Securing network applications

In the previous section of this book, we designed a network application that receives client data using socket connections. Besides the fact that most viruses that penetrate the system are from the outside world, network applications have this natural tendency to open the computer to various threats on the internet. First, an open port exists when running a network application. Someone who knows the same port your application listens to can intrude by faking protocol data. We will mostly discuss the server side of network applications here; however, some topics also apply to client applications.

One of the first things you should do is incorporate client authorization and authentication. These are two terms that are easy to confuse. Be careful not to use them interchangeably; they are different, as detailed here:

• Authentication is the process of validating client access. This means that not every incoming connection request is served right away...