Setting up a SSL Cert from 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]:

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

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

Store the bundle wherever nginx expects to find it:

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

Ensure your private key is somewhere nginx can read it, as well.:
```
mv example_com.key /etc/nginx/ssl/example_com/
```

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;

    # ...

}

Restart nginx.