CyberSecurity & DevSecOps Expert: Develop, PenTest, and Deploy Secure Applications

Up to this point in the course, you have been writing Python code using variables, conditions, and loops. You have tested your scripts interactively or by running simple files. Now it is time to take a step further: writing Python scripts that can be...

**Theoretical Recap** A `while` loop repeats a block of code as long as a given condition remains True. Unlike a `for` loop — which iterates over a known sequence — a `while` loop is ideal when you do not know in advance how many iterations are neede...

**Theoretical Recap** A `for` loop in Python iterates over a sequence — a range of numbers, a list, or any iterable object — and executes a block of code for each element. The built-in `range()` function is essential here: `range(start, stop, step)` ...

In the previous activities, you learned how to declare variables, convert types, and make decisions using if/else conditions. You now know how to write a Python script that reacts differently depending on a value. But what happens when you need to re...

**Theoretical Recap** In networking, ports are numerical identifiers ranging from 0 to 65535 that allow operating systems to route incoming and outgoing traffic to the correct process or service. Ports below 1024 are called 'well-known' or 'reserved'...

In the previous activities, you learned how to declare variables, assign values to them, and perform basic type conversions. You now have the building blocks to store information in your Python scripts. However, a script that always executes the same...

**Theoretical Recap** In Python, every value has a type: int (integer), float (decimal number), str (string of characters), bool (True/False). In real-world security scripting, data rarely arrives in the format you need. A port number read from a fil...

**Theoretical Recap** In Python, a variable is a named container that stores a value in memory. Unlike languages such as C or Java, Python is dynamically typed: you do not need to explicitly declare the type of a variable before assigning a value to ...

Variables and data types are the absolute foundation of any Python program. Before writing any security automation script — whether to scan a network, parse HTTP responses, or manipulate file contents — you must understand how Python stores, names, a...

When working with Python, especially in a cybersecurity or automation context, one of the first professional habits to adopt is the use of virtual environments. This chapter explains what a virtual environment is, why it is essential, and how to crea...

Before writing a single line of Python code for security automation, you need a properly configured work environment. This chapter covers the essential steps: installing Python, choosing and setting up a code editor, creating isolated project environ...

Welcome to the chapter on Python programming basics for security automation. This chapter is designed specifically for beginners who are entering the field of cybersecurity and DevSecOps, and who want to use Python as a practical tool to automate sec...

This concluding chapter serves as a structured review of everything covered throughout the 'Fundamentals of OSI networks, protocols and models' section. It is designed to consolidate your understanding, identify any remaining gaps, and confirm that y...

At this stage of the course, you have covered a rich and dense set of topics: from the Open Systems Interconnection model and its seven layers, to the Address Resolution Protocol and the Dynamic Host Configuration Protocol, the Network Address Transl...

## Project Overview This mini-project is the capstone activity for the 'Fundamentals of OSI Networks, Protocols and Models' chapter. You will produce a fully annotated diagram tracing the complete lifecycle of an HTTP request — from the moment a user...

**Theoretical Recap** HTTP (HyperText Transfer Protocol) operates at Layer 7 (Application) of the OSI model, sitting on top of TCP (Layer 4), IP (Layer 3), and ultimately Ethernet (Layer 2). When a browser sends an HTTP request, it first establishes ...

In the previous activities, you explored the lower layers of the OSI model: the physical layer, the data link layer, the network layer (with IP addressing, routing tables, and subnetting), and you practiced with Network Address Translation and Domain...

**Theoretical Recap** The hosts file is one of the oldest name resolution mechanisms in computing, predating DNS entirely. Located at `/etc/hosts` on Linux/macOS and `C:\Windows\System32\drivers\etc\hosts` on Windows, it acts as a local, static looku...

**Theoretical Recap** DNS (Domain Name System) is the internet's phone book: it translates human-readable hostnames (e.g., example.com) into IP addresses that routers and hosts can use. A DNS lookup follows a strict hierarchical resolution chain: you...

DNS, which stands for Domain Name System, is one of the most fundamental protocols of the modern internet. Without it, users would need to memorize the numerical IP addresses of every website or service they want to reach. Instead, DNS allows the use...

**Theoretical Recap** Network Address Translation (NAT) is a mechanism that rewrites IP headers at the boundary between a private network and the public internet. When a packet leaves your LAN, the router replaces the source private IP (e.g., 192.168...

Network Address Translation, commonly abbreviated as NAT, is a mechanism that allows one or more private IP addresses to be mapped to one or more public IP addresses. It operates at the boundary between a private network (such as a home or corporate ...

Understanding how network connections are tracked and how firewalls make decisions about traffic is a foundational skill for any cybersecurity professional. In the previous activities, you explored how TCP handshakes work, how to capture and filter t...

**Theoretical Recap** A routing table is a data structure stored in the kernel of an operating system that determines how network packets are forwarded from one network interface to another. Every Linux machine — whether a workstation, server, or vir...

Routing is one of the most fundamental mechanisms in computer networking. It is the process by which data packets travel from one network to another until they reach their destination. Understanding how routing works is essential for anyone entering ...