Introduction to Linux Security Fundamentals

Welcome, Operator!

You're about to enter a fully configured Kali Linux environment - the same operating system used by professional penetration testers and security researchers worldwide.

Your First Steps:

1. Click "Start Machine" above to launch your lab environment
2. Wait for the desktop to fully load (usually 30-60 seconds)
3. Open a terminal by clicking the terminal icon in the taskbar or pressing Ctrl+Alt+T

Once your terminal is open, you're ready to continue to the next task!

Who Are You?

In Linux, every action is performed by a user. Understanding user permissions is fundamental to both system administration and hacking.

The whoami command tells you your current username. Try it now!

Key User Types in Linux:

Your Task:

Run the whoami command in your terminal and enter the username below:

The Linux File System

Unlike Windows with its drive letters (C:, D:), Linux has a single hierarchical file system starting from / (root).

Essential Navigation Commands:

pwd     # Print Working Directory - where am I?
ls      # List files in current directory
ls -la  # List ALL files with details (including hidden)
cd /    # Change to root directory
cd ~    # Change to home directory (~ is shortcut)
cd ..   # Go up one directory

Your Task:

Navigate to your home directory using cd ~, then use pwd to find the full path. Enter it below:

Understanding Permission Strings

When you run ls -la, you'll see something like this:

-rwxr-xr-x  1 kali kali  4096 Jan 15 10:30 script.sh
drwxr-xr-x  2 kali kali  4096 Jan 15 10:30 Documents
-rw-------  1 root root  1679 Jan 15 10:30 secret.key

Breaking Down Permissions:

Permission Values:

• r (read = 4) - View file contents or list directory
• w (write = 2) - Modify file or create/delete in directory
• x (execute = 1) - Run as program or enter directory

Try running ls -la /etc/passwd to see the permissions on a critical system file.

Your First Reconnaissance

Nmap (Network Mapper) is the most essential tool in any hacker's arsenal. It's used to discover hosts, services, and vulnerabilities on networks.

Basic Nmap Commands:

# Ping scan - check if host is alive
nmap -sn 127.0.0.1

# Quick port scan
nmap 127.0.0.1

# Service version detection
nmap -sV 127.0.0.1

# Operating system detection (requires root)
sudo nmap -O 127.0.0.1

Your Task:

Run a ping scan on localhost:

nmap -sn 127.0.0.1

Look at the output. What status does it show for the host? (Hint: it's a 2-letter word)

🚀 Next Steps: