Setting up a SSL Cert from Comodo

I use <>_ as a registrar, and they resale SSL Certs from a number of other companies, including Comodo <>_.

These are the steps I went through to set up an SSL cert.

Purchase the cert

Prior to purchasing a cert, you need to generate a private key, and a CSR file (Certificate Signing Request). You'll be asked for the content of the CSR file when ordering the certificate.


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

This gives you two files:

  • example_com.key -- your Private key. You'll need this later to configure ngxinx.
  • example_com.csr -- Your CSR file.

Now, purchase the certificate [1]_, follow the steps on their site, and you should soon get an email with your PositiveSSL Certificate. It contains a zip file with the following:

  • Root CA Certificate - AddTrustExternalCARoot.crt
  • Intermediate CA Certificate - COMODORSAAddTrustCA.crt
  • Intermediate CA Certificate - COMODORSADomainValidationSecureServerCA.crt
  • Your PositiveSSL Certificate - www_example_com.crt (or the subdomain you gave them)

Install the Commodo SSL cert

Combine everything for nginx [2]_:

  1. Combine the above crt files into a bundle (the order matters, here)::

    cat wwwexamplecom.crt COMODORSADomainValidationSecureServerCA.crt COMODORSAAddTrustCA.crt AddTrustExternalCARoot.crt > ssl-bundle.crt

  2. Store the bundle wherever nginx expects to find it::

    mkdir -p /etc/nginx/ssl/examplecom/ mv ssl-bundle.crt /etc/nginx/ssl/examplecom/

  3. Ensure your private key is somewhere nginx can read it, as well.::

    mv examplecom.key /etc/nginx/ssl/examplecom/

  4. Make sure your nginx config points to the right cert file and to the private key you generated earlier::

    server { listen 443;

    ssl on;
    ssl_certificate /etc/nginx/ssl/example_com/ssl-bundle.crt;
    ssl_certificate_key /etc/nginx/ssl/example_com/example_com.key;
    # side note: only use TLS since SSLv2 and SSLv3 have had recent vulnerabilities
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    # ...


  5. Restart nginx.

.. [1] I purchased mine through .. [2] Based on these instructions:

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