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

Installing OpenSSL

Assuming you already have Homebrew installed, installing OpenSSL is easy.

Open a new Terminal window and use the following command to install the OpenSSL library:

brew install [email protected]

At the time of writing, the default Homebrew openssl package is outdated, therefore we'll use the [email protected] package instead.

The following screenshot shows Homebrew installing the [email protected] package:

Be sure to read any output from brew.

The method suggested by the brew command has you pass -L and -I to the compiler to tell it where to locate the OpenSSL libraries. This is tedious.

You may prefer to symlink the installed library files to the /usr/local path so that your compiler can find them automatically. Whether you want to do this or not is up to you.

If you want to create symlinks so the compiler can find OpenSSL, try the following commands:

cd /usr/local/include
ln -s ../opt/[email protected]/include/openssl .
cd /usr/local/lib
for i in ../opt/[email protected]/lib/lib*; do ln -vs $i .; done

This is shown in the following screenshot:

You can try building openssl_version.c from Chapter 9Loading Secure Web Pages with HTTPS and OpenSSL, to test that everything is installed correctly. It should look like the following: