SSL certificate installation with DigiCert®

ADMAT Bandara
5 min readSep 9, 2019

Here is my story about SSL certificates. I got this ongoing project at my workplace and the site is already secured with SSL. And at the end of its expiration the site went down. (You know how it feels as the developer). I write this article to acknowledge my procedures.

Let’s have some basic knowledge first:

HTTPS — Hypertext Transfer Protocol Secure

Basically it communicates securely through the computer network. This HTTP can be secured by TLS or SSL. Mainly once you secure the transfer it protects against “man-in-the-middle attacks”. As an example, the protection from eavesdropping and tempering. This all happen because of the bidirectional encryption of communication between the client and the server.

SSL — Secure Sockets Layer

TLS — Transport Layer Security

To make the site secure

To create a secure connection to the site we need the SSL certificate. This certificate can be generated and obtained by a Certification Authority (CA). There are many Certification authorities available. Most popular agents are

W3Techs survey from May 2018

My story amends with the CA — DigiCert ®

SSL Certificate

This contains a key pair.

  1. Public Key
  2. Private Key

Above keys are used to establish a encrypted connection. Also SSL Certificate will contain your

  1. Domain name
  2. Company name
  3. Address
  4. City
  5. State
  6. Country
  7. Expiration date of the Certificate and details of the CA

Here are the steps to generate and install the SSL certificate.

My project is with Ruby on Rails + Nginx, And my server runs Ubuntu.

Step 01 — Create a CSR

CSR — Certificate Signing Request

We must create a CSR before ordering a SSL certificate.

CSR in an encoded file with the public key and some information that requires to identify the company.

To generate the CSR, following would help. (change the test to your domain name)

openssl req -new -newkey rsa:2048 -nodes -keyout test-domain.key -out test-domain.csr

Once this runs, it asked many question about the organization.

Once completed you list the CSR and the KEY

This is how it looks like inside the CSR

So, in my server, I created a folder named as “ssl”. I did this process inside that folder. So now I have both CSR and the server private key.

Step 02 — Create the SSL certificate

We have bought the certificate from GeoTrust

The certificate will be sent through an email and it will look


[encoded data]


According to the certificate chain we also need the Intermediate CA certificate. This certificate will also look like above. We can fin the intermediate CA certificates from this link.

Finally, we have to concatenate both Intermediate CA certificate and the SSL certificate. We can simple do that process and see the certificate from a single command.

cat ssl_certificate.crt IntermeidateCA.crt >> domain_name.crt

That’s all. Now you have the full certificate with you. Let’s move to the next step.

Step 03 —Install the certificate into the Nginx

Here is the Nginx Config file of mine.

upstream puma {
server unix:///shared/tmp/sockets/pml_prod-puma.sock;
# Force https for http requests
server {
listen 80;
listen [::]:80;
return 301 https://$host$request_uri;
server {
charset utf-8;
listen 443;ssl on;
ssl_certificate /home/deploy/ssl/test-cert.crt;
ssl_certificate_key /home/deploy/ssl/private-key.key;
# side note: only use TLS since SSLv2 and SSLv3 have had recent vulnerabilities
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
#listen 80 default_server deferred;
root /home/deploy/pml_prod/current/public;
access_log /log/nginx.access.log;
error_log /log/nginx.error.log info;
location ^~ /assets/ {
gzip_static on;
expires max;
add_header Cache-Control public;
# Allow CORS
add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Mx-ReqToken,X-Requested-With';
try_files $uri/index.html $uri @puma;
location @puma {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://puma;
error_page 500 502 503 504 /500.html;
client_max_body_size 10M;
keepalive_timeout 10;

Only part necessary for the SSL is

listen 443;ssl on;ssl_certificate /home/deploy/ssl/test-cert.crt;
ssl_certificate_key /home/deploy/ssl/private-key.key;

Step 04 — Restart the Server Nginx

we have to restart the Nginx

sudo /etc/init.d/nginx restart

Step 05 — Verify the Security

Also, It is better to verify the security. There is a ssltool provided by DigiCert for verification. Here is the link for that.

or else open the following site with the domain-name as a host in params.

Here is the result of our server domain.

The End…