Making a Port-Scanner in Kali Linux Terminal Using Python

In computer networking, a port is a virtual point where network connections start and end. It’s like an open door of your home, If you don’t close this then anyone can Enter your home. A port scanner is a program that is searching ports in a network and tries to find which ports are virtually open and close. It is common technique hackers or cyber-security experts used to discover open doors or weak points in a network. 

How Does a Port Scanner Program Work?

This program sends a network request throw network and tries to connect to a specific TCP or UDP port on a computer and records the response.

The three types of responses are below:

1. Open, Accepted: When ports are open, and you can access this system by them.
2. Closed, Not Listening: When this port is in use or unavailable at this time
3. Filtered, Dropped, Blocked: The computer doesn’t even bother to respond.

 Design a Port Scanner on Kali Linux Terminal Using Python 

Step 1: Design a Program 

At the very first we need to open Our Kali Linux terminal and the very first thing that we should do is find out where our python interpreter is so we command

Syntax:

which python

where is our python interpreter

That’s going to be important when we do this very next step. 

Next step we need to open the shell because in there we are going to type our code, so we can type nano command and hit enter.

Syntax: 

nano (name).extension

Example: 

nano port-scanner.py

give our program a name 

Now In here at first we need to assign our Python interpreter Location

#!//usr/bin/python

location of Python interpreter 

Now our main program start, we want to import sockets, sockets will tell us the ports how to operate and essentially how to transmit data.

import socket

Then we need to input IP addresses  and after that, we also need a program to ask for which port we are looking for

ip = raw_input("enter the IP Address: ")
port = input("Enter the Port Number: ")

Now we want to Define the socket what type of transmitted data are we are looking for to be more specific what Protocol are we asking for to see.

• socket.AF_INET this socket allows us to see TCP connection
• SOCK_STREAM  this allows us to look at UDP protocol that’s  essentially streaming video and audio

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

Now we are going to print how our program shows us if the specific port open or either IP is down or The port is closed.

if sock.connect_ex((ip,port)):
       print "Port ",port, "is closed"
else:
         print"Port",port,"is OPEN"

full program 

Now save this program press control key + x key to save this program

Syntax: 

cnrl+x

Step 2: Compile and Run The program 

We all Know How to Run a Script on the Kali Linux terminal 

Example 

./script name . extension

Syntax

./port-scanner.py

Program Didn’t Run 

Look here is the tricky part, We write Our program Perfectly, but it’s Not compiled and Run. So It’s time to give our System Permission. 

Chmod 775  is a Linux command which sets  permission so that  User/Owner can Read, Write and execute. Group can Read  Write and execute. Others can Read But can’t Write and execute. 

Syntax

chmod 775 ./port-scanner.py

chmod 775 gives you permission 

Now we can Run Our program again, and it will compile and Run Successfully 

Syntax 

./port-scanner.py

Run successfully 

Test Our program 

So for port scanning, We need a specific IP, and we need to Tell Our Program which port we are Looking For  after Input Hit Enter 

Example 

Enter Your Ip Address : 192.168.43.1
Enter The Port Number : 80

Port scanning Successfully 

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Article Tags :

• Computer Networks
• Linux-Unix
• Python
• Python Programs
• Kali-Linux

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Practice Tags :

• python