for your domain at /etc/nginx/sites-available/example.com with the server_name directive already set appropriately.

To check, open the configuration file for your domain using nano or your favorite text editor:

  1. sudo nano /etc/nginx/sites-available/example.com

Find the existing server_name line. It should look like this:

/etc/nginx/sites-available/example.com
...
server_name example.com www.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:

  1. sudo nginx -t

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

  1. sudo systemctl reload nginx

Certbot can now find the correct server block and update it automatically.

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 recommended by the prerequisite guides, you’ll need to adjust the settings to allow for HTTPS traffic. Luckily, Nginx registers a few profiles with ufw upon installation.

You can see the current setting by typing:

  1. sudo ufw status

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

Output
Status: active To Action From -- ------ ---- OpenSSH ALLOW Anywhere Nginx HTTP ALLOW Anywhere OpenSSH (v6) ALLOW Anywhere (v6) Nginx HTTP (v6) ALLOW Anywhere (v6)

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

  1. sudo ufw allow 'Nginx Full'
  2. sudo ufw delete allow 'Nginx HTTP'

Your status should now look like this:

  1. sudo ufw status
Output
Status: active To Action From -- ------ ---- OpenSSH ALLOW Anywhere Nginx Full ALLOW Anywhere OpenSSH (v6) ALLOW Anywhere (v6) Nginx 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 Nginx plugin will take care of reconfiguring Nginx and reloading the config whenever necessary. To use this plugin, type the following:

  1. sudo certbot --nginx -d example.com -d www.example.com

This runs certbot with the --nginx plugin, using -d to specify the domain 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.

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 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:

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 2020-08-18. 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" - 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 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 takes care of this for us by adding a systemd timer that will run twice a day and automatically renew any certificate that’s within thirty days of expiration.

You can query the status of the timer with systemctl:

  1. sudo systemctl status certbot.timer
Output
● certbot.timer - Run certbot twice daily Loaded: loaded (/lib/systemd/system/certbot.timer; enabled; vendor preset: enabled) Active: active (waiting) since Mon 2020-05-04 20:04:36 UTC; 2 weeks 1 days ago Trigger: Thu 2020-05-21 05:22:32 UTC; 9h left Triggers: ● certbot.service

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

  1. 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.

Conclusion

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


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Developer and author at DigitalOcean.

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10 Comments

After upgrading my droplet from 18.04 to 20.04, I didn’t know it, but auto-renew silently broke.

The tutorial showed me how to confirm it was broken:

$ sudo systemctl status certbot.timer
● certbot.timer
Loaded: masked (Reason: Unit certbot.timer is masked.)
Active: inactive (dead)
Trigger: n/a

But gave no clue what to do next.

I’d never heard of a system daemon being masked, but tried to unmask it. After unmasking I tried to run certbot, but it was not found. I tried to re-install, but it was unavailable.

Finally I learned, in https://askubuntu.com/questions/1278936/install-certbot-on-ubuntu-20-04 that the install instructions in this tutorial have been superceded for 20.04.

sudo snap install certbot --classic

got certbot re-installed.

From there, re-running certbot seems to have refreshed my certs.

Please update these instructions:

Correct the installation information.

Provide troubleshooting information so that others can figure out for themselves what to do when certbot gets deleted across a system upgrade.

This did not quite work for me, but I found a workaround.

After some steps, the certbot checks its work with a “http-01 challenge”. With ufw set to block HTTP requests as the article directs, those challenges fail and the process does not run to completion. After issuing the command “sudo ufw allow ‘Nginx Full’”, the certbot setup and the certbot.timer both behave as expected.

This means that my firewall configuration is a little more porous than the one recommended in the tutorial.

CAA record is needed in digital ocean for this to work completely It wasnt in your tutorial I suggest you guys add it.

Though it is in another article https://docs.digitalocean.com/products/networking/dns/how-to/create-caa-records/

this is great, work like a charm. thank you.

Hello, Thanks for the perfect article. I have an issue that I didn’t fix and maybe you have an idea.

I have three applications on the server, two of them are front-end applications coded by Vue. Both are OK.

**The third application is a backend app with ExpressJS. My requests to ExpressJS Backend App are so slow. The especially first request took almost a minute on browsers. Browsers wait until get a response. When I try with a postman throw a time-out error. **

I was very fast before SSL.

I saw the below error, console sometimes. ** “connect ETIMEDOUT” **

Web: https://www.anurbanite.com/ Rest: https://api.anurbanite.com/api/v1/product

a few major observations. Installing via apt-get will as of 2021-11-01 install version 0.40. snap installs a much more recent version (1.20.0) and can help avoid some bugs.

Additionally, the perl module needs to be removed or disabled from the nginx installation if you wish to avoid rebooting after installing/renewing a cert via certbot. From that point on, changes to nginx .conf files will pass nginx -t but sudo service nginx restart will fail.

etc/nginx/modules-enabled/50-mod-http-perl.conf remove or neuter # load_module modules/ngx_http_perl_module.so;

I have wish to access my website’s IP using https with self-signed cert as Let’s Encrypt does not provide certificates for public IP addresses. I followed this guide and wrote an nginx server block. I can access https://example-ip-address with:

server {
    listen 443 ssl;
    listen [::]:443 ssl;
    include /etc/nginx/snippets/self-signed.conf;
    include /etc/nginx/snippets/ssl-params.conf;

    server_name 123.123.12.123;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/user/djangotemplates;
    }

    location / {
        include /etc/nginx/proxy_params;
        proxy_pass http://unix:/run/gunicorn.sock;
    }

}


server {
    listen 80;
    listen [::]:80;

    server_name 123.123.12.123;

    return 301 https://$server_name$request_uri;
}

And, I can access https://example.com and https://www.example.com with let’s encrypt SSL cert by following this tutorial’s guide and this is the server block I wrote:

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

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/user/djangotemplates;
    }

    location / {
        include proxy_params;
        proxy_pass http://unix:/run/gunicorn.sock;
    }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot



}

server {
    if ($host = www.example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    listen 80;
    server_name www.example.com example.com;
    return 404; # managed by Certbot




}

The problem here is when I put both server blocks into one single configuration file and access https://example-ip-address, the connection is then not encrypted. However, it works fine for https://example.com and https://www.example.com. Any idea what went wrong here?

I just started my django website live on digital ocean - and I received an error email ‘Invalid HTTP_HOST header: ‘123.123.12.123’. You may need to add ‘123.123.12.123’ to ALLOWED_HOSTS.’ So, I added the ip address in the ALLOWED_HOSTS. And I think it’s safer to visit the ip address with https.

A little helper to future students: I kept getting an error that I was seeing a timeout when attempting to renew my certification. It timed out while looking for the A domain name. Enabling IPV6 fixed it. I didn’t realize that certbot would want to renew over IPV6, and it wasn’t enabled by default, so it was causing issues with an inability to look my site up. This poor guide has to cover a lot, but I would recommend including that as an update for frustrated persons trying to figure out why certbot won’t renew.

@bboucheron, what about if we have a DigitalOcean Cloud Firewall instead of using the internal ufw one? How do we set the Cloud one up to allow Let’s Encrypt connections?

I followed How To Secure Apache with Let’s Encrypt on Ubuntu 20.04. I came correctly upto step 4. but i got waiting for verification… challenge failed for domain www.saia4tvet.com http-01 challenge for www.saia4tvet.com cleaning up challenges some challenges have failed.