Simple Port Scanner with Sockets





Now that we understand sockets, let's build a simple port-scanner. The idea of a port scanner is to run through a list of ports, testing to see if they are open. We can do this because the steps for using sockets for sending data is first you make the connection, then you try to off-load the request. Re-visiting our ship metaphor, the dock has no idea what contents are in the ship. Thus, if the port is open, the ship can at least dock before anyone knows whether or not what the ship is carrying is supposed to be there.

With our port scanner, we just attempt to dock at various ports, and do nothing else. If we're permitted to dock / connect to open ports, then we know at least the port is open. This is a form of "reconnaissance" for hackers and penetration testers.

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

target = input('What website to scan?: ')
		

Here is code you should recognize up to this point. For the target, you could enter website that allows you to do this. Check out "https://www.hackthissite.org/", or you can always target your own servers.

WARNING/DISCLAIMER:

It should be noted that port scanning can be seen as, or construed as, a crime. You should never execute a port scanner against any website or IP address without explicit, written, permission from the owner of the server or computer that you are targeting. Port scanning is akin to going to someones house and checking out all of their doors and windows. There is really only reason why anyone would do this, and it is to assess securities and vulnerabilities. Thus, if you have no good reason to be testing these things, it can be assumed you are a criminal.

Also, I have been locked out of my own servers before for running various penetration tests, which was part of the test. A lot of servers have security software that identifies and protects against things like port scans, slowing them down or just outright denying any further connections from the source IP address. Thus, you might find yourself unable to access a server after running a test. For this reason, you may want to use "https://www.hackthissite.org/" instead of just any random site, or even your own.

def pscan(port):
    try:
        con = s.connect((target,port))
        return True
    except:
        return False


for x in range(25):
    if pscan(x):
        print('Port',x,'is open')	    
	  

That's all, for a simple port scanner. What we've done above is simply attempt a connection to a port. If that is successful, our function returns a True, otherwise a False. If True is returned, then our little program will print out the successful port to the console.

The next tutorial:






  • Python Introduction
  • Print Function and Strings
  • Math with Python
  • Variables Python Tutorial
  • While Loop Python Tutorial
  • For Loop Python Tutorial
  • If Statement Python Tutorial
  • If Else Python Tutorial
  • If Elif Else Python Tutorial
  • Functions Python Tutorial
  • Function Parameters Python Tutorial
  • Function Parameter Defaults Python Tutorial
  • Global and Local Variables Python Tutorial
  • Installing Modules Python Tutorial
  • How to download and install Python Packages and Modules with Pip
  • Common Errors Python Tutorial
  • Writing to a File Python Tutorial
  • Appending Files Python Tutorial
  • Reading from Files Python Tutorial
  • Classes Python Tutorial
  • Frequently asked Questions Python Tutorial
  • Getting User Input Python Tutorial
  • Statistics Module Python Tutorial
  • Module import Syntax Python Tutorial
  • Making your own Modules Python Tutorial
  • Python Lists vs Tuples
  • List Manipulation Python Tutorial
  • Multi-dimensional lists Python Tutorial
  • Reading CSV files in Python
  • Try and Except Error handling Python Tutorial
  • Multi-Line printing Python Tutorial
  • Python dictionaries
  • Built in functions Python Tutorial
  • OS Module Python Tutorial
  • SYS module Python Tutorial
  • Python urllib tutorial for Accessing the Internet
  • Regular Expressions with re Python Tutorial
  • How to Parse a Website with regex and urllib Python Tutorial
  • Tkinter intro
  • Tkinter buttons
  • Tkinter event handling
  • Tkinter menu bar
  • Tkinter images, text, and conclusion
  • Threading module
  • CX_Freeze Python Tutorial
  • The Subprocess Module Python Tutorial
  • Matplotlib Crash Course Python Tutorial
  • Python ftplib Tutorial
  • Sockets with Python Intro
  • Simple Port Scanner with Sockets
  • Threaded Port Scanner
  • Binding and Listening with Sockets
  • Client Server System with Sockets
  • Python 2to3 for Converting Python 2 scripts to Python 3
  • Python Pickle Module for saving Objects by serialization
  • Eval Module with Python Tutorial
  • Exec with Python Tutorial