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

SSH authentication

SSH provides authentication methods for both the server (host) and the client (user). It should be obvious why the server must authenticate the client. The server wants to only provide access to authorized users. Otherwise, anyone could take over the server.

However, the client also needs to authenticate the server. If the client fails to authenticate the server properly, then the client could be tricked into sending its password to an impostor!

In SSH, servers are authenticated using public key encryption. Conceptually, this is very similar to how HTTPS provides server authentication. However, SSH doesn't typically rely on certificate authorities. Instead, when using SSH, most clients simply keep a list of the public keys (or hashes of the public keys) that they trust. How the clients obtain this list in the first place varies. Generally, if a client connects to a server under trusted circumstances, then it can trust that public key in the future too.

libssh implements features...