The complexity of modern distributions offers many potential attack vectors for malware. Lynis lets you find these vulnerabilities before an attacker does.
The most tedious part of supervised machine learning is providing sufficient supervision. However, if the samples come from a restricted sample space, unsupervised learning might be fine for the task.
If you want to learn a little bit more about the communication between a web browser and an HTTP server, why not build your own web server and take a closer look.