Book excerpt: Transport Layer Security, or TLS, makes ecommerce and online banking possible. It protects your passwords and your privacy. Let’s Encrypt transformed TLS from an expensive tool to a free one. TLS understanding and debugging is an essential sysadmin skill you must have. TLS Mastery takes you through: · How TLS works · What TLS provides, and what it doesn’t · Wrapping unencrypted connections inside TLS · Assessing TLS configurations · The Automated Certificate Management Environment (ACME) protocol · Using Let’s Encrypt to automatically maintain TLS certificates · Online Certificate Status Protocol · Certificate Revocation · CAA, HSTS, and Certificate Transparency · Why you shouldn’t run your own CA, and how to do it anyway · and more! Stop wandering blindly around TLS. Master the protocol with TLS Mastery!