COMPUTER NETWORKS (PART-2)�(CBSE CLASS XII)

BY: GAUTAM SETH�PGT-IT�JNV TRIVANDRUM

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NETWORK SECURITY CONCEPTS

• Network security deals with policies adopted by network administrator to protect the network from unauthorized access and misuse of network resources. It also ensures that the authorized users have adequate access to all the network resources.

Virus

• A virus is a self-replicating malicious piece of code that attaches itself to other host programs and gain control over the system without the owner's knowledge.

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Worm

• A worm is a self-replicating piece of code that uses security holes in a computer networks to copy itself to the new machine. It does not need to attach itself to a host program
• They could consume the entire memory or bandwidth and clog the network traffic.

Trojan

• A Trojan horse is a non-self replicating a program that contains hidden malicious functions.
• It tricks users into installing them disguised as useful program.

Spam

• Repetition of worthless text in the form of messages or mails is known as Spam. Most spam is commercial advertising.

Cookies

• a small text file send to the web browser by the web server known as a cookie. Generally a cookie contains the name of the website from which it has come and a unique ID tag.
• Some cookies are stored on disk and last until they expires or manually deleted while other last until the browser is closed are not stored on your hard drive.

• They are usually used to track the pages you visit so that information can be customized for you.

Firewall

• A firewall is hardware or software based network security system. It prevents unauthorized access to or from a network.
• All inbound data entering the network or outbound traffic leaving the network pass through the firewall.

Https: Hyper Text Transfer Protocol Secure (HTTPS)

• is the secure version of HTTP.
• The 'S' at the end of HTTPS stands for 'Secure'. It means all communications between your browser and the website are encrypted.

INDIA IT ACT

• The Information Technology Act, 2000 (also known as ITA-2000, or the IT Act) is an Act of the Indian Parliament (No 21 of 2000) notified on 17 October 2000.
• It is the primary law in India dealing with cybercrime and electronic commerce.
• The laws apply to the whole of India. Persons of other nationalities can also be indicted under the law, if the crime involves a computer or network located in India.
• The Act provides legal framework for electronic governance by giving recognition to electronic records and digital signatures.

• The above Act was further amended in the form of IT Amendment Act, 2008 [ITAA-2008]
• Some of the offenses are as follows

- Tampering with computer source documents

- Hacking with computer system

- Acts of cyber terrorism

- Publishing information which is obscene in electronic form.

Cyber Law

• Cyber law or Internet law is a term that encapsulates the legal issues related to use of the Internet.
• its domain covers many areas of law and regulation, such as internet access and usage, privacy, freedom of expression, and jurisdiction.

Cyber Crime

• Any unlawful act wherein the computer is either a tool or a target or both.
• Cyber-crimes can involve criminal activities that are traditional in nature, such as theft, fraud, forgery, defamation and mischief, all of which are subject to the Indian Penal Code.

INTELLECTUAL PROPERTY RIGHTS (IPR) ISSUES

• Intellectual property rights are the rights given to an individual over the invention of their own.
• They usually give the creator an exclusive right over the use of his/her creation for a certain period of time.

Ways to protect intellectual property

• Patents: A Patent is a term used for a specific product designed by an individual.
• Trademarks: Trademark can be defined as a name or a different sign or a device identifying a product or a service provided by a person or a company.
• A Trademark is also known as brand name

- Copyrights: Copyright is the term used for a written document. A legal action can be taken, if copyrights are violated.

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Hacking

• Hacking is unauthorized intrusion into a computer or a network.
• The person engaged in hacking activities is generally referred to as a hacker.
• This hacker may alter system or security features to accomplish a goal that differs from the original purpose

A hacker (white hat)

• accesses the computer without the intention of destroying data or maliciously harming the computer. White hat is known as ethical hacker

A cracker (black hat)

• gain unauthorized access to a computer with the intention to cause damage. Black hat is a hacker who violates computer security for maliciousness or for personal gain

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INTRODUCTION TO WEB SERVICES

WWW (World Wide Web)

• WWW is a network of web servers. It can be defined as a hypertext information retrieval system on the Internet. All the web pages on WWW use HTTP for making hypertext jumps.

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HTML (Hypertext Markup Language)

- HTML is a markup language to create and design web content.

- It is used to display the data in formatted manner.

• It has a variety of predefined tags and attributes for defining the layout and structure of the web document.
• HTML is not case sensitive

- A HTML document has the extension .htm or .html

- HTML documents have a head and body.

<html>

<head>………………

</head>

<body>………………

</body>

</html>

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XML (eXtensible Markup Language)

• XML is a markup language that is self- descriptive.
• It is used to carry, store or exchange data.
• It does not have predefined tags. It is possible to define new tags in XML.
• It allows the programmer to use customized tags.
• XML is case sensitive.
• A HTML document has the extension .xml

• XML documents form a tree structure.

<root>

<child>

<subchild>.....

</subchild>

</child>

</root>

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HTTP (HYPERTEXT TRANSFER PROTOCOL )

• It is the protocol that is used for transferring hypertext (text, graphic, image, sound, video etc.) between two computers and is particularly used on the World Wide Web.
• It is a TCP/IP based communication protocol and provides a standard for Web browsers and servers to communicate.
• HTTP is based on Client/Server principle.
• Communication between the host and the client occurs through a request/response pair.

DOMAIN NAMES

• Every computer on the network has a unique numeric address assigned to it, called as IP address. For Ex. 59.177.134.72
• Since it is impossible for a person to remember the IP addresses.
• A system has been developed which assigns domain names to web servers and maintains a database of these names and corresponding IP addresses on DNS (Domain Name Service) server.
• Examples of some domain names are cbse.nic.in, indianrailway.gov.in etc.

• A domain name usually has more than one part for example, in the domain name www.cbse.nic.in
• in is the primary domain name
• nic is the sub-domain of in
• cbse is the sub-domain of nic
• www indicates the server is on world wide web

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• Top level domains are further divided into two categories:

Generic Domain Names:

·com - commercial business

·edu - Educational institutions

·gov - Government agencies

·mil - Military

·net - Network organizations

·org - Organizations (non-profit)

Country Specific Domain Names

.in - India

·au - Australia

·ca - Canada

.ch - China

.nz - New Zealand

.pk - Pakistan

.jp - Japan

.us - United States of America

URL (UNIFORM RESOURCE LOCATOR)

• A URL is a formatted text string used to identify a network resource on the Internet.
• Network resources can be plain Web pages, text documents, graphics, downloadable files, services or programs.
• Every network resource on the web has a unique URL in the following format:

Protocol: // domain name /path / file name

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• The URL text string consists of three parts:
• Network Protocol: The network protocol identifies the protocol to be used to access the network resource. Some examples of protocols include http, ftp and mailto.
• Domain name: It identifies the host/server that holds the resource. For example: www. school.com is a domain name.
• Resource Location: It consists of the path or directory and the file name of resource.

• For example in the URL : http://www.school.com/syllabus/preprimary/nursery.htm��the file nursery.htm is stored in the sub directory preprimary, of the directory syllabus on the server www.school.com
• Website: Related webpages from a single web domain is termed as a website. A website has multiple webpages providing information about a particular entity.

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• Web browser: Web browser is software program to navigate the web pages on the internet.
• A bowser interprets the coding language of the web page and displays it in graphic form.
• In client–server model of Internet a web browser is a client which requests the information from the web server.
• The web server sends the information back to the client.
• Some of the web browsers are: Netscape Navigator, Internet Explorer, Mozilla Firefox etc.

• Web Server: A Web server is a computer or a group of computers that stores web pages on the internet.
• It works on client/server model. It delivers the requested web page to web browser.
• Web servers use special programs such as Apache or IIS to deliver web pages over the http protocol.
• Web hosting: Web hosting is the process of uploading/saving the web content on a web server to make it available on WWW.
• In case an individual or a company wants to make its website available on the internet, it should be hosted on a web server.

• Web page: Web page is an electronic document designed using HTML.
• It displays information in textual or graphical form. It may also contain downloadable data files, audio files or video files.
• Traversal from one webpage to another web page is possible through hyperlinks.
• A web page can be classified into two types:
• Static web page: A web page which displays same kind of information whenever a user visits.
• Dynamic web page: An interactive web page is a dynamic webpage. A dynamic web page uses scripting languages to display changing content on the web page.

• Scripting language: It is a programming language which can be embedded or integrated with other languages.
• Some of the most widely used scripting languages are JavaScript, VBScript, PHP, Perl, Python, Ruby, and ASP.
• Dynamic web pages support two types of scripting:
• Client-Side Scripting: On some web pages the contents change in response to an action done by the user, for example a click from the mouse or a key press from a keyboard action.
• The content is generated on the user's local computer. VB Script and Java Script are examples of client-side scripting languages

• Server-Side Scripting: Some web pages use applications running on the server to generate the web content. Such pages use server-side scripting language.
• Web page display the current time and date, forums, submission of forms, shopping carts etc. uses server-side scripting. ASP, JSP, PHP are examples of server-side scripting languages.

• Web 2.0: Web 2.0 refers to new generation of dynamic and interactive websites. Web 2.0 websites uses a new programming language called AJAX (Asynchronous JavaScript and XML).
• AJAX helps a dynamic website connect to the web server and download small amount of data based on the interaction with the user.
• In this technology only the part of the website which is updated is reloaded. The entire page does not get reloaded each time. This helps in making the website interactive.

• Applications supported by web 2.0 are as followings:
• blogging
• social networking
• RSS (Really Simple Syndication)
• wikis and other collaborative applications
• interactive encyclopedias and dictionaries
• Advanced Gaming

• E-commerce payment transactions: E-Commerce or Electronics Commerce sites use electronic payment that is paperless monetary transactions.
• Electronic payment has revolutionized the business processing by reducing paper work, transaction costs, labour cost.
• Being user friendly and less time consuming than manual processing it helps business organization to expand its market.

• Online Banking: Online banking, also known as internet banking, e-banking or virtual banking, is an electronic payment system that enables customers of a bank or other financial institution to conduct a range of financial transactions through the financial institution's website.
• Mobile Banking: Mobile banking refers to the use of a smartphone or other cellular device to perform online banking tasks while away from your home computer, such as monitoring account balances, transferring funds between accounts and bill payment.

• Payment Apps and Services:  A mobile payment app lets you send money from your phone, either to other people or to Payment terminal to buy something in a store.
• Some mobile payment apps are BHIM, Google Pay, PayPal, Paytm, Freecharge etc.

THANK YOU