When it comes to creating powerful and effec tive hacking tools, Python is the language of

Code Hygiene

No matter what you use to write your programs, it is a good idea to follow a 

code-formatting guideline. A code style guide provides recommendations to 

improve the readability and consistency of your Python code. It makes it eas-

ier for you to understand your own code when you read it later or for others if 

Black Hat Python (Early Access) © 2021 by Justin Seitz and Tim Arnold

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6

   

Chapter 1

you decide to share it. The Python community has a such a guideline, called 

PEP 8. You can read the full PEP 8 guide here: https://www.python.org/dev/peps/

pep-0008/.

The examples in this book generally follow PEP 8, with a few differ-

ences. You’ll see that the code in this book follows a pattern like this:

1 from lxml import etree

from subprocess import Popen

2 import argparse

import os

3 def get_ip(machine_name):  

    pass  

4 class Scanner:

    def __init__(self):

        pass

5 if __name__ == '__main__':

    scan = Scanner()

    print('hello')

At the top of our program, we import the packages we need. The first 

import block 1 is in the form of 

from

 

XXX import YYY

 type. Each import line 

is in alphabetical order.

The same holds true for the module imports—they, too, are in alphabet-

ical order 2. This ordering lets you see at a glance whether you’ve imported a 

package without reading every line of imports, and it ensures that you don’t 

import a package twice. The intent is to keep your code clean and lessen the 

amount you have to think when you reread your code.

Next come the functions 3, then class definitions 4, if you have any. 

Some coders prefer to never have classes and rely only on functions. There’s 

no hard-and-fast rule here, but if you find you’re trying to maintain state 

with global variables or passing the same data structures to several func-

tions, that may be an indication that your program would be easier to 

understand if you refactor it to use a class.

Finally, the main block at the bottom 5 gives you the opportunity to use 

your code in two ways. First, you can use it from the command line. In this 

case, the module’s internal name is 

__main__

 and the main block is executed. 

For example, if the name of the file containing the code is scan.py, you could 

invoke it from the command line as follows:

python scan.py

This will load the functions and classes in scan.py and execute the main 

block. You would see the response 

hello

 on the console.

Second, you can import your code into another program with no side 

effects. For example, you would import the code with

import scan

Black Hat Python (Early Access) © 2021 by Justin Seitz and Tim Arnold

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Setting Up Your Python Environment

   

7

Since its internal name is the name of the Python module, 

scan

, and not 

__main__

, you have access to all the module’s defined functions and classes, 

but the main block is not executed.

You’ll also notice we avoid variables with generic names. The better 

you get at naming your variables, the easier it will be to understand the 

program.

You should have a virtual machine, Python 3, a virtual environment, 

and an IDE. Now let’s get into some actual fun!

Black Hat Python (Early Access) © 2021 by Justin Seitz and Tim Arnold

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Black Hat Python (Early Access) © 2021 by Justin Seitz and Tim Arnold

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