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Itm U4

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11 views41 pages

Itm U4

Uploaded by

jairajput2582563
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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What Are Web Servers?

A web server is a computer program or system that delivers


web pages to users over the internet. It stores, processes,
and sends website files (like HTML, images, videos, etc.) to
people who request them using a browser such as Google
Chrome, Mozilla Firefox, or Safari.
When you type a website address (like www.google.com) into
your browser and press Enter, the browser sends a request to
the web server. The web server receives this request, finds
the correct web page on its storage, and sends it back to your
browser so that you can see and interact with the website.
Web servers use a communica on rule called HTTP
(HyperText Transfer Protocol) or HTTPS (secure version) to
handle these requests and responses. This is why you o en
see "h p://" or "h ps://" before a website address.
Web servers can be of two types:
1. Hardware (Physical machine): A powerful computer that
stores website files and stays connected to the internet.
2. So ware (Program): An applica on that handles
incoming web requests and sends out responses.
Some popular web server so ware are:
 Apache HTTP Server
 Nginx
 Microso IIS
 LiteSpeed
Each has different features, but they all do the same basic
job: serving web pages to users.

Using Apache HTTP Server


One of the most widely used web servers in the world is the
Apache HTTP Server, also called Apache. It is free, open-
source, and works on almost all opera ng systems like
Windows, Linux, and macOS. It is very popular among
students, developers, and companies.
Steps to Access and Use Apache Web Server
Let’s understand how we can install and use Apache on a
computer for hos ng a simple website.

1. Installing Apache
On Windows:
Apache is not installed by default on Windows, so we use a
so ware bundle like XAMPP which includes Apache, PHP, and
MySQL.
Steps:
 Go to h ps://www.apachefriends.org
 Download XAMPP and install it.
 A er installing, open XAMPP Control Panel
 Click Start next to “Apache”
This will start the Apache server on your computer.
On Linux (like Ubuntu):
You can install Apache directly using terminal commands:
bash
Copy code
sudo apt update
sudo apt install apache2
Once installed, start the server:
bash
Copy code
sudo systemctl start apache2

2. Tes ng Apache Server


A er star ng the Apache server, open a web browser and
type:
arduino
Copy code
h p://localhost
If everything is working, you will see a welcome page or
message like “It works!” This means Apache is running and
ready.

3. Crea ng a Simple Website


Apache uses a folder to store website files. This folder is
called the Document Root.
 On Windows (with XAMPP):
Folder path is C:\xampp\htdocs
 On Linux (Ubuntu):
Folder path is /var/www/html
Steps to host a website:
 Go to the document root folder
 Create a new file named index.html
 Write the following HTML code:
html
Copy code
<!DOCTYPE html>
<html>
<head>
< tle>My Website</ tle>
</head>
<body>
<h1>Welcome to My First Website</h1>
</body>
</html>
 Save the file
 Open your browser and go to h p://localhost
You will now see your website’s homepage.

4. Apache Configura on Files


Apache has se ngs that control how it works. These se ngs
are wri en in special configura on files.
 On Linux: Main file is /etc/apache2/apache2.conf
 On Windows (XAMPP): Apache config file is in
C:\xampp\apache\conf\h pd.conf
Using these files, we can:
 Set which folder is used for website files
 Change the port number
 Set up different websites using Virtual Hosts
Example of a Virtual Host (for advanced use):
apache
Copy code
<VirtualHost *:80>
ServerName mysite.local
DocumentRoot /var/www/mysite
</VirtualHost>
This lets us run mul ple websites from one server.

5. Apache Modules
Apache can use modules to add extra features.
Some useful modules are:
 mod_rewrite: For clean URLs
 mod_ssl: For using HTTPS
 mod_security: For security and filtering
To enable a module on Linux:
bash
Copy code
sudo a2enmod rewrite
sudo systemctl restart apache2
On Windows (XAMPP), modules can be enabled in the
Apache config file or using the XAMPP Control Panel.

6. Securing Apache
It is important to make the web server safe from hackers.
Here are some simple ps:
 Use HTTPS by installing an SSL cer ficate (e.g., from Let’s
Encrypt)
 Do not allow directory browsing
 Keep Apache so ware up to date
 Use strong passwords for server access
 Use .htaccess files to control who can access certain
folders
.htaccess example to deny access:
css
Copy code
Order deny,allow
Deny from all
This code blocks all visitors from accessing that folder.

Apache is a powerful and flexible web server that is easy to


use for both beginners and professionals. With just a few
steps, you can install it, host a website, and make it accessible
from your computer or over the internet.
An Intrusion Detec on System (IDS) is a security tool used to
detect unauthorized access or suspicious ac vi es in a
computer system or network. The main purpose of IDS is to
monitor network traffic or system behavior to iden fy
threats, a acks, or security policy viola ons.
In simple terms, IDS works like a security guard for a
computer system. It keeps an eye on what is happening and
alerts the user or administrator if it no ces something
unusual or harmful.
There are two main types of IDS:
1. Network-based IDS (NIDS):
o Monitors data coming in and going out of the
network.
o Detects a acks like Denial of Service (DoS), port
scanning, or malware.
2. Host-based IDS (HIDS):
o Monitors a specific computer or device.
o Checks system files, log files, and user ac vity for
suspicious changes.
The key purposes of an IDS include:
 Threat Detec on: It helps iden fy cyber-a acks such as
viruses, worms, trojans, and hacking a empts.
 Alert Genera on: When an a ack is detected, the IDS
sends an alert to the system administrator for ac on.
 Policy Monitoring: IDS checks whether the users and
systems are following the security rules.
 Evidence Collec on: It records informa on about
a acks, which can be used for inves ga on or legal
ac ons.
 System Health Monitoring: It can detect internal
problems like so ware errors or misconfigura ons.
An IDS does not block a acks directly (that is the job of a
firewall), but it helps in early detec on, which is very
important for protec ng data and maintaining system
security.
1. Digital Signature
A Digital Signature is an electronic form of a signature that is
used to verify the authen city, integrity, and non-
repudia on of digital messages or documents. It ensures that
the message was created by a known sender and that it has
not been changed in transit.
Digital signatures are based on public key cryptography (also
known as asymmetric encryp on). This system uses a pair of
keys: a private key (kept secret by the sender) and a public
key (shared with everyone). The sender signs a document
using their private key, and anyone can verify it using the
sender’s public key.
Steps in digital signing:
1. A hash (mathema cal summary) of the document is
created.
2. The hash is encrypted using the sender’s private key.
3. This encrypted hash becomes the digital signature and is
a ached to the document.
4. The receiver uses the sender’s public key to decrypt the
signature and compare the hash to verify the content.
Uses of digital signatures:
 Signing emails, PDFs, so ware, and online forms.
 Securing online transac ons and contracts.
 Ensuring data is not tampered with.
Benefits:
 Ensures data integrity.
 Confirms the iden ty of the sender.
 Provides legal validity in many countries (e.g., under the
IT Act in India).
Limita ons:
 Requires a trusted Cer ficate Authority (CA) to issue
digital cer ficates.
 Loss of private key may cause issues with verifica on.
Digital signatures are widely used in e-governance, banking,
e-commerce, and secure communica ons. They are a key
part of cybersecurity and digital trust.

2. Firewalls
A Firewall is a security system that controls the incoming and
outgoing network traffic based on pre-defined rules. It acts as
a barrier between a trusted network (like a private LAN) and
an untrusted network (like the internet).
Firewalls are used to block unauthorized access and allow
safe communica on. They monitor data packets and decide
whether to allow or block them based on security rules.
Types of firewalls:
1. Hardware Firewall – A physical device that filters traffic
between networks.
2. So ware Firewall – A program installed on a computer
or server.
3. Network Firewall – Protects mul ple systems in a
network.
4. Host-based Firewall – Protects a single device.
Func ons of a firewall:
 Packet Filtering – Examines packets and blocks harmful
ones.
 Proxy Service – Acts as a gateway between users and
the internet.
 Stateful Inspec on – Tracks ac ve connec ons and
allows only valid ones.
 Applica on Layer Filtering – Filters data at the
applica on level (e.g., HTTP, FTP).
Benefits:
 Prevents unauthorized access.
 Blocks harmful websites and malware.
 Helps monitor and log network ac vity.
 Supports VPN and remote access securely.
Limita ons:
 Cannot protect against internal threats.
 Cannot stop a acks from trusted users.
 Needs regular updates and configura on.
Firewalls are used in homes, offices, data centers, and cloud
environments. They are a basic and essen al part of any
network security system and are o en used along with
an virus so ware and intrusion detec on systems.

3. PWS (Personal Web Server)


PWS (Personal Web Server) is a lightweight web server
developed by Microso for personal and small-scale use. It
allows users to host and test websites on their own
computers before uploading them to the internet. PWS was
commonly used on Windows 95/98 and NT systems.
With PWS, users can develop web pages using HTML, CSS,
JavaScript, and VBScript, and test how they appear in a
browser. It also supports ASP (Ac ve Server Pages), which
allows dynamic content to be served using server-side scripts.
Features of PWS:
 Hosts simple websites locally.
 Supports scrip ng with VBScript and ASP.
 Allows tes ng of web forms and basic server-side logic.
 Provides a browser-based management interface.
Purpose:
 Ideal for beginners learning web development.
 Allows tes ng without buying hos ng services.
 Useful for developing and debugging websites offline.
Advantages:
 Easy to install and use.
 No internet required to run and test websites.
 Fast tes ng on local machine.
Limita ons:
 Outdated and not supported in modern Windows
versions.
 Limited to basic features; not suitable for large or
complex websites.
 Lacks modern security features.
Today, PWS has been replaced by more advanced tools like IIS
(Internet Informa on Services) and development
environments like XAMPP, WAMP, or Visual Studio Code.
However, PWS played an important role in the early days of
web development, especially for students and hobbyists
learning how websites work.

4. IIS (Internet Informa on Services)


IIS (Internet Informa on Services) is a web server so ware
developed by Microso . It is used to host websites and web
applica ons on Windows systems. IIS supports mul ple
protocols such as HTTP, HTTPS, FTP, SMTP, and more.
IIS is built into Windows opera ng systems (like Windows
Server and Professional edi ons), and it provides a graphical
user interface (GUI) for easy management of websites,
domains, security, and server se ngs.
Key features of IIS:
 Supports ASP.NET, PHP, HTML, and other web
technologies.
 Can host mul ple websites on a single server.
 Provides strong security op ons, such as SSL/TLS,
authen ca on, and firewalls.
 Offers detailed logging and error tracking for
monitoring.
 Supports remote administra on and load balancing.
How IIS Works:
1. A client sends a request (e.g., opening a website).
2. IIS receives and processes the request.
3. It fetches the required files or executes the applica on.
4. The server sends back the response to the client’s
browser.
Advantages:
 Deep integra on with Windows and Microso tools.
 Easy to configure with a user-friendly interface.
 Reliable and secure for enterprise use.
Limita ons:
 Works only on Windows opera ng systems.
 May require licensing for full features in enterprise use.
 Not as flexible with open-source technologies compared
to Apache.
IIS is widely used by companies, government websites, and
developers working with Microso technologies like ASP.NET.
It is a professional and powerful web server for hos ng and
managing modern web applica ons.

5. Apache Web Server


Apache Web Server is one of the most popular and widely
used open-source web servers. It is developed and
maintained by the Apache So ware Founda on. Apache is
available for various opera ng systems like Windows, Linux,
and macOS.
Apache is used to host websites and web applica ons by
processing requests and delivering web pages to users. It
supports both sta c content (like HTML, images) and
dynamic content (like PHP, Python).
Key Features:
 Supports various programming languages like PHP, Perl,
and Python.
 Allows modular configura on through .conf files.
 Enables features like URL rewri ng, compression, and
virtual hos ng.
 Secure and frequently updated by the open-source
community.
How Apache Works:
1. A user types a website address in a browser.
2. The browser sends a request to the server.
3. Apache receives the request and finds the matching file.
4. Apache sends the response (web page) back to the user.
Installa on and Use:
 On Windows, Apache can be installed using XAMPP or
WAMP.
 On Linux, it can be installed using commands like sudo
apt install apache2.
Advantages:
 Free and open-source.
 Highly customizable using modules.
 Large community support and documenta on.
 Compa ble with most content management systems
(like WordPress).
Limita ons:
 Performance can slow under very high traffic without
op miza on.
 Requires manual configura on for some advanced
features.
Apache is used by developers, students, and companies to
build, test, and deploy websites. Its flexibility, ease of use,
and strong community support make it a trusted choice for
web hos ng around the world.
Compare and Contrast: PWS, IIS, and Apache Web Servers
Web servers are so ware systems that handle web requests
and deliver web pages to users. Among the popular web
server so ware are PWS (Personal Web Server), IIS (Internet
Informa on Services), and Apache HTTP Server. Each of
these has its own features, strengths, and common use cases.
Below is a comparison of these three web servers.

1. Personal Web Server (PWS)


Features:
 Developed by Microso for personal and small-scale
website hos ng.
 Allows developers to test websites locally without
needing internet access.
 Supports sta c content (HTML) and dynamic content
using ASP (Ac ve Server Pages).
 Easy to install and manage on older Windows systems
(like Windows 95/98 and NT).
Advantages:
 Simple and beginner-friendly.
 Good for learning web development and basic tes ng.
 Lightweight with low system resource usage.
Typical Use Cases:
 Ideal for students and hobbyist developers for learning
and tes ng.
 Used in academic labs for personal projects.
 Suitable for offline web development.

2. Internet Informa on Services (IIS)


Features:
 Developed by Microso for professional and enterprise-
level web hos ng.
 Deeply integrated with Windows opera ng systems.
 Supports mul ple protocols like HTTP, HTTPS, FTP, and
SMTP.
 Works well with ASP.NET, .NET Core, and other Microso
technologies.
Advantages:
 Easy to use with a graphical user interface.
 Strong security features, including SSL, authen ca on,
and access control.
 Supports advanced features like load balancing, logging,
and remote management.
Typical Use Cases:
 Used by businesses, government agencies, and
organiza ons using Windows servers.
 Ideal for hos ng ASP.NET and .NET-based applica ons.
 Common in enterprise environments for internal and
external websites.

3. Apache HTTP Server


Features:
 Open-source and cross-pla orm web server developed
by the Apache So ware Founda on.
 Supports many web technologies such as PHP, Perl,
Python, and CGI.
 Highly modular with support for plug-ins and modules
(e.g., mod_rewrite, mod_ssl).
 Configura on done using text files (h pd.conf and
.htaccess).
Advantages:
 Free and widely supported.
 Highly customizable and flexible.
 Large community and regular updates.
 Works with various CMSs like WordPress, Joomla, and
Drupal.
Typical Use Cases:
 Used by developers, hos ng companies, and large
organiza ons.
 Suitable for both small personal websites and large-scale
applica ons.
 Commonly used on Linux servers, but also works on
Windows and macOS.

Performance Comparison
PWS:
 Performance is suitable only for small, personal projects.
 Cannot handle high traffic or complex applica ons.
 Lacks op miza on tools for speed and efficiency.
IIS:
 Op mized for Windows environments.
 Performs well for ASP.NET and enterprise web
applica ons.
 Has built-in performance tuning tools and caching
support.
Apache:
 Offers stable performance for both low and high-traffic
websites.
 Performance can be improved using modules and
caching (e.g., mod_cache).
 On Linux systems, Apache is lightweight and very
efficient.

Scalability Comparison
PWS:
 Not scalable.
 Designed only for small-scale use.
 Cannot be used for mul -user or high-traffic
environments.
IIS:
 Highly scalable.
 Can host mul ple websites with virtual hos ng.
 Supports cloud hos ng, server farms, and enterprise
deployments.
Apache:
 Very scalable.
 Suitable for both shared and dedicated server
environments.
 Easily adapted for cloud-based hos ng and clustered
systems.
Opera ng System Compa bility
PWS:
 Works only on older Windows systems.
 Not supported in modern versions of Windows (post-
Windows 2000).
 Cannot run on Linux or macOS.
IIS:
 Compa ble only with Windows OS (Windows Server and
Professional edi ons).
 Deep integra on with Windows tools like PowerShell
and Ac ve Directory.
 Not available for Linux or macOS.
Apache:
 Cross-pla orm: works on Windows, Linux, and macOS.
 Most commonly used on Linux servers.
 Flexibility makes it ideal for all opera ng system
environments.
Feature PWS IIS Apache

Apache
Developer Microso Microso So ware
Founda on

All levels
Enterprise-level
Target Use Personal tes ng (small to
hos ng
enterprise)

Windows,
Only old
OS Support Windows only Linux,
Windows
macOS

High (on High (esp.


Performance Basic
Windows) on Linux)

Scalability Low High High

Comes with Free and


Free (but
Cost Windows open-
outdated)
(licensed) source

PHP, Perl,
Script Support ASP ASP.NET, PHP Python,
etc.

General
Popular Use ASP.NET apps
Learning/tes ng websites
Case in organiza ons
and blogs
(a) Encryp on Schemes and Their Role in Ensuring
Confiden ality and Integrity in Web Communica on

Encryp on is the method of conver ng readable data (called


plaintext) into a secret code (called ciphertext) so that only
authorized users can read it. The main purpose of encryp on
in web communica on is to protect confiden ality and
integrity of data.
 Confiden ality means only the intended receiver can
read the message.
 Integrity means the message is not changed or
tampered with during transmission.
There are two main types of encryp on schemes:
1. Symmetric Encryp on
o Uses a single key for both encryp on and
decryp on.
o Example: AES (Advanced Encryp on Standard).
o It is fast and suitable for large amounts of data.
2. Asymmetric Encryp on
o Uses a pair of keys: a public key (shared with
everyone) and a private key (kept secret).
o Data encrypted with the public key can only be
decrypted with the private key.
o Example: RSA (Rivest-Shamir-Adleman).
Common Encryp on Protocols Used in Web
Communica on:
1. SSL (Secure Sockets Layer)
o An older protocol used to secure online
connec ons.
o Provides data encryp on, authen ca on, and
message integrity.
2. TLS (Transport Layer Security)
o More secure and modern version of SSL.
o It is used in HTTPS (Hypertext Transfer Protocol
Secure).
o Ensures that data sent between browser and server
is encrypted.
3. HTTPS
o A secure version of HTTP.
o Uses TLS to encrypt communica on between the
web browser and server.
o Used in banking, shopping, and login pages.
4. S/MIME (Secure/Mul purpose Internet Mail
Extensions)
o Encrypts and signs emails to protect against
tampering.
5. PGP (Pre y Good Privacy)
o Also used for securing emails using a combina on
of symmetric and asymmetric encryp on.
6. IPSec (Internet Protocol Security)
o Works at the network layer to secure
communica on between devices.
o Commonly used in VPNs (Virtual Private Networks).
Role in Web Security:
Encryp on protects web data from:
 Hackers trying to steal data during transmission.
 Eavesdropping and man-in-the-middle a acks.
 Unauthorized access to confiden al informa on.
Overall, encryp on is essen al for safe online communica on
and secure transac ons.

(b) Components and Func onali es of Firewalls and


Intrusion Detec on Systems (IDS)

Web servers are o en targeted by hackers and malicious


so ware. To protect them, two important security tools are
used: Firewalls and Intrusion Detec on Systems (IDS). These
tools help in monitoring, filtering, and preven ng
unauthorized access to servers.
1. Firewall
A firewall is a network security system that controls the
incoming and outgoing traffic based on a set of security rules.
Components of a Firewall:
 Packet filter – Checks data packets and allows or blocks
them.
 Proxy server – Acts as a gateway between users and the
internet.
 Stateful inspec on engine – Monitors ac ve
connec ons and remembers the state of the connec on.
 Access control list (ACL) – Set of rules that define what
is allowed or denied.
Func ons of Firewalls:
 Blocks unauthorized access to the network.
 Allows legi mate traffic to pass through.
 Protects against malicious websites and applica ons.
 Filters content based on IP address, port number, or
protocol.
 Logs traffic ac vity for monitoring and analysis.
Types of Firewalls:
 Hardware Firewall – A physical device used in large
networks.
 So ware Firewall – Installed on individual computers or
servers.
 Network Firewall – Protects an en re network.
 Host-based Firewall – Protects a single device or server.

2. Intrusion Detec on System (IDS)


An Intrusion Detec on System monitors network traffic and
alerts administrators when suspicious ac vity is detected.
Components of IDS:
 Sensors – Collect data from network or system.
 Analyzer – Inspects data and detects unusual pa erns.
 Database – Stores known a ack signatures.
 User Interface – Allows admins to view alerts and take
ac on.
Func ons of IDS:
 Detects unauthorized access a empts.
 Iden fies malware or a acks like DDoS, trojans, worms.
 Alerts admin through no fica ons or alarms.
 Can work with firewalls to block threats.
Types of IDS:
 NIDS (Network-based IDS) – Monitors en re network
traffic.
 HIDS (Host-based IDS) – Monitors individual devices or
servers.

Working Together:
 Firewalls act like a security gate, blocking threats.
 IDS acts like a security camera, detec ng suspicious
ac vity inside.
Together, they protect web servers from external a acks and
internal misuse, ensuring safer and more reliable web
services.
(a) Describe the threats and a acks to which the Internet
may be vulnerable.
The internet is a powerful tool, but it is also vulnerable to
many threats and a acks. These can target personal
computers, websites, servers, and en re networks.
Understanding these threats is important for protec ng data
and ensuring safe online communica on.

Common Internet Threats and A acks:


1. Malware (Malicious So ware):
 Includes viruses, worms, Trojans, spyware, and
ransomware.
 Can steal, corrupt, or delete data, and take control of a
system.
 Example: Ransomware locks user files and demands
payment.
2. Phishing:
 A fake message or website tricks users into revealing
personal informa on like passwords or credit card
details.
 O en appears to come from trusted sources like banks
or companies.
3. Denial of Service (DoS) A ack:
 The a acker floods a server or network with too much
traffic.
 The system becomes slow or stops working completely.
 A more advanced version is called Distributed DoS
(DDoS) using many systems to a ack one.
4. Man-in-the-Middle (MITM) A ack:
 The a acker secretly intercepts communica on between
two par es.
 They can read, modify, or steal the data being
transferred.
5. SQL Injec on:
 An a acker enters malicious SQL commands into a web
form.
 It tricks the website into giving access to the database.
 Can be used to steal or delete sensi ve data.
6. Cross-Site Scrip ng (XSS):
 Involves inser ng malicious scripts into webpages.
 These scripts can steal user session data or cookies.
7. Eavesdropping:
 Also called sniffing, where the a acker listens to
unencrypted communica on.
 Can be done on public Wi-Fi to steal login informa on.
8. Spoofing:
 The a acker pretends to be someone else, like a trusted
IP or website.
 Used in phishing and MITM a acks.

Impact of Internet Threats:


 Loss of personal or business data.
 Financial loss or iden ty the .
 Damage to company reputa on.
 Disrup on of services or websites.
To prevent such threats, organiza ons use encryp on,
firewalls, an virus so ware, and intrusion detec on systems.
Users must also stay alert and avoid suspicious links or
downloads.

(b) What is the role of encryp on, digital signature and


firewalls in the context of network security?
Network security is the process of protec ng data, systems,
and communica on across networks from unauthorized
access, a acks, and misuse. Three major tools used in
network security are encryp on, digital signatures, and
firewalls.
1. Encryp on:
Encryp on is the process of conver ng readable data into
unreadable code (ciphertext), so that only authorized users
can read it. It ensures confiden ality and integrity of data.
 Symmetric Encryp on uses the same key for encryp on
and decryp on (e.g., AES).
 Asymmetric Encryp on uses a public and private key
pair (e.g., RSA).
Role in Network Security:
 Prevents eavesdropping and data the .
 Ensures secure communica on (e.g., HTTPS).
 Used in VPNs, email security, and online banking.

2. Digital Signature:
A digital signature is a cryptographic method that verifies the
authen city and integrity of a digital message or document.
 The sender signs the data using their private key.
 The receiver verifies it using the sender’s public key.
Role in Network Security:
 Confirms the iden ty of the sender (authen ca on).
 Ensures that data is not changed during transmission
(integrity).
 Provides non-repudia on, meaning the sender cannot
deny sending the message.
 Used in secure emails, contracts, and online
transac ons.

3. Firewall:
A firewall acts as a barrier between a trusted internal
network and untrusted external sources like the internet. It
filters traffic based on predefined rules.
Role in Network Security:
 Blocks unauthorized access and harmful traffic.
 Monitors network ac vity and prevents malware a acks.
 Protects against DoS a acks and hacking a empts.
 Used in homes, offices, and data centers.
Types of firewalls include:
 Hardware Firewall – external physical device.
 So ware Firewall – installed on individual computers.
 Network and Host-based Firewalls – protect networks
or individual devices.
(a) Describe the various encryp on schemes that can be
used to secure data.
Encryp on is a process used to protect data by conver ng it
into an unreadable format. Only authorized users who have
the correct key can decrypt the data and read it. Encryp on
ensures that sensi ve informa on like passwords, credit card
details, or personal messages remain private and secure,
especially during transmission over the internet.
There are two main types of encryp on schemes: Symmetric
Encryp on and Asymmetric Encryp on.

1. Symmetric Encryp on:


 In symmetric encryp on, the same key is used for both
encryp on and decryp on.
 It is fast and suitable for encryp ng large amounts of
data.
 However, the main challenge is key distribu on — both
sender and receiver must have the same secret key.
Examples:
 AES (Advanced Encryp on Standard): Most widely used
symmetric algorithm. Secure and fast.
 DES (Data Encryp on Standard): An older algorithm,
now considered less secure.
 Blowfish and RC4: Other symmetric encryp on methods
used in so ware and network applica ons.
Use cases:
 Encryp ng files, databases, and VPNs.
 Disk encryp on so ware like BitLocker.

2. Asymmetric Encryp on:


 This method uses a pair of keys — a public key for
encryp on and a private key for decryp on.
 It solves the problem of key sharing in symmetric
encryp on.
 Asymmetric encryp on is slower, but more secure for
transmi ng data over public networks.
Examples:
 RSA (Rivest–Shamir–Adleman): Most popular
asymmetric algorithm, used in digital signatures and
HTTPS.
 ECC (Ellip c Curve Cryptography): A modern and more
efficient method, requiring smaller key sizes.
Use cases:
 Secure email communica on (e.g., PGP).
 Online banking, digital signatures, and SSL/TLS
cer ficates.
3. Hybrid Encryp on:
 Combines symmetric and asymmetric methods.
 Asymmetric encryp on is used to exchange the
symmetric key, which then encrypts the data.
 Provides both security and speed.
Example:
 Used in HTTPS (web encryp on), where SSL/TLS uses
both RSA and AES.

Encryp on plays a major role in confiden ality, integrity, and


authen ca on. It protects data from hackers, ensures secure
communica on, and builds trust in digital systems.

(b) What is the purpose of Digital Signatures and Firewalls in


Internet security?
Digital signatures and firewalls are two important tools in
internet security. Both help protect data and systems from
unauthorized access, manipula on, and cyber-a acks.

Digital Signatures:
A digital signature is a mathema cal technique used to verify
the authen city and integrity of a message, document, or
so ware.
How it works:
 A sender uses their private key to digitally sign a
message.
 The receiver uses the sender’s public key to verify the
signature.
 If the verifica on is successful, it proves that the
message has not been altered and is really from the
claimed sender.
Purpose in Internet Security:
 Authen ca on: Confirms the iden ty of the sender.
 Integrity: Ensures that the data has not been changed
during transmission.
 Non-repudia on: The sender cannot deny sending the
message later, as the signature is unique.
Use Cases:
 Secure email communica on.
 Signing so ware or documents.
 Digital contracts and cer ficates.

Firewalls:
A firewall is a security system that monitors and controls
incoming and outgoing network traffic. It acts as a barrier
between a trusted internal network and untrusted external
sources like the internet.
Types of Firewalls:
1. Hardware Firewall: A physical device used to protect
en re networks.
2. So ware Firewall: Installed on individual computers or
servers.
3. Network-Based Firewall: Protects all devices in a
network.
4. Host-Based Firewall: Protects a single system.
Purpose in Internet Security:
 Access Control: Blocks unauthorized access to or from a
private network.
 Threat Detec on: Filters traffic based on rules to
prevent viruses, worms, or hackers.
 Traffic Monitoring: Keeps logs of network ac vity for
future analysis.
Use Cases:
 Corporate networks, servers, cloud pla orms.
 Personal computers to prevent malware and hacking.

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