Knowledge Base

SSL (Secure Sockets Layer) certificates secure the communication between your website and its visitors by encrypting it. This is especially critical when sensitive information (credit card information, personal data, etc.) is being transmitted. Nginx is a high-performance web server, and securing your website using SSL certificates is quite easy. In this comprehensive guide, we will examine the process of installing an SSL certificate on Nginx step by step.

1. What is an SSL Certificate and Why is it Necessary?

SSL (Secure Sockets Layer) is a protocol that encrypts communication over the internet, ensuring that data is transmitted securely. An SSL certificate is a digital certificate that verifies the identity of a website and encrypts the connection between visitors and the server. Today, using an SSL certificate for your website has become almost mandatory. Here are some important reasons why an SSL certificate is necessary:

• Data Encryption: An SSL certificate encrypts the communication between your website and its visitors, ensuring that sensitive data (username, password, credit card information, etc.) is transmitted securely.
• Identity Verification: An SSL certificate verifies the identity of your website, ensuring that your visitors are connecting to the correct website.
• SEO (Search Engine Optimization): Search engines like Google prioritize websites that use SSL certificates. Therefore, using an SSL certificate can improve your website's search engine ranking.
• Reliability: An SSL certificate increases the reliability of your website and ensures that your visitors trust your website.
• Compliance: In some industries (e-commerce, finance, etc.), using an SSL certificate is a legal requirement.

1.1 Types of SSL Certificates

There are various types of SSL certificates for different needs. Here are the most common types of SSL certificates:

• Domain Validated (DV) SSL: The most basic type of SSL certificate. It only verifies the ownership of the domain name. It is fast and cost-effective.
• Organization Validated (OV) SSL: Includes a more comprehensive verification process than DV SSL. In addition to the domain name, it also verifies the organization's information. Provides more trust.
• Extended Validation (EV) SSL: The type of SSL certificate that offers the highest level of security. It verifies the organization's identity in the most detailed way and displays a green address bar in the browser.
• Wildcard SSL: Protects all subdomains of a domain name (e.g., *.example.com) with a single certificate.
• Multi-Domain SSL (SAN SSL): Protects multiple domain names with a single certificate.

1.2 How to Obtain an SSL Certificate?

You can obtain an SSL certificate in various ways:

• Paid SSL Certificates: You can purchase a paid SSL certificate from trusted certificate providers such as Comodo, DigiCert, and Sectigo.
• Free SSL Certificates: You can obtain a free SSL certificate from certificate providers such as Let's Encrypt. Let's Encrypt is an automated and open-source certificate authority.

2. Nginx Installation and Basic Configuration

Before installing an SSL certificate on Nginx, Nginx must be installed and configured correctly on your server. In this section, we will examine the Nginx installation and basic configuration step by step.

2.1 Nginx Installation (Example: Ubuntu)

If you are using an Ubuntu or Debian-based system, you can install Nginx using the following commands:

sudo apt update
sudo apt install nginx

After the installation is complete, you can use the following command to check if Nginx is running:

sudo systemctl status nginx

If Nginx is not running, you can start it with the following command:

sudo systemctl start nginx

2.2 Basic Nginx Configuration

Nginx's main configuration file is usually located at `/etc/nginx/nginx.conf`. Your website's configuration file is usually located in the `/etc/nginx/sites-available/` directory and is enabled with a symbolic link to the `/etc/nginx/sites-enabled/` directory.

To create a configuration file for a new website, you can follow these steps:

1. Create a new configuration file in the `/etc/nginx/sites-available/` directory (for example, `example.com`):

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

2. Add the following basic configuration to the file:

   
   server {
       listen 80;
       server_name example.com www.example.com;
   
       root /var/www/example.com;
       index index.html index.htm;
   
       location / {
           try_files $uri $uri/ =404;
       }
   }
       

3. Enable the configuration by creating a symbolic link to the `/etc/nginx/sites-enabled/` directory:

   
   sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/
       

4. Check the Nginx configuration:

   
   sudo nginx -t
       

5. Restart Nginx:

   
   sudo systemctl restart nginx
       

3. Creating or Obtaining an SSL Certificate

To install an SSL certificate on Nginx, you must first obtain an SSL certificate. In this section, we will examine both free (Let's Encrypt) and paid SSL certificate acquisition methods.

3.1 Creating a Free SSL Certificate with Let's Encrypt

Let's Encrypt is a free, automated, and open certificate authority. You can use a tool called Certbot to create an SSL certificate with Let's Encrypt.

1. Install Certbot:

   
   sudo apt install certbot python3-certbot-nginx
       

2. Run Certbot and specify your domain name:

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

3. Certbot will automatically update your Nginx configuration and install the SSL certificate.

Certbot will create a cron job to automatically renew the SSL certificate. Certificates are usually valid for 90 days, and Certbot renews them automatically.

3.2 Obtaining a Paid SSL Certificate and Preparing the Files

If you have purchased a paid SSL certificate, your certificate provider will provide you with the following files:

• Certificate File (example.com.crt or example.com.pem): Contains your website's certificate.
• Intermediate Certificate File (ca-bundle.crt or ca.pem): Required to complete the certificate chain.
• Private Key File (example.com.key): Contains the private key used to create the certificate.

Copy these files to a secure location on your server (e.g., the `/etc/ssl/certs/` and `/etc/ssl/private/` directories).

4. Installing the SSL Certificate on Nginx

After obtaining the SSL certificate, you can enable SSL by updating your Nginx configuration. In this section, we will examine how to update the Nginx configuration step by step.

4.1 Updating the Nginx Configuration File

Open the `/etc/nginx/sites-available/example.com` file and update it as follows:

server {
    listen 80;
    server_name example.com www.example.com;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    server_name example.com www.example.com;

    root /var/www/example.com;
    index index.html index.htm;

    ssl_certificate /etc/ssl/certs/example.com.crt;
    ssl_certificate_key /etc/ssl/private/example.com.key;
    ssl_trusted_certificate /etc/ssl/certs/ca-bundle.crt; # If required

    location / {
        try_files $uri $uri/ =404;
    }
}

Explanations:

• listen 80: Listens for HTTP (port 80) requests and redirects them to HTTPS (port 443).
• listen 443 ssl: Listens for HTTPS (port 443) requests and enables SSL.
• ssl_certificate: Specifies the path to the certificate file.
• ssl_certificate_key: Specifies the path to the private key file.
• ssl_trusted_certificate: Specifies the path to the intermediate certificate file. (If required)

Important: Make sure you have specified the paths to the certificate and key files correctly.

4.2 Restarting Nginx

After updating the configuration file, restart Nginx to apply the changes:

sudo nginx -t
sudo systemctl restart nginx

It is important to check the configuration with the `nginx -t` command before restarting Nginx. If there are any errors, Nginx cannot be restarted.

5. Optimizing SSL Configuration

After installing the SSL certificate, you can improve security and performance by optimizing your Nginx configuration. In this section, we will examine some important optimization techniques.

5.1 Using Strong Encryption Algorithms

Nginx supports various encryption algorithms. It is important to use strong and up-to-date encryption algorithms to improve security. You can specify the encryption algorithms to be used using the `ssl_ciphers` directive:

ssl_ciphers EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH;

5.2 Configuring the TLS Protocol

TLS (Transport Layer Security) is the successor to SSL and is a more secure protocol. You can use the `ssl_protocols` directive to enable the TLS protocol in Nginx and determine which TLS versions are supported:

ssl_protocols TLSv1.2 TLSv1.3;

5.3 Enabling HSTS (HTTP Strict Transport Security)

HSTS is a security mechanism that forces browsers to always connect to your website over HTTPS. To enable HSTS, you can use the following `add_header` directive:

add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload";

Explanations:

• max-age: Specifies how long HSTS will be valid (in seconds).
• includeSubDomains: Specifies that HSTS will also apply to subdomains.
• preload: Allows your website to be added to the HSTS preload list. This ensures that browsers use HTTPS even when they connect to your website for the first time.

5.4 Enabling OCSP Stapling

OCSP (Online Certificate Status Protocol) Stapling does not require browsers to perform certificate validity checks by regularly checking the certificate validity of the server. This improves performance and protects privacy. To enable OCSP Stapling, you can use the following directives:

ssl_stapling on;
ssl_stapling_verify on;
ssl_trusted_certificate /etc/ssl/certs/ca-bundle.crt;
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;

5.5 Configuring SSL Session Cache

The SSL session cache prevents the server from repeatedly performing SSL handshakes by caching SSL sessions. This improves performance. To configure the SSL session cache, you can use the following directives:

ssl_session_cache shared:SSL:10m;
ssl_session_timeout 10m;

6. SSL Certificate Renewal

SSL certificates are valid for a specific period (usually 90 days or 1 year). You need to renew your certificate before it expires. In this section, we will examine how to renew an SSL certificate.

6.1 Renewing a Let's Encrypt Certificate

Let's Encrypt certificates are generally valid for 90 days. Certbot will create a cron job to automatically renew certificates. However, if you want to renew the certificate manually, you can use the following command:

sudo certbot renew

This command will renew all Let's Encrypt certificates that are about to expire.

6.2 Renewing a Paid SSL Certificate

If you have purchased a paid SSL certificate, your certificate provider will send you a renewal notification before your certificate expires. Follow your certificate provider's instructions to renew your certificate.

After renewing the certificate, upload the new certificate and key files to your server and update your Nginx configuration.

7. Debugging and Troubleshooting

You may encounter various problems during or after the SSL certificate installation process. In this section, we will examine common problems and their solutions.

7.1 "SSL: error:0906D06C:PEM routines:PEM_read_bio:no start line" Error

This error means that Nginx cannot read the certificate or key file. This is usually caused by incorrect file paths or corrupted files. Check the file paths and make sure the files are correct.

7.2 "SSL: error:140A900F:SSL routines:SSL_CTX_load_verify_locations:system lib" Error

This error means that Nginx cannot read the intermediate certificate file (ca-bundle.crt). Check the file path and make sure the file is correct. Make sure you are using the correct version of the intermediate certificate file.

7.3 "Not Secure" Warning in Browser

If your browser shows a "Not Secure" warning on your website, it may be due to the following reasons:

• Certificate Invalid: Your certificate may be expired or invalid. Make sure your certificate is valid.
• Mixed Content: There may be some resources (images, style files, etc.) on your website that are not loaded over HTTPS. Make sure all resources are loaded over HTTPS.
• Incorrect Configuration: There may be an error in your Nginx configuration. Check your configuration and make sure it is correct.

7.4 SSL Test Tools

You can use various online tools to test your SSL configuration and identify potential problems. Here are some popular SSL test tools:

• SSL Labs SSL Server Test: https://www.ssllabs.com/ssltest/
• Qualys SSL Labs: https://www.ssllabs.com/

8. Real-Life Examples and Case Studies

Example 1: E-commerce Site Security

An e-commerce site must use an SSL certificate to protect customer credit card information and personal data. By using an EV SSL certificate, it can increase customer trust by displaying a green address bar in the browser and reduce the risk of fraud.

Example 2: Blog Site SEO Optimization

A blog site can use an SSL certificate to improve search engine ranking and increase visitor trust. By using a free SSL certificate with Let's Encrypt, it can easily ensure site security and improve SEO performance.

Case Study: Preventing Customer Data Breach

A company's website was breached because it was running without an SSL certificate. Attackers stole usernames, passwords, and credit card information. After this incident, the company installed an SSL certificate, increased security measures, and made efforts to regain customer trust.

9. Frequently Asked Questions

• Q1: Why should I use an SSL certificate?
• A1: An SSL certificate encrypts the communication between your website and your visitors, ensuring that data is transmitted securely, verifies the identity of your website, improves SEO performance, and increases visitor trust.
• Q2: Which type of SSL certificate should I choose?
• A2: The type of SSL certificate depends on your website's needs and budget. DV SSL is suitable for basic security. OV SSL provides more trust. EV SSL offers the highest level of security. Wildcard SSL protects subdomains. Multi-Domain SSL protects multiple domain names.
• Q3: Is Let's Encrypt secure?
• A3: Yes, Let's Encrypt is secure. It is a trusted certificate authority and is used by many websites.
• Q4: My SSL certificate has expired, what should I do?
• A4: If your SSL certificate has expired, you should renew it immediately. Otherwise, a "Not Secure" warning may appear on your website and you may lose the trust of your visitors.
• Q5: Is it safe to enable HSTS?
• A5: Yes, enabling HSTS is safe and increases the security of your website. However, before enabling HSTS, make sure your website is running entirely over HTTPS. Otherwise, your website may become inaccessible.

10. Conclusion and Summary

In this comprehensive guide, we have examined the process of installing an SSL certificate on Nginx step by step. We learned what an SSL certificate is, why it is necessary, different types of SSL certificates, how to obtain an SSL certificate, how to install an SSL certificate on Nginx, how to optimize SSL configuration, how to renew an SSL certificate, and how to troubleshoot common problems.

Using an SSL certificate is critical to ensuring the security of your website and increasing the trust of your visitors. By following this guide, you can easily enable SSL on your Nginx web server and maximize the security of your website.