Internet & Cybersecurity Basics

🎯 Learning Objectives

• Understand the fundamental concepts of cybersecurity
• Learn how the Internet works at a basic level
• Recognize the difference between HTTP and HTTPS
• Identify common cybersecurity threats
• Apply basic security best practices

🛡️ What is Cybersecurity?

Cybersecurity is the practice of protecting computer systems, networks, and data from unauthorized access, attacks, theft, and damage. It encompasses a wide range of technologies, processes, and practices designed to safeguard digital assets.

🌐 How the Internet Works

The Internet is a global network of interconnected computers that communicate using standardized protocols. Understanding this foundation is crucial for cybersecurity.

# Example DNS lookup
nslookup example.com
Server:     8.8.8.8
Address:    8.8.8.8#53

Name:      example.com
Address:    93.184.216.34

SYN → (Client sends connection request)
SYN-ACK → (Server acknowledges)
ACK → (Client confirms)
→ Connection established!

GET /index.html HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0
Accept: text/html

🔐 HTTP vs HTTPS

Understanding the difference between HTTP and HTTPS is fundamental to web security.

🚨 Common Cybersecurity Threats

💻 Practical Examples

Secure Password Check (Python)

import hashlib
import secrets

def check_password(password: str, stored_hash: str, salt: str) -> bool:
    """Verify a password against a stored hash."""
    # Create hash with salt
    password_hash = hashlib.pbkdf2_hmac(
        'sha256',
        password.encode('utf-8'),
        salt.encode('utf-8'),
        100000  # Number of iterations
    )
    return password_hash.hex() == stored_hash

# Example usage
salt = secrets.token_hex(16)
password = "MySecureP@ssw0rd!"
password_hash = hashlib.pbkdf2_hmac(
    'sha256',
    password.encode('utf-8'),
    salt.encode('utf-8'),
    100000
).hex()

print(f"Salt: {salt}")
print(f"Hash: {password_hash}")

Basic HTTPS Check (Python)

import ssl
import socket

def check_https(domain: str) -> dict:
    """Check if a domain supports HTTPS."""
    result = {
        'domain': domain,
        'https_supported': False,
        'ssl_grade': None,
        'error': None
    }
    
    try:
        # Create SSL context
        context = ssl.create_default_context()
        
        # Connect to the server
        with socket.create_connection((domain, 443), timeout=10) as sock:
            with context.wrap_socket(sock, server_hostname=domain) as ssock:
                result['https_supported'] = True
                result['ssl_grade'] = ssock.version()
                result['cipher'] = ssock.cipher()
                
    except Exception as e:
        result['error'] = str(e)
    
    return result

# Check example.com
check = check_https("example.com")
print(check)

🎯 Mini Project: Secure Login Interface

Create a secure login form with HTML5 security features:

    
    
    
    
    Email:
    
    
    
    Password:
    
    
    
    
    Remember this device
    
    Secure Login

🏋️ Practice Challenge

📝 Summary