chapter-17-python-scripting-basics-for-hackers.md

Chapter 17: Python Scripting Basics for Hackers

Overview

Python is a versatile programming language that is widely used in cybersecurity for automation, penetration testing, and creating custom tools. This chapter introduces Python basics and demonstrates how to use it for hacking-related tasks.

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1. Introduction to Python

Key Features:

• Easy to learn and use.
• Extensive libraries for networking, cryptography, and data manipulation.
• Cross-platform compatibility.

Installing Python:

• Most Linux distributions come with Python pre-installed. To check:

  python3 --version
• Install Python if not present:

  sudo apt install python3
  sudo apt install python3-pip

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2. Writing and Running Python Scripts

Writing a Script:

1. Create a file with the .py extension (e.g., script.py).
2. Write your Python code.

Running a Script:

python3 script.py

Example Script:

#!/usr/bin/env python3

print("Hello, World!")

Make the script executable:

chmod +x script.py
./script.py

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3. Python Basics

Variables:

name = "Hacker"
age = 25
print(f"Name: {name}, Age: {age}")

Conditional Statements:

if age > 18:
    print("Adult")
else:
    print("Minor")

Loops:

for i in range(5):
    print(i)

count = 0
while count < 5:
    print(count)
    count += 1

Functions:

def greet(name):
    return f"Hello, {name}!"

print(greet("Hacker"))

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4. Networking with Python

Using socket:

• Create a simple TCP client:

import socket

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(("127.0.0.1", 8080))
client.send(b"Hello, Server!")
data = client.recv(1024)
print(f"Received: {data.decode()}")
client.close()

• Create a simple TCP server:

import socket

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(("0.0.0.0", 8080))
server.listen(5)

print("Server listening...")
while True:
    client, addr = server.accept()
    print(f"Connection from {addr}")
    client.send(b"Hello, Client!")
    client.close()

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5. File Handling

Reading and Writing Files:

# Write to a file
with open("output.txt", "w") as file:
    file.write("Hello, File!")

# Read from a file
with open("output.txt", "r") as file:
    print(file.read())

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6. Automating Tasks

Web Scraping with requests and BeautifulSoup:

• Install the libraries:

  pip3 install requests beautifulsoup4

• Example:

import requests
from bs4 import BeautifulSoup

response = requests.get("http://example.com")
soup = BeautifulSoup(response.text, "html.parser")
print(soup.title.string)

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7. Working with APIs

Example: Fetching Data from a Public API:

import requests

url = "https://api.github.com"
response = requests.get(url)
print(response.json())

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8. Cryptography with Python

Using the cryptography Library:

• Install the library:

  pip3 install cryptography

• Example:

from cryptography.fernet import Fernet

# Generate a key
key = Fernet.generate_key()
cipher = Fernet(key)

# Encrypt data
data = b"Secret Message"
encrypted = cipher.encrypt(data)
print(f"Encrypted: {encrypted}")

# Decrypt data
decrypted = cipher.decrypt(encrypted)
print(f"Decrypted: {decrypted.decode()}")

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9. Error Handling

Try-Except Blocks:

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")

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Summary

By the end of this chapter, you should be able to:

• Write and execute basic Python scripts.
• Use Python for networking, file handling, and automation.
• Perform web scraping and interact with APIs.
• Implement cryptography for secure data handling.

Next Steps:

• Explore advanced scripting concepts and integrate Python with tools like Metasploit.
• Move to Excercises to test your Python and cybersecurity skills.

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Exercises

1. Write a Python script that scans a range of IP addresses for open ports.
2. Automate downloading a file from a URL and save it locally.
3. Create a script that encrypts and decrypts text using cryptography.
4. Use requests to fetch and display the latest news headlines from an API.
5. Build a simple chat application using Python sockets.