Book Image

Hands-On Network Programming with C

By : Lewis Van Winkle
Book Image

Hands-On Network Programming with C

By: Lewis Van Winkle

Overview of this book

Network programming enables processes to communicate with each other over a computer network, but it is a complex task that requires programming with multiple libraries and protocols. With its support for third-party libraries and structured documentation, C is an ideal language to write network programs. Complete with step-by-step explanations of essential concepts and practical examples, this C network programming book begins with the fundamentals of Internet Protocol, TCP, and UDP. You’ll explore client-server and peer-to-peer models for information sharing and connectivity with remote computers. The book will also cover HTTP and HTTPS for communicating between your browser and website, and delve into hostname resolution with DNS, which is crucial to the functioning of the modern web. As you advance, you’ll gain insights into asynchronous socket programming and streams, and explore debugging and error handling. Finally, you’ll study network monitoring and implement security best practices. By the end of this book, you’ll have experience of working with client-server applications and be able to implement new network programs in C. The code in this book is compatible with the older C99 version as well as the latest C18 and C++17 standards. You’ll work with robust, reliable, and secure code that is portable across operating systems, including Winsock sockets for Windows and POSIX sockets for Linux and macOS.
Table of Contents (26 chapters)
Title Page
About Packt

The SSH protocol

Most servers providing a service (such as websites and emails) over the modern internet aren't attached to keyboards or monitors. Even when servers do have local input/output hardware, remote access is often much more convenient.

Various protocols have been used to provide remote command-line access to servers. One of the first such protocols was Telnet. With Telnet, a client remotely connects to a server using plaintext over TCP port 23. The server provides more-or-less direct access to the operating system command-line through this Transmission Control Protocol (TCP) connection. The client sends plaintext commands to the server, and the server executes these commands. The command-line output is sent back from the server to the client.

Telnet has a major security shortcoming: it does not encrypt any data sent over the network. Even user passwords are sent as plaintext when using Telnet. This means that any network eavesdropper could obtain user credentials!

The SSH protocol...