- https://wiki.debian.org/Self-Signed_Certificate
- http://www.linux.com/learn/tutorials/392099-creating-self-signed-ssl-certificates-for-apache-on-linux
- http://myonlineusb.wordpress.com/2011/06/19/how-to-convert-certificates-between-pem-der-p7bpkcs7-pfxpkcs12/
- https://www.sslshopper.com/article-most-common-openssl-commands.html
- https://github.com/ioerror/duraconf/blob/master/startssl/README.markdown#getting-a-free-certificate
- http://blog.brabeum.com/2011/08/securing-apache-for-free-with-ssl-and-startssl/
- https://www.startssl.com/?app=21
- https://konklone.com/post/switch-to-https-now-for-free
- https://www.globalsign.com/ssl/ssl-open-source/
- https://www.godaddy.com/ssl/ssl-open-source.aspx
- https://letsencrypt.org/
- http://www.cacert.org/
- https://www.sslshopper.com/article-free-ssl-certificates-from-a-free-certificate-authority.html
- https://gist.github.com/mnemonicflow/2477c773a59bb37f6564#ssl
- https://sethvargo.com/getting-an-a-plus-on-qualys-ssl-labs-tester/
- https://news.ycombinator.com/item?id=9141701
- https://gist.github.com/mnemonicflow/b5263f592a5583edaa6a784be36b7b13
openssl x509 -fingerprint -noout [-sha256] -in key.crt