Cybersecurity protects systems, networks, and data from attacks.

Ethical hacking involves legally testing systems for security weaknesses.

Python is widely used in cybersecurity because it is:

• Easy to learn
• Powerful
• Rich in networking libraries
• Excellent for automation

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Important Note

Ethical hacking should only be performed:

• On systems you own
• With proper authorization

Unauthorized hacking is illegal.

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Python in Cybersecurity

Python is used for:

• Network scanning
• Packet analysis
• Password auditing
• Automation tools
• Security testing

Popular libraries:

• socket
• scapy
• cryptography
• requests

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Network Scanning

Network scanning identifies:

• Active devices
• Open ports
• Running services

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Using socket

Python provides:

socket

module for network communication.

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Simple Port Scanner

import socket

target = "127.0.0.1"

for port in range(1, 101):

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

    result = sock.connect_ex(
        (target, port)
    )

    if result == 0:
        print(f"Port {port} is open")

    sock.close()

---

Scan Specific Port

import socket

host = "google.com"
port = 80

sock = socket.socket()

result = sock.connect_ex(
    (host, port)
)

if result == 0:
    print("Port open")
else:
    print("Port closed")

sock.close()

---

Banner Grabbing

Used to identify running services.

import socket

sock = socket.socket()

sock.connect(("example.com", 80))

sock.send(b"HEAD / HTTP/1.1\r\n\r\n")

banner = sock.recv(1024)

print(banner.decode())

sock.close()

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Packet Sniffing

Packet sniffing captures network packets.

Used for:

• Traffic analysis
• Security monitoring
• Network debugging

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Scapy Library

Install:

pip install scapy

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Capture Packets

from scapy.all import sniff

def packet_callback(packet):
    print(packet.summary())

sniff(count=5, prn=packet_callback)

---

Filter TCP Packets

from scapy.all import sniff

sniff(
    filter="tcp",
    count=10,
    prn=lambda p: p.summary()
)

---

View Packet Details

from scapy.all import sniff

packet = sniff(count=1)[0]

packet.show()

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Cryptography Basics

Cryptography secures data using encryption.

Main concepts:

• Encryption
• Decryption
• Hashing

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Symmetric Encryption

Same key used for:

• Encryption
• Decryption

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Install Cryptography Library

pip install cryptography

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Generate Encryption Key

from cryptography.fernet import Fernet

key = Fernet.generate_key()

print(key)

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Encrypt Data

from cryptography.fernet import Fernet

key = Fernet.generate_key()

cipher = Fernet(key)

message = b"Python Security"

encrypted = cipher.encrypt(message)

print(encrypted)

---

Decrypt Data

decrypted = cipher.decrypt(encrypted)

print(decrypted.decode())

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Hashing

Hashing converts data into fixed-length output.

Used for:

• Password storage
• Integrity verification

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SHA256 Hash Example

import hashlib

text = "password123"

hash_value = hashlib.sha256(
    text.encode()
).hexdigest()

print(hash_value)

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Password Checker Example

import hashlib

password = input("Enter password: ")

hashed = hashlib.sha256(
    password.encode()
).hexdigest()

print("Hash:", hashed)

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Automation Tools

Python can automate security-related tasks.

Examples:

• Log monitoring
• File scanning
• Vulnerability checks

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File Integrity Checker

import hashlib

def calculate_hash(filename):

    sha256 = hashlib.sha256()

    with open(filename, "rb") as file:

        while chunk := file.read(4096):

            sha256.update(chunk)

    return sha256.hexdigest()

print(calculate_hash("data.txt"))

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Automated Website Status Checker

import requests

websites = [
    "https://google.com",
    "https://github.com"
]

for site in websites:

    try:

        response = requests.get(site)

        print(
            site,
            response.status_code
        )

    except Exception as e:

        print(site, "Error")

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Simple Keylogger Warning

Keyloggers capture keyboard input and can be illegal or harmful.

They should only be studied in controlled ethical environments.

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Network Monitoring Tool

import psutil

network = psutil.net_io_counters()

print("Bytes Sent:", network.bytes_sent)

print("Bytes Received:", network.bytes_recv)

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WHOIS Lookup Example

import socket

domain = "example.com"

ip = socket.gethostbyname(domain)

print("IP Address:", ip)

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Practical Example

Simple Network Scanner

import socket

target = input("Enter IP: ")

start_port = 1
end_port = 100

for port in range(
    start_port,
    end_port + 1
):

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

    sock.settimeout(0.5)

    result = sock.connect_ex(
        (target, port)
    )

    if result == 0:
        print(f"Port {port} open")

    sock.close()

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Advantages of Python in Cybersecurity

✅ Easy scripting
✅ Strong networking support
✅ Excellent automation
✅ Large security libraries
✅ Fast development

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Best Practices

✅ Always get permission before testing
✅ Use ethical hacking responsibly
✅ Keep tools updated
✅ Secure sensitive data
✅ Avoid illegal activities

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Summary

In this chapter you learned:

✅ Network scanning
✅ Packet sniffing
✅ Cryptography basics
✅ Hashing and encryption
✅ Automation tools in cybersecurity