In this MOOC, we will learn the basic cyber security concepts, how to identify vulnerabilities/threat in a network system. We will apply CIA basic security services in the triage of recent cyberattack incidents, such as OPM data breach. We will learn the risk management framework for analyzing the risks in a network system, and apply the basic security design principles to protect the data and secure computer systems. We will examine the trustworthiness of programs and data installed in our systems and show the proper way to verify their integrity and authenticity. We will apply principle of least privileges for controlling the shared access given to different groups of users and system processes. On Amazon Cloud instances, we will use GnuPG software to generate public/private key pair for signing/verifying documents and open source software, and for encrypting documents. We will learn how to publish software, the related signature and release key on web server and publish public key to PGP key server for others to retrieve. We will learn Public Key Infrastructure (PKI) and Linux utility to serve as a CA for an organization, learn how to sign certificate request for clients or servers in secure email and web applications.