Configure Digital Ocean for ssl (https) for free, (Bonus Meteor setup) — Video Series — Part 4

Now that we have the user and the domain names setup for our deployment, let’s move on to installing the Let’s Encrypt client software.

This is Part 4 in the entire video series — you can find the previous parts here.. Part 1, Part 2 and Part 3.

Here is the video for the below steps. Happy Learning and Doing!

Step 1: Install Let’s Encrypt Client

The first step to using Let’s Encrypt to obtain an SSL certificate is to install the letsencrypt software on your server. Currently, the best way to install Let’s Encrypt is to simply clone it from the official GitHub repository. In the future, it will likely be available via a package manager.

Install Git and bc

Let’s install Git and bc now, so we can clone the Let’s Encrypt repository.

Update your server’s package manager with this command:

sudo apt-get update

Install Let’s Encrypt

We can now the Let’s Encrypt with this command:

sudo apt-get install letsencrypt

This is how the output should look like.

let’s encrypt setup

Step 2: Obtain an SSL Certificate

We’ll show you how to use the Webroot plugin to obtain an SSL certificate.

If you haven’t installed Nginx yet, do so by following this tutorial. Continue below when you are finished.

How To Use the Webroot Plugin

The Webroot plugin works by placing a special file in the /.well-known directory within your document root, which can be opened (through your web server) by the Let’s Encrypt service for validation. Depending on your configuration, you may need to explicitly allow access to the /.well-known directory.

To ensure that the directory is accessible to Let’s Encrypt for validation, let’s make a quick change to our Nginx configuration. By default, it’s located at /etc/nginx/sites-available/default. We’ll use nano to edit it:

sudo nano /etc/nginx/sites-available/default

Inside the server block, add this location block:

location ~ /.well-known {
        allow all;
}

Note, that there should also be an existing default location, you can place this new location, just below the existing location.

add location

You will also want look up what your document root is set to by searching for the root directive, as the path is required to use the Webroot plugin. If you’re using the default configuration file, the root will be /var/www/html.

Save and exit.

Check your configuration for syntax errors:

sudo nginx -t

Reload Nginx with this command:

sudo systemctl reload nginx

Now that we know our webroot-path, we can use the Webroot plugin to request an SSL certificate with these commands. Here, we are also specifying our domain names with the -d option. If you want a single cert to work with multiple domain names (e.g. example.com and www.example.com), be sure to include all of them. Also, make sure that you replace the bold parts with the appropriate webroot path and domain name(s):

sudo letsencrypt certonly -a webroot --webroot-path=/var/www/html -d example.com -d www.example.com

For coolmoviebites app, we are going to use:

sudo letsencrypt certonly -a webroot --webroot-path=/var/www/html -d coolmoviebites.com

Note: The Let’s Encrypt software requires superuser privileges, so you will be required to enter your password if you haven’t used sudo recently.

After letsencrypt initializes, you will be prompted for some information. The exact prompts may vary depending on if you’ve used Let’s Encrypt before, but we’ll step you through the first time.

At the prompt, enter an email address that will be used for notices and lost key recovery:

email prompt

Then you must agree to the Let’s Encrypt Subscribe Agreement. Select Agree:

agree to the terms

If everything was successful, you should see an output message that looks something like this:

Output:
IMPORTANT NOTES:
 - If you lose your account credentials, you can recover through
   e-mails sent to sammy@digitalocean.com
 - Congratulations! Your certificate and chain have been saved at
   /etc/letsencrypt/live/example.com/fullchain.pem. Your
   cert will expire on 2016-03-15. To obtain a new version of the
   certificate in the future, simply run Let's Encrypt again.
 - Your account credentials have been saved in your Let's Encrypt
   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 Let's
   Encrypt so making regular backups of this folder is ideal.
 - If like Let's Encrypt, 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 will want to note the path and expiration date of your certificate, which was highlighted in the example output.

Certificate Files

After obtaining the cert, you will have the following PEM-encoded files:

• cert.pem: Your domain’s certificate
• chain.pem: The Let’s Encrypt chain certificate
• fullchain.pem: cert.pem and chain.pem combined
• privkey.pem: Your certificate’s private key

It’s important that you are aware of the location of the certificate files that were just created, so you can use them in your web server configuration. The files themselves are placed in a subdirectory in /etc/letsencrypt/archive. However, Let’s Encrypt creates symbolic links to the most recent certificate files in the /etc/letsencrypt/live/your_domain_name directory. Because the links will always point to the most recent certificate files, this is the path that you should use to refer to your certificate files.

You can check that the files exist by running this command (substituting in your domain name):

sudo ls -l /etc/letsencrypt/live/your_domain_name

The output should be the four previously mentioned certificate files. In a moment, you will configure your web server to use fullchain.pem as the certificate file, and privkey.pem as the certificate key file.

Generate Strong Diffie-Hellman Group

To further increase security, you should also generate a strong Diffie-Hellman group. To generate a 2048-bit group, use this command:

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

This may take a few minutes but when it’s done you will have a strong DH group at /etc/ssl/certs/dhparam.pem.

Step 3: Configure TLS/SSL on Web Server (Nginx)

Now that you have an SSL certificate, you need to configure your Nginx web server to use it.

We will make a few adjustments to our configuration:

1. We will create a configuration snippet containing our SSL key and certificate file locations.
2. We will create a configuration snippet containing strong SSL settings that can be used with any certificates in the future.
3. We will adjust the Nginx server blocks to handle SSL requests and use the two snippets above.

This method of configuring Nginx will allow us to keep clean server blocks and put common configuration segments into reusable modules.

Create a Configuration Snippet Pointing to the SSL Key and Certificate

First, let’s create a new Nginx configuration snippet in the /etc/nginx/snippets directory.

To properly distinguish the purpose of this file, we will name it ssl- followed by our domain name, followed by .conf on the end:

sudo nano /etc/nginx/snippets/ssl-example.com.conf

In our case, it will be:

sudo nano /etc/nginx/snippets/ssl-coolmoviebites.com.conf

Within this file, we just need to set the ssl_certificate directive to our certificate file and the ssl_certificate_key to the associated key. In our case, this will look like this:

/etc/nginx/snippets/ssl-coolmoviebites.com.conf

ssl_certificate /etc/letsencrypt/live/coolmoviebites.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/coolmoviebites.com/privkey.pem;

When you’ve added those lines, save and close the file. Make sure to replace your apps domain name instead of ‘game.coolmoviebites’

Create a Configuration Snippet with Strong Encryption Settings

Next, we will create another snippet that will define some SSL settings. This will set Nginx up with a strong SSL cipher suite and enable some advanced features that will help keep our server secure.

The parameters we will set can be reused in future Nginx configurations, so we will give the file a generic name:

sudo nano /etc/nginx/snippets/ssl-params.conf

To set up Nginx SSL securely, we will be using the recommendations by Remy van Elst on the Cipherli.stsite. This site is designed to provide easy-to-consume encryption settings for popular software. You can read more about his decisions regarding the Nginx choices here.

Note: The default suggested settings on Cipherli.st offer strong security. Sometimes, this comes at the cost of greater client compatibility. If you need to support older clients, there is an alternative list that can be accessed by clicking the link on the link labeled “Yes, give me a ciphersuite that works with legacy / old software.”

The compatibility list can be used instead of the default suggestions in the configuration below. The choice of which config you use will depend largely on what you need to support.

For our purposes, we can copy the provided settings in their entirety. We just need to make a few small modifications.

First, we will add our preferred DNS resolver for upstream requests. We will use Google’s for this guide. We will also go ahead and set the ssl_dhparam setting to point to the Diffie-Hellman file we generated earlier.

Finally, you should take take a moment to read up on HTTP Strict Transport Security, or HSTS, and specifically about the “preload” functionality. Preloading HSTS provides increased security, but can have far reaching consequences if accidentally enabled or enabled incorrectly. In this guide, we will not preload the settings, but you can modify that if you are sure you understand the implications:

/etc/nginx/snippets/ssl-params.conf

# from https://cipherli.st/
# and https://raymii.org/s/tutorials/Strong_SSL_Security_On_nginx.html
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH";
ssl_ecdh_curve secp384r1;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;
ssl_stapling on;
ssl_stapling_verify on;
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
# Disable preloading HSTS for now.  You can use the commented out header line that includes
# the "preload" directive if you understand the implications.
#add_header Strict-Transport-Security "max-age=63072000; includeSubdomains; preload";
add_header Strict-Transport-Security "max-age=63072000; includeSubdomains";
add_header X-Frame-Options DENY;
add_header X-Content-Type-Options nosniff;
ssl_dhparam /etc/ssl/certs/dhparam.pem;

Save and close the file when you are finished.

Adjust the Nginx Configuration to Use SSL

Now that we have our snippets, we can adjust our Nginx configuration to enable SSL.

We will assume in this guide that you are using the default server block file in the /etc/nginx/sites-available directory. If you are using a different server block file, substitute it’s name in the below commands.

Before we go any further, let’s back up our current server block file:

sudo cp /etc/nginx/sites-available/default /etc/nginx/sites-available/default.bak

Now, open the server block file to make adjustments:

sudo nano /etc/nginx/sites-available/default

Inside, your server block probably begins like this:

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    # SSL configuration
    # listen 443 ssl default_server;
    # listen [::]:443 ssl default_server;
    . . .

We will be modifying this configuration so that unencrypted HTTP requests are automatically redirected to encrypted HTTPS. This offers the best security for our sites. If you want to allow both HTTP and HTTPS traffic, use the alternative configuration that follows.

We will be splitting the configuration into two separate blocks. After the two first listen directives, we will add a server_name directive, set to your server’s domain name. We will then set up a redirect to the second server block we will be creating. Afterwards, we will close this short block:

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_name game.coolmovites.com 
    # example.com www.example.com;
    return 301 https://$server_name$request_uri;
}
    # SSL configuration
    # listen 443 ssl default_server;
    # listen [::]:443 ssl default_server;
    . . .

Next, we need to start a new server block directly below to contain the remaining configuration. We can uncomment the two listen directives that use port 443. We can add http2 to these lines in order to enable HTTP/2 within this block. Afterwards, we just need to include the two snippet files we set up:

Note: You may only have one listen directive that includes the default_server modifier for each IP version and port combination. If you have other server blocks enabled for these ports that have default_server set, you must remove the modifier from one of the blocks.

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_name example.com www.example.com;
    return 301 https://$server_name$request_uri;
}
server {
    # SSL configuration
    listen 443 ssl http2 default_server;
    listen [::]:443 ssl http2 default_server;
    include snippets/ssl-example.com.conf;
    include snippets/ssl-params.conf;
    . . .

Save and close the file when you are finished.

(Alternative Configuration) Allow Both HTTP and HTTPS Traffic

If you want or need to allow both encrypted and unencrypted content, you will have to configure Nginx a bit differently. This is generally not recommended if it can be avoided, but in some situations it may be necessary. Basically, we just compress the two separate server blocks into one block and remove the redirect:

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    listen 443 ssl http2 default_server;
    listen [::]:443 ssl http2 default_server;
    server_name game.coolmoviebites.com
    # example.com www.example.com;
    include snippets/ssl-example.com.conf;
    include snippets/ssl-params.conf;
    . . .

Save and close the file when you are finished.

Step 4: Adjust 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 SSL traffic. Luckily, Nginx registers a few profiles with ufw upon installation.

You can see the current setting by typing:

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, we can allow the “Nginx Full” profile and then delete the redundant “Nginx HTTP” profile allowance:

sudo ufw allow ‘Nginx Full’
sudo ufw delete allow ‘Nginx HTTP’

Your status should look like this now:

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)

Step 5: Enabling the Changes in Nginx

Now that we’ve made our changes and adjusted our firewall, we can restart Nginx to implement our new changes.

First, we should check to make sure that there are no syntax errors in our files. We can do this by typing:

sudo nginx -t

If everything is successful, you will get a result that looks like this:

Output
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

If your output matches the above, your configuration file has no syntax errors. We can safely restart Nginx to implement our changes:

sudo systemctl restart nginx

The Let’s Encrypt TLS/SSL certificate is now in place and the firewall now allows traffic to port 80 and 443. At this point, you should test that the TLS/SSL certificate works by visiting your domain via HTTPS in a web browser.

You can use the Qualys SSL Labs Report to see how your server configuration scores:

In a web browser:
https://www.ssllabs.com/ssltest/analyze.html?d=example.com

This SSL setup should report an A+ rating.

Step 6: Set Up Auto Renewal

Let’s Encrypt certificates are valid for 90 days, but it’s recommended that you renew the certificates every 60 days to allow a margin of error. At the time of this writing, automatic renewal is still not available as a feature of the client itself, but you can manually renew your certificates by running the Let’s Encrypt client with the renew option.

To trigger the renewal process for all installed domains, run this command:

sudo letsencrypt renew

Because we recently installed the certificate, the command will only check for the expiration date and print a message informing that the certificate is not due to renewal yet. The output should look similar to this:

Output:
Checking for new version...
Requesting root privileges to run letsencrypt...
   /root/.local/share/letsencrypt/bin/letsencrypt renew
Processing /etc/letsencrypt/renewal/example.com.conf
The following certs are not due for renewal yet:
  /etc/letsencrypt/live/example.com/fullchain.pem (skipped)
No renewals were attempted.

Notice that if you created a bundled certificate with multiple domains, only the base domain name will be shown in the output, but the renewal should be valid for all domains included in this certificate.

A practical way to ensure your certificates won’t get outdated is to create a cron job that will periodically execute the automatic renewal command for you. Since the renewal first checks for the expiration date and only executes the renewal if the certificate is less than 30 days away from expiration, it is safe to create a cron job that runs every week or even every day, for instance.

Let’s edit the crontab to create a new job that will run the renewal command every week. To edit the crontab for the root user, run:

sudo crontab -e

Add the following lines:

30 2 * * 1 /usr/bin/letsencrypt renew >> /var/log/le-renew.log
35 2 * * 1 /bin/systemctl reload nginx

Save and exit.

This will create a new cron job that will execute the letsencrypt-auto renew command every Monday at 2:30 am, and reload Nginx at 2:35am (so the renewed certificate will be used). The output produced by the command will be piped to a log file located at /var/log/le-renewal.log.

For more information on how to create and schedule cron jobs, you can check our How to Use Cron to Automate Tasks in a VPS guide.

Conclusion

So, we have successfully got the https setup done on our Digital Ocean droplet — Free of cost. I hope this series helps someone.

if(want to see meteor deployment){
  goto Part 5
} else {
  console.log('Thank you');
  console.log('Spread the word about coolmoviebites.com');
  console.log('Even better, be a part of the community!');
}