Establishing TLS Connections and Sending Data over Them

In this chapter, we will learn about the Transport Layer Security (TLS) protocol. The TLS protocol is the successor of the Secure Sockets Layer (SSL) protocol and is used for secure network communication and serves as the basis for higher-level protocols, such as Hypertext Transfer Protocol Secure (HTTPS) and Simple Mail Transfer Protocol Secure (SMTPS). The TLS protocol is most visible on the World Wide Web but is also used in other applications, such as file transfer, email, instant messaging, Voice over IP, remote access, connection to databases, financial data transmission, and many other applications that require encrypted communication.

We will learn about the basics of the TLS protocol and take a quick look at its history. In the practical part of this chapter, we will learn how to establish TLS connections, send data over them, and shut them down correctly. There will be both command-line and C code examples that illustrate...