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

Email servers

SMTP is the protocol responsible for delivering emails between servers. It is a text-based protocol operating on TCP port 25.

Not all emails need to be delivered between systems. For example, imagine you have a Gmail account. If you compose and send an email to your friend who also has a Gmail account, then SMTP is not necessarily used. In this case, Gmail only needs to copy your email into their inbox (or do equivalent database updates).

On the other hand, consider a case where you send an email to your friend's Yahoo! account. If the email is sent from your Gmail account, then it's clear that the Gmail and Yahoo! servers must communicate. In that case, your email is transmitted from the Gmail server to the Yahoo! server using SMTP.

This connection is illustrated in the following diagram:

Retrieving your email from your mail service provider is a different issue than delivering email between service providers. Webmail is very popular now for sending and receiving mail from your...