OpenSSL Generate CSR & SSL Certificate Installation: A Comprehensive Guide

Securing your website or application starts with obtaining an SSL/TLS certificate. Two fundamental steps in this process are generating a Certificate Signing Request (CSR) to apply for the certificate and then installing the issued certificate onto your server. For administrators who prefer the command line or work in environments where graphical tools aren’t available (like many Linux distributions), using the powerful OpenSSL toolkit is the standard way to OpenSSL Generate CSR. Once the Certificate Authority (CA) issues your certificate based on that CSR, the next critical phase is the ssl certificate installation on your web server.

This guide provides a detailed walkthrough of generating a CSR using OpenSSL commands and then outlines the general principles and common steps involved in installing the SSL certificate on popular web server platforms, ensuring you can effectively secure your services with certificates from trusted providers like sslrepo.com.

Key Takeaways

• OpenSSL: A versatile command-line tool essential for many SSL/TLS tasks, including CSR generation.
• CSR Generation: The process to OpenSSL Generate CSR creates two outputs: the CSR file (sent to the CA) and a corresponding private key file (kept secret on your server).
• Private Key Security: Protecting the generated private key (.key file) is paramount. Never share it.
• CSR Accuracy: Information provided during CSR generation (Common Name, Organization, etc.) must be accurate.
• SSL Installation: The ssl certificate installation process involves configuring your web server (Apache, Nginx, IIS, etc.) to use the issued certificate, its private key, and any necessary intermediate certificates.
• Platform Differences: Installation steps vary significantly depending on your web server software.
• Verification: Always test your installation thoroughly after completion.

Part 1: How to OpenSSL Generate CSR

A CSR contains your server’s public key and identifying information, encoded for the CA. Generating it with OpenSSL also creates your private key.

The Basic Command:

The most common command to generate a CSR and a new private key simultaneously is:

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

Explanation of Command Options:

• openssl req: Invokes the OpenSSL utility for creating certificate requests (CSRs) and certificates.
• -new: Specifies that you want to generate a new CSR.
• -newkey rsa:2048: Generates a new RSA private key with a bit length of 2048 bits (the current industry standard minimum). You can use higher values like 3072 or 4096. This simultaneously creates the public key that goes into the CSR.
• -nodes: (Important) Stands for “No DES”. This option prevents OpenSSL from encrypting your private key with a passphrase. While encrypting the key adds a layer of security, most web servers (Apache, Nginx) require an unencrypted private key to start automatically without manual intervention. If you do want passphrase protection, omit -nodes, but remember you’ll need to enter the passphrase every time your server restarts.
• -keyout yourdomain.key: Specifies the filename where the newly generated private key will be saved. Protect this file!
• -out yourdomain.csr: Specifies the filename where the generated CSR will be saved. This is the file you send to the CA.

Interactive Prompts:

After running the command, OpenSSL will prompt you to enter the “Distinguished Name” information:

1. Country Name (2 letter code): E.g., US, GB, CA.
2. State or Province Name (full name): E.g., California, New York (do not abbreviate).
3. Locality Name (eg, city): E.g., Los Angeles, London.
4. Organization Name (eg, company): Your full legal company name. (Required for OV/EV certs).
5. Organizational Unit Name (eg, section): Your department, like IT Department or Web Security. (Optional for many cert types).
6. Common Name (e.g. server FQDN or YOUR name): CRITICAL! This must be the exact, fully qualified domain name (FQDN) that users will use to access your site via HTTPS (e.g., www.yourdomain.com, secure.example.org). For Wildcard certificates, enter *.yourdomain.com.
7. Email Address: (Generally optional, can often be left blank).
8. Challenge Password / Optional Company Name: (These are legacy fields – leave them blank by pressing Enter). Do NOT set a challenge password.

Generating CSR with SANs (Subject Alternative Names):

If you need your certificate to cover multiple hostnames (e.g., www.yourdomain.com AND yourdomain.com), you need a SAN certificate. Generating a CSR with SANs using OpenSSL usually requires a configuration file (.cnf). You’d modify the command slightly and reference the config file:

openssl req -new -newkey rsa:2048 -nodes -keyout yourdomain.key -out yourdomain.csr -config your_openssl.cnf

The .cnf file would contain sections specifying the SANs under [alt_names] referenced by subjectAltName = @alt_names within an extensions section ([v3_req]). Creating these config files requires careful syntax.

After Generation:

• You will have two files: yourdomain.key (your secret private key) and yourdomain.csr (your request file).
• Secure your .key file immediately. Set strict file permissions (readable only by root or the webserver user). Back it up securely.
• Open the .csr file with a text editor and copy the entire content (including -----BEGIN... and -----END... lines) to submit to your CA/Reseller (like sslrepo.com) during the ordering process.

Part 2: SSL Certificate Installation (General Process)

Once the CA validates your CSR and issues the certificate (usually providing a .crt or .cer file for your domain, plus intermediate/bundle files), you need to install them on your server.

This process varies significantly based on your web server software (Apache, Nginx, IIS, Tomcat, etc.). Below are the general principles:

1. Upload Certificate Files: Transfer the issued certificate file(s) (your server certificate and the CA bundle/intermediate certificates) to your server. Store them in a secure directory accessible by your web server configuration (e.g., /etc/ssl/certs/ on Linux, or a designated folder on Windows).
2. Locate Private Key: Ensure the private key file (.key) you generated earlier is also in a secure location on the server, readable by the web server process.
3. Configure Your Web Server: This is the platform-specific part. You need to edit your web server’s configuration files to tell it where the certificate files and private key are located and to enable SSL/TLS for your website.
   • Apache: Edit your Virtual Host configuration (often in /etc/apache2/sites-available/your-site.conf). You’ll typically need directives like:
     • SSLEngine on
     • SSLCertificateFile /path/to/yourdomain.crt (Your server certificate)
     • SSLCertificateKeyFile /path/to/yourdomain.key (Your private key)
     • SSLCertificateChainFile /path/to/intermediate_bundle.crt (The CA bundle/intermediates) – Note: Directive name might vary slightly based on Apache version.
   • Nginx: Edit your server block configuration (often in /etc/nginx/sites-available/your-site or /etc/nginx/conf.d/your-site.conf). Directives typically include:
     • listen 443 ssl;
     • ssl_certificate /path/to/yourdomain_bundle.crt; (Requires server cert + intermediates concatenated into ONE file)
     • ssl_certificate_key /path/to/yourdomain.key; (Your private key)
     • (Concatenation: cat yourdomain.crt intermediate_bundle.crt > yourdomain_bundle.crt)
   • IIS (Windows):
     • Use “Complete Certificate Request” in Server Certificates if you generated the CSR on that IIS server. Provide the .crt file from the CA.
     • If you have a .pfx file (containing cert+key), use the “Import” function in Server Certificates.
     • Go to your site’s Bindings, add/edit the HTTPS binding (port 443), and select the newly installed certificate from the dropdown.
   • Other Servers (Tomcat, etc.): Consult the specific documentation for your server software. Often involves configuring keystores or specific connector settings.
4. Install Intermediate Certificates: Ensure the CA’s intermediate certificates are correctly referenced or installed. Missing intermediates cause browser trust errors. For Apache/Nginx, this is handled by the chain/bundle file directives. For IIS, intermediates often need to be installed in the “Intermediate Certification Authorities” store (sometimes happens automatically when completing the request or importing a PFX containing the chain).
5. Restart/Reload Web Server: After saving configuration changes, you must restart or reload your web server service for the changes to take effect (e.g., sudo systemctl restart apache2, sudo systemctl reload nginx, iisreset).

Part 3: Verification

Crucial: Always test your installation!

• Use multiple browsers to access your site via https://yourdomain.com. Check for padlock icons and no warnings.
• Use online SSL checker tools (e.g., Qualys SSL Labs) for a comprehensive analysis of your certificate, chain, and server configuration.
• Use openssl s_client -connect yourdomain.com:443 -servername yourdomain.com to check the certificate presented by the server directly.

Conclusion

Generating a CSR with OpenSSL gives you command-line control over creating your certificate request and private key. While the OpenSSL Generate CSR process is standardized, the subsequent ssl certificate installation is highly dependent on your server environment. Always follow the specific documentation for your web server software (Apache, Nginx, IIS, etc.), ensure intermediate certificates are installed, and rigorously test your configuration after installation to confirm secure HTTPS operation.

Ready to get your certificate after generating your CSR? Submit your CSR and purchase trusted SSL certificates from leading CAs at sslrepo.com.

Frequently Asked Questions (FAQ)

Q1: What are the two main files created when I run openssl req -new -newkey?
A: You get a .csr file (Certificate Signing Request, sent to the CA) and a .key file (your private key, kept secret on your server).

Q2: What happens if I lose my private key (.key file)?
A: You cannot install the SSL certificate issued for the corresponding CSR. You will need to generate a new CSR (which creates a new private key) and have the CA re-issue the certificate based on the new CSR. Protect your private key!

Q3: What is the most important field to get right in the CSR?
A: The Common Name (CN). It must exactly match the domain name users will type into their browser to reach your site securely.

Q4: Can I use the same CSR for certificate renewal?
A: It’s strongly recommended to generate a new CSR (and thus a new private key) for every renewal as a security best practice.

Q5: How do I install the intermediate certificates provided by my CA?
A: This depends on your server:
* Apache: Use SSLCertificateChainFile or SSLCACertificateFile directive pointing to the bundle file.
* Nginx: Concatenate your server cert and the intermediate bundle into one file referenced by ssl_certificate.
* IIS: Often imported automatically when completing the request or importing a PFX. If not, manually import the intermediate .crt file into the “Intermediate Certification Authorities” store via MMC or double-clicking.

Q6: My installation seems complete, but I get errors. What should I check?
A: Verify:
* Correct certificate files and private key are referenced in the config.
* File permissions allow the web server to read the key and cert files.
* Intermediate certificates are correctly installed/referenced.
* The web server service was restarted/reloaded after config changes.
* Firewall rules allow traffic on port 443.
* Use an online SSL checker for detailed diagnostics.