Internet Services

Internet Services

Internet Services allows us to access a huge amount of information such as text, graphics, sound and software over the internet The following four different categories of Internet Services.

• COMMUNICATION SERVICES
• INFORMATION RETRIEVAL SERVICES
• WEB SERVICES
• WORLD WIDE WEB

Communication Services

There are various Communication Services available that offer exchange of information with individuals or groups. The following table gives a brief introduction to these services:

S.N.

Service Description

1

Electronic Mail
Used to send electronic messages over the internet.

2

Telnet -Used to log on to a remote computer that is attached to the internet.

3

Newsgroup
Offers a forum for people to discuss topics of common interests.

4

Internet Relay Chat (IRC)
It allows people from all over the world to communicate in real-time.

5

Mailing Lists
Used to organize a group of internet users to share common information through e-mail.

6

Internet Telephony (VoIP)
It allows internet users to talk across the internet to any PC equipped to receive the call.

7

Instant Messaging
It offers real-time chat between individuals and groups of people. Eg. Yahoo messenger, MSN messenger.

Information Retrieval Services

There exist several Information retrieval services offering easy access to information present on the internet. The following table gives a brief introduction to these services:

S.N.	Service Description
1	File Transfer Protocol (FTP) Enable the users to transfer files.
2	Archie It’s an updated database of public FTP sites and their content. It helps to search a file by its name.
3	Gopher Used to search, retrieve, and display documents on remote sites.
4	Very Easy Rodent Oriented Netwide Index to Computer Achieved (VERONICA) VERONICA is a gopher based resource. It allows access to the information resource stored on gopher’s servers.

Web Services
World Wide Web (WWW)
Video Conferencing
Modes of Video Conferencing
POINT-TO-POINT
MULTI-POINT
The TCP/IP Reference Model
Overview of TCP/IP reference model

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Different Layers of TCP/IP Reference Model
Layer 1: Host-to-network Layer

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Layer 2: Internet layer

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Layer 3: Transport Layer

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Layer 4: Application Layer

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Merits of TCP/IP model

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Demerits of TCP/IP
Web Client
Web Server Working
Architecture
Concurrent Approach
Multi-processing
Multi-threaded
Hybrid
Examples

S.N.	Web Server Description
1	Apache HTTP Server This is the most popular web server in the world developed by the Apache Software Foundation. Apache web server is an open source software and can be installed on almost all operating systems including Linux, UNIX, Windows, FreeBSD, Mac OS X and more. About 60% of the web server machines run the Apache Web Server.
2.	Internet Information Services (IIS) The Internet Information Server (IIS) is a high performance Web Server from Microsoft. This web server runs on Windows NT/2000 and 2003 platforms (and may be on upcoming new Windows version also). IIS comes bundled with Windows NT/2000 and 2003; Because IIS is tightly integrated with the operating system so it is relatively easy to administer it.
3.	Lighttpd The lighttpd, pronounced lighty is also a free web server that is distributed with the FreeBSD operating system. This open source web server is fast, secure and consumes much less CPU power. Lighttpd can also run on Windows, Mac OS X, Linux and Solaris operating systems.
4.	Sun Java System Web Server This web server from Sun Microsystems is suited for medium and large web sites. Though the server is free it is not open source. It, however, runs on Windows, Linux, and UNIX platforms. The Sun Java System web server supports various languages, scripts, and technologies required for Web 2.0 such as JSP, Java Servlets, PHP, Perl, Python, and Ruby on Rails, ASP and Coldfusion, etc.
5.	Jigsaw Server Jigsaw (W3C's Server) comes from the World Wide Web Consortium. It is open-source and free and can run on various platforms like Linux, UNIX, Windows, and Mac OS X Free BSD, etc. Jigsaw has been written in Java and can run CGI scripts and PHP programs.

Internet Security 
Internet security is generally becoming a top priority for both businesses and governments. Good Internet security protects financial details and much more of what is handled by a business or agency’s servers and network hardware. Insufficient Internet security can threaten to collapse an e-commerce business or any other operation where data gets routed over the Web.

1. ·        Malware, short for malicious software, is any software used to disrupt computer operation, gather sensitive information, or gain access to private computer systems. Malware is defined by its malicious intent, acting against the requirements of the computer user, and does not include software that causes unintentional harm due to some deficiency. The term badware is sometimes used and applied to both true (malicious) malware and unintentionally harmful software.

1. ·        A botnet is a network of zombie computers that have been taken over by a robot or bot that performs large-scale malicious acts for the creator of the botnet.

1. ·        Computer Viruses are programs that can replicate their structures or effects by infecting other files or structures on a computer. The common use of a virus is to take over a computer to steal data.

1. ·        Computer worms are programs that can replicate themselves throughout a computer network, performing malicious tasks throughout.

1. ·        Ransomware is a type of malware which restricts access to the computer system that it infects, and demands a ransom paid to the creator(s) of the malware in order for the restriction to be removed.

1. ·        Scareware is scam software of usually limited or no benefit, containing malicious payloads, that is sold to consumers via certain unethical marketing practices. The selling approach uses social engineering to cause shock, anxiety, or the perception of a threat, generally directed at an unsuspecting user.

1. ·        Spyware refers to programs that surreptitiously monitor activity on a computer system and report that information to others without the user's consent.

1. ·        A Trojan horse, commonly known as a Trojan, is a general term for malicious software that pretends to be harmless, so that a user willingly allows it to be downloaded onto the computer.

1. ·        KeyLogger, Keystroke logging, often referred to as keylogging or keyboard capturing is the action of recording (logging) the keys struck on a keyboard.

Denial-of-service attacks
Phishing

1.	Content Gateway receives a user request for a Web object.
2.	Using the Web address, the proxy tries to locate the requested object in its object store (cache).

3.	If the object is in the cache, the proxy checks to see if the object is fresh enough to serve If the object is fresh, the proxy serves it to the user as a cache hit.
4.	If the data in the cache is stale, the proxy connects to the origin server and asks if the object is still fresh (a revalidation). If the object is still fresh, the proxy sends the cached copy to the user immediately.

5.

If the object is not in the cache (a cache miss) or the server indicates that the cached copy is no longer valid, the proxy obtains the object from the origin server, simultaneously streaming it to the user and the cache. Subsequent requests for the object will be served faster because the object will come directly from the cache.

A client initially connects with a proxy server to send a request, such as accessing a file or opening a Web page. The proxy server filters and evaluates each IP address and request. The verified request is forwarded to the relevant server, which requests the service on behalf of the client.
A proxy server is used for many purposes, including:

• To provide internal system security

• To speed up resource access

• To apply access policies for tracking organizational Internet use or assessing employee progress.

• To bypass special controls, such as parental or security controls

• To scan for viruses and malware

• To circumvent regional restrictions

• To allow websites to make requests to externally hosted resources when cross-domain restrictions prohibit websites from linking to outside domains

Cyber Law of India: Introduction

The Computer as a Target: -using a computer to attack other computers.
Cyber Crime regulated by Cyber Laws or Internet Laws.
Technological advancements have created new possibilities for criminal activity, in particular, the criminal misuse of information technologies such as
Cyber Stacking:-
Identity theft is the fastest growing crime in countries like America.
HTTP Non-Persistent & Persistent Connection
2. One RTT is used for HTTP request and first few bytes to HTTP response to return.

Difference between Persistent & Non-Persistent connection.

Each objection takes two RTT (assuming no window limit) one for TCP connection and other for HTTP image/text file.
1) Lower CPU and memory usage because there are fewer connections.
2) Allows HTTP pipelining of requests and responses.
3) Reduced network congestion (fewer TCP connections).
4) Reduced latency in subsequent requests (no handshaking).
5) Errors can be reported without the penalty of closing the TCP connection.
Resources may be kept occupied even when not needed and may not be available to others.

Web services allow the exchange of information between applications on the web. Using web services, applications can easily interact with each other.

The web services are offered using the concept of Utility Computing.

WWW is also known as W3. It offers a way to access documents spread over several servers over the internet. These documents may contain texts, graphics, audio, video, hyperlinks. The hyperlinks allow the users to navigate between the documents.

Video conferencing or Video teleconferencing is a method of communicating by two-way video and audio transmission with the help of telecommunication technologies.

This mode of conferencing connects two locations only.

This mode of conferencing connects more than two locations through Multi-point Control Unit (MCU).

TCP/IP means Transmission Control Protocol and Internet Protocol. It is the network model used in the current Internet architecture as well. Protocols are a set of rules which govern every possible communication over a network. These protocols describe the movement of data between the source and destination or the internet. They also offer simple naming and addressing schemes.

TCP/IP that is Transmission Control Protocol and Internet Protocol was developed by Department of Defence's Project Research Agency (ARPA, later DARPA) as a part of a research project of network interconnection to connect remote machines.

The features that stood out during the research, which led to making the TCP/IP reference model were:

·        Support for a flexible architecture. Adding more machines to a network was easy.

·        The network was robust, and connections remained intact until the source and destination machines were functioning.

The overall idea was to allow one application on one computer to talk to(send data packets) another an application running on a different computer.

Below we have discussed the 4 layers that form the TCP/IP reference model:

1.     Lowest layer of the all.

2.     The protocol is used to connect to the host so that the packets can be sent over it.

3.     Varies from host to host and network to network.

1.     The selection of a packet switching network that is based on a connectionless internetwork layer is called an internet layer.

2.     It is the layer that holds the whole architecture together.

3.     It helps the packet to travel independently to the destination.

4.     Order in which packets are received is different from the way they are sent.

5.     IP (Internet Protocol) is used in this layer.

6.     The various functions performed by the Internet Layer are:

o   Delivering IP packets

o   Performing routing

o   Avoiding congestion

1.     It decides if data transmission should be on parallel path or single path.

2.     Functions such as multiplexing, segmenting or splitting on the data is done by transport layer.

3.     The applications can read and write to the transport layer.

4.     The transport layer adds header information to the data.

5.     Transport layer breaks the message (data) into small units so that they are handled more efficiently by the network layer.

6.     The transport layer also arranges the packets to be sent, in sequence.

The TCP/IP specifications described a lot of applications that were at the top of the protocol stack. Some of them were TELNET, FTP, SMTP, DNS etc.

1.     TELNET is a two-way communication protocol which allows connecting to a remote machine and run applications on it.

2.     FTP(File Transfer Protocol) is a protocol, that allows File transfer amongst computer users connected over a network. It is reliable, simple and efficient.

3.     SMTP(Simple Mail Transport Protocol) is a protocol, which is used to transport electronic mail between a source and destination, directed via a route.

4.     DNS(Domain Name Server) resolves an IP address into a textual address for Hosts connected over a network.

5.     It allows peer entities to carry conversation.

6.     It defines two end-to-end protocols: TCP and UDP

o   TCP(Transmission Control Protocol): It is a reliable connection-oriented protocol that handles byte-stream from source to destination without error and flow control.

o   UDP(User-Datagram Protocol): It is an unreliable connectionless protocol that do not want TCPs, sequencing and flow control. Eg: One-shot request-reply kind of service.

1.     It operated independently.

2.     It is scalable.

3.     Client/server architecture.

4.     Supports a number of routing protocols.

5.     Can be used to establish a connection between two computers.

1.     In this, the transport layer does not guarantee the delivery of packets.

2.     The model cannot be used in any other application.

3.     Replacing protocol is not easy.

4.     It has not clearly separated its services, interfaces, and protocols.

Transmission Control Protocol

Transmission control protocol (TCP) is a network communication protocol designed to send data packets over the Internet.

TCP is a transport layer protocol in the OSI layer and is used to create a connection between remote computers by transporting and ensuring the delivery of messages over supporting networks and the Internet.

Transmission Control Protocol is one of the most used protocols in digital network communications and is part of the Internet protocol suite, commonly known as the TCP/IP suite. Primarily, TCP ensures end-to-end delivery of data between distinct nodes. TCP works in collaboration with Internet Protocol, which defines the logical location of the remote node, whereas TCP transports and ensures that the data is delivered to the correct destination.

Before transmitting data, TCP creates a connection between the source and destination node and keeps it live until the communication is active. TCP breaks large data into smaller packets and also ensures that the data integrity is intact once it is reassembled at the destination node.

In Other Words:-

The Transmission Control Protocol (TCP) is a connection-oriented reliable protocol. It provides a reliable transport service between pairs of processes executing on End Systems (ES) using the network layer service provided by the IP protocol.

TCP providing reliable data transfer to FTP over an IP network using Ethernet

TCP is stream-oriented, that is, TCP protocol entities exchange streams of data. Individual bytes of data (e.g. from an application or session layer protocol) are placed in memory buffers and transmitted by TCP in transport Protocol Data Units (for TCP these are usually known as "segments"). The reliable, flow-controlled TCP service is much more complex than UDP, which only provides a Best Effort service. To implement the service, TCP uses a number of protocol timers that ensure reliable and synchronized communication between the two End Systems.

For most networks approximately 90% of current traffic uses this transport service. It is used by such applications as telnet, World Wide Web (WWW), ftp, electronic mail. The transport header contains a Service Access Point which indicates the protocol which is being used (e.g. 23 = Telnet; 25 = Mail; 69 = TFTP; 80 = WWW (http)). The port numbers associated with these services generally have the same value as those used for UDP services  (a full list of all port numbers is provided in the reference at the end of this page).

A web client is an application that communicates with a web server, using the Hypertext Transfer Protocol (HTTP). Hypertext Transfer Protocol is the protocol behind the World Wide Web. With every web transaction, HTTP is invoked.

Web Server

A Web server is a program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their requests, which are forwarded by their computers' HTTP clients. Dedicated computers and appliances maybe referred to as Web servers as well.

Web server is a computer where the web content is stored. Basically, a web server is used to host the web sites but there exist other web servers also such as gaming, storage, FTP, email, etc.

Web site is a collection of web pages while the webserver is a software that respond to the request for web resources.

Web server responds to the client request in either of the following two ways:

·      Sending the file to the client associated with the requested URL.

·      Generating response by invoking a script and communicating with database

Key Points

·      When client sends a request for a web page, the webserver search for the requested page if the requested page is found then it will send it to the client with an HTTP response.

·      If the requested web page is not found, web server will send an HTTP response:Error 404 Not found.

·      If the client has requested for some other resources then the web server will contact to the application server and data store to construct the HTTP response.

Web Server Architecture follows the following two approaches:

1.    Concurrent Approach

2.    Single-Process-Event-Driven Approach.

Concurrent approach allows the web server to handle multiple client requests at the same time. It can be achieved by the following methods:

·      Multi-process

·      Multi-threaded

·      Hybrid method.

In this, a single process (parent process) initiates several single-threaded child processes and distributes incoming requests to these child processes. Each of the child processes are responsible for handling a single request.

It is the responsibility of the parent process to monitor the load and decide if processes should be killed or forked.

Unlike Multi-process, it creates multiple single-threaded processes.

It is a combination of the above two approaches. In this approach, multiple processes is created and each process initiates multiple threads. Each of the threads handles one connection. Using multiple threads in a single process results in less load on system resources.

Following table describes the most leading web servers available today:

Internet security is a catch-all term for a very broad issue covering security for transactions made over the Internet. Generally, Internet security encompasses browser security, the security of data entered through a Web form, and overall authentication and protection of data sent via Internet Protocol.

Internet security relies on specific resources and standards for protecting data that gets sent through the Internet. This includes various kinds of encryption such as Pretty Good Privacy (PGP). Other aspects of a secure Web setup includes firewalls, which block unwanted traffic, and anti-malware, anti-spyware and anti-virus programs that work from specific networks or devices to monitor Internet traffic for dangerous attachments.

Threats

an internet user can be tricked or forced into downloading software onto a computer that is of malicious intent. Such software comes in many forms, such as viruses, Trojan horses, spyware, and worms.

A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. Another way of understanding DDoS is seeing it as attacks in cloud computing environment that are growing due to the essential characteristics of cloud computing.^] Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely. According to businesses who participated in an international business security survey, 25% of respondents experienced a DoS attack in 2007 and 16.8% experienced one in 2010.

Phishing is an attack that targets online users for the extraction of their sensitive information such as username, password and credit card information. Phishing occurs when the attacker pretends to be a trustworthy entity, either via email or web page. Victims are directed to fake web pages, which are dressed to look legitimate, via spoof emails, instant messenger/social media or other avenues. Often tactics such as email spoofing are used to make emails appear to be from legitimate senders, or long complex subdomains hide the real website host. Insurance group RSA said that phishing accounted for worldwide losses of $1.5 billion in 2012.

Web Proxy Caching

Web proxy caching stores copies of frequently accessed Web objects (such as documents, images, and articles) close to users and serves this information to them. Internet users get their information faster, and Internet bandwidth is freed for other tasks.

Internet users direct their requests to Web servers all over the Internet. For a caching server to serve these requests, it must act as a Web proxy server. A Web proxy server receives user requests for Web objects and either serves the requests or forwards them to the origin server (the Web server that contains the original copy of the requested information).

Content Gateway supports both transparent proxy deployment, in which the user's client software (typically a browser) is unaware that it is communicating with a proxy, and explicit proxy deployment, in which the user's client software is configured to send requests directly to the proxy.

Cache requests

The following overview illustrates how Content Gateway serves a user request.

Proxy Server

A proxy server verifies and forwards incoming client requests to other servers for further communication. A proxy server is located between a client and a server where it acts as an intermediary between the two, such as a Web browser and a Web server. The proxy server's most important role in providing security.

Network intelligence has advanced with the development of enhanced tools and network services such as the proxy server.

Simple way, we can say that cybercrime is unlawful acts wherein the computer is either a tool or a target or both

Cybercrimes 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. The abuse of computers has also given birth to a gamut of new age crimes that are addressed by the Information Technology Act, 2000.

We can categorize Cyber crimes in two ways

e.g. Hacking, Virus/Worm attacks, DOS attack, etc.

The computer as a weapon: -using a computer to commit real-world crimes.

e.g. Cyber Terrorism, IPR violations, Credit card frauds, EFT frauds, Pornography, etc.

Technical Aspects

a. Unauthorized access & Hacking:-

Access means gaining entry into, instructing or communicating with the logical, arithmetical, or memory function resources of a computer, computer system or computer network.

Unauthorized access would, therefore, mean any kind of access without the permission of either the rightful owner or the person in charge of a computer, computer system or computer network.

Every act committed to breaking into a computer and/or network is hacking. Hackers write or use ready-made computer programs to attack the target computer. They possess the desire to destruct and they get the kick out of such destruction. Some hackers hack for personal monetary gains, such as to stealing the credit card information, transferring money from various bank accounts to their own account followed by withdrawal of money.

By hacking web server taking control of another person's website called as web hijacking

b. Trojan Attack:-

The program that acts like something useful but do the things that are quiet damping. The programs of this kind are called Trojans.

The name Trojan Horse is popular.

Trojans come in two parts, a Client part, and a Server part. When the victim (unknowingly) runs the server on its machine, the attacker will then use the Client to connect to the server and start using the trojan.

TCP/IP protocol is the usual protocol type used for communications, but some functions of the trojans use the UDP protocol as well.

c. Virus and Worm attack:-

A program that has the capability to infect other programs and make copies of itself and spread into other programs is called virus.

Programs that multiply like viruses but spread from computer to computer are called as worms.

d. E-mail & IRC related crimes:-

1. Email spoofing

Email spoofing refers to email that appears to have been originated from one source when it was actually sent from another source. Please Read 

2. Email Spamming

Email "spamming" refers to sending emails to thousands and thousands of users - similar to a chain letter.

3 Sending malicious codes through email

E-mails are used to send viruses, Trojans, etc through emails as an attachment or by sending a link of website which on visiting downloads malicious code.

4. Email bombing

E-mail "bombing" is characterized by abusers repeatedly sending an identical email message to a particular address.

5. Sending threatening emails

6. Defamatory emails

7. Email frauds

8. IRC related

Three main ways to attack IRC are: "verbalâ⦣8218;?Ŧ#8220; attacks, clone attacks, and flood attacks.

e. Denial of Service attacks:-

Flooding a computer resource with more requests than it can handle. This causes the resource to crash thereby denying access of service to authorized users.

Examples include

attempts to "flood" a network, thereby preventing legitimate network traffic

attempts to disrupt connections between two machines, thereby preventing access to a service

attempts to prevent a particular individual from accessing a service

attempts to disrupt service to a specific system or person. 

Distributed DOS

A distributed denial of service (DoS) attack is accomplished by using the Internet to break into computers and using them to attack a network.

Hundreds or thousands of computer systems across the Internet can be turned into “zombies” and used to attack another system or website.

Types of DOS

There are three basic types of attack:

a. Consumption of scarce, limited, or non-renewable resources like NW bandwidth, RAM, CPU time. Even power, cool air, or water can affect.

b. Destruction or Alteration of Configuration Information

c. Physical Destruction or Alteration of Network Components

e. Pornography:-

The literal mining of the term 'Pornography' is “describing or showing sexual acts in order to cause sexual excitement through books, films, etc.”

This would include pornographic websites; pornographic material produced using computers and use of internet to download and transmit pornographic videos, pictures, photos, writings etc.

Adult entertainment is the largest industry on the internet.There are more than 420 million individual pornographic webpages today.

Research shows that 50% of the web-sites containing potentially illegal contents relating to child abuse were ‘Pay-Per-View’. This indicates that abusive images of children over the Internet have been highly commercialized.

Pornography delivered over mobile phones is now a burgeoning business, “driven by the increase in sophisticated services that deliver video clips and streaming video, in addition to text and images.”

Effects of Pornography

Research has shown that pornography and its messages are involved in shaping attitudes and encouraging behavior that can harm individual users and their families.

Pornography is often viewed in secret, which creates deception within marriages that can lead to divorce in some cases.

In addition, pornography promotes the allure of adultery, prostitution and unreal expectations that can result in dangerous promiscuous behavior.

Some of the common, but false messages sent by sexualized culture.

Sex with anyone, under any circumstances, any way it is desired, is beneficial and does not have negative consequences.

Women have one value - to meet the sexual demands of men.

Marriage and children are obstacles to sexual fulfillment.

Everyone is involved in promiscuous sexual activity, infidelity, and premarital sex.

Pornography Addiction

Dr. Victor Cline, an expert on Sexual Addiction, found that there is a four-step progression among many who consume pornography.

1.Addiction: Pornography provides a powerful sexual stimulant or aphrodisiac effect, followed by sexual release, most often through

masturbation.

2.Escalation: Over time addicts require more explicit and deviant material to meet their sexual "needs."

3.Desensitization: What was first perceived as gross, shocking and disturbing, in time becomes common and acceptable.

4.Acting out sexually: There is an increasing tendency to act out behaviors viewed in pornography.

g. Forgery:-

Counterfeit currency notes, postage and revenue stamps, mark sheets, etc can be forged using sophisticated computers, printers, and scanners.

Also impersonate another person is considered forgery.

h. IPR Violations:-

These include software piracy, copyright infringement, trademarks violations, theft of computer source code, patent violations. etc.

Cyber Squatting- Domain names are also trademarks and protected by ICANN’s domain dispute resolution policy and also under trademark laws.

Cyber Squatters registers domain name identical to popular service provider’s domain so as to attract their users and get benefit from it.

i. Cyber Terrorism:-

Targeted attacks on military installations, power plants, air traffic control, banks, trail traffic control, telecommunication networks are the most likely targets. Others like police, medical, fire, and rescue systems, etc.

Cyberterrorism is an attractive option for modern terrorists for several reasons.

1.It is cheaper than traditional terrorist methods.

2.Cyberterrorism is more anonymous than traditional terrorist methods.

3.The variety and number of targets are enormous.

4.Cyberterrorism can be conducted remotely, a feature that is especially appealing to terrorists.

5.Cyberterrorism has the potential to affect directly a larger number of people.

j. Banking/Credit card Related crimes:-

In the corporate world, Internet hackers are continually looking for opportunities to compromise a company’s security in order to gain access to confidential banking and financial information.

Use of stolen card information or fake credit/debit cards are common.

Bank employee can grab money using programs to deduce a small amount of money from all customer accounts and adding it to own account also called salami.

k. E-commerce/ Investment Frauds:-

Sales and Investment frauds. An offering that uses false or fraudulent claims to solicit investments or loans or that provides for the purchase, use, or trade of forged or counterfeit securities.

Merchandise or services that were purchased or contracted by individuals online are never delivered.

The fraud attributable to the misrepresentation of a product advertised for sale through an Internet auction site or the non-delivery of products purchased through an Internet auction site.

Investors are enticed to invest in this fraudulent scheme by the promises of abnormally high profits.

l. Sale of illegal articles:-

This would include trade of narcotics, weapons, and wildlife, etc., by posting information on websites, auction websites, and bulletin boards or simply by using email communication.

Research shows that number of people employed in this criminal area. Daily peoples receiving so many emails with offers of banned or illegal products for sale.

m. Online gambling:-

There are millions of websites hosted on servers abroad, that offer online gambling. In fact, it is believed that many of these websites are actually fronts for money laundering.

n. Defamation: -

Defamation can be understood as the intentional infringement of another person's right to his good name.

Cyber Defamation occurs when defamation takes place with the help of computers and / or the Internet. E.g. someone publishes defamatory matter about someone on a website or sends e-mails containing defamatory information to all of that person's friends. Information posted to a bulletin board can be accessed by anyone. This means that anyone can place

Cyber defamation is also called as Cyber smearing.

Cyber stalking involves following a persons movements across the Internet by posting messages (sometimes threatening) on the bulletin boards frequented by the victim, entering the chat-rooms frequented by the victim, constantly bombarding the victim with emails etc.

In general, the harasser intends to cause emotional distress and has no legitimate purpose to his communications.

p. Pedophiles:-

Also there are persons who intentionally prey upon children. Specially with a teen they will let the teen know that fully understand the feelings towards adult and in particular teen parents.

They earns teens trust and gradually seduce them into sexual or indecent acts.

Pedophiles lure the children by distributing pornographic material, then they try to meet them for sex or to take their nude photographs including their engagement in sexual positions.

q. Identity Theft :- 

Identity theft occurs when someone appropriates another's personal information without their knowledge to commit theft or fraud.

Identity theft is a vehicle for perpetrating other types of fraud schemes.

r. Data diddling:-

Data diddling involves changing data prior or during input into a computer.

In other words, information is changed from the way it should be entered by a person typing in the data, a virus that changes data, the programmer of the database or application, or anyone else involved in the process of having information stored in a computer file.

It also include automatic changing the financial information for some time before processing and then restoring original information.

s. Theft of Internet Hours:-

Unauthorized use of Internet hours paid for by another person.

By gaining access to an organisation's telephone switchboard (PBX) individuals or criminal organizations can obtain access to dial-in/dial-out circuits and then make their own calls or sell call time to third parties.

Additional forms of service theft include capturing 'calling card' details and on-selling calls charged to the calling card account, and counterfeiting or illicit reprogramming of stored value telephone cards.

t. Theft of computer system (Hardware):-

This type of offence involves the theft of a computer, some part(s) of a computer or a peripheral attached to the computer.

u. Physically damaging a computer system:-

Physically damaging a computer or its peripheralseither by shock, fire or excess electric supply etc.

v. Breach of Privacy and Confidentiality

Privacy

Privacy refers to the right of an individual/s to determine when, how and to what extent his or her personal data will be shared with others.

Breach of privacy means unauthorized use or distribution or disclosure of personal information like medical records, sexual preferences, financial status etc.

Confidentiality

It means non disclosure of information to unauthorized or unwanted persons.

In addition to Personal information some other type of information which useful for business and leakage of such information to other persons may cause damage to business or person, such information should be protected.

Generally for protecting secrecy of such information, parties while sharing information forms an agreement about he procedure of handling of information and to not to disclose such information to third parties or use it in such a way that it will be disclosed to third parties.

Many times party or their employees leak such valuable information for monitory gains and causes breach of contract of confidentiality.

Special techniques such as Social Engineering are commonly used to obtain confidential information.

The Hypertext Transfer Protocol (HTTP) is an application-level protocol that uses TCP as an underlying transport and typically runs on port 80. HTTP is a stateless protocol i.e. server maintains no information about past client requests.

HTTP Connections

1.     Non-Persistent

2.     Persistent

Before starting with persistent and non-persistent HTTP connection lets know what is a RTT.

RTT-> Time for a small packet to travel from client to server and back.

RTT= 2*propagation time

1. For a connection Persistent or Non-persistent it is sure that to initiate TCP connection one RTT is used.

So in order to know total file transmission time->

 total = 2RTT+transmit time

Non-Persistent Connection

1.     Without a parallel connection

2.     With parallel connection

Without parallel connection Non-Persistent

With parallel connection Non-Persistent

Persistent connection

1.     Non-Pipelined

2.     Pipelined

In Non-pipeline connection we first establish a connection which takes two RTT then we send all the objects images/text files that take 1 RTT each (TCP for each object is not required).

In Pipelined connection 2RTT for connection establishment and then 1RTT(assuming no window limit) for all the objects i.e. images/text.

Advantages of persistent connections :

Disadvantages of persistent connections :

HTTP Message Format

HTTP is based on the client-server architecture model and a stateless request/response protocol that operates by exchanging messages across a reliable TCP/IP connection.

An HTTP "client" is a program (Web browser or any other client) that establishes a connection to a server for the purpose of sending one or more HTTP request messages. An HTTP "server" is a program ( generally a web server like Apache Web Server or Internet Information Services IIS, etc. ) that accepts connections in order to serve HTTP requests by sending HTTP response messages.

HTTP makes use of the Uniform Resource Identifier (URI) to identify a given resource and to establish a connection. Once the connection is established, HTTP messages are passed in a format similar to that used by the Internet mail [RFC5322] and the Multipurpose Internet Mail Extensions (MIME) [RFC2045]. These messages include requests from client to server and responses from server to client which will have the following format:

 HTTP-message   = <Request> | <Response> ; HTTP/1.1 messages

HTTP requests and HTTP responses use a generic message format of RFC 822 for transferring the required data. This generic message format consists of the following four items.

·        A Start-line

·        Zero or more header fields followed by CRLF

·        An empty line (i.e., a line with nothing preceding the CRLF)

·        indicating the end of the header fields

·        Optionally a message-body

In the following sections, we will explain each of the entities used in an HTTP message.

Message Start-Line

A start-line will have the following generic syntax:

start-line = Request-Line | Status-Line

We will discuss Request-Line and Status-Line while discussing HTTP Request and HTTP Response messages respectively. For now, let's see the examples of start line in case of request and response:

GET /hello.htm HTTP/1.1     (This is Request-Line sent by the client)

HTTP/1.1 200 OK             (This is Status-Line sent by the server)

Header Fields

HTTP header fields provide required information about the request or response, or about the object sent in the message body. There are four types of HTTP message headers:

·      General-header: These header fields have general applicability for both request and response messages.

·      Request-header: These header fields have applicability only for request messages.

·      Response-header: These header fields have applicability only for response messages.

·      Entity-header: These header fields define meta-information about the entity-body or, if nobody is present, about the resource identified by the request.

All the above-mentioned headers follow the same generic format and each of the header field consists of a name followed by a colon (:) and the field value as follows:

message-header = field-name ":" [ field-value ]

Following are the examples of various header fields:

User-Agent: curl/7.16.3 libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3

Host: www.example.com

Accept-Language: en, mi

Date: Mon, 27 Jul 2009 12:28:53 GMT

Server: Apache

Last-Modified: Wed, 22 Jul 2009 19:15:56 GMT

ETag: "34aa387-d-1568eb00"

Accept-Ranges: bytes

Content-Length: 51

Vary: Accept-Encoding

Content-Type: text/plain

Message Body

The message body part is optional for an HTTP message but if it is available, then it is used to carry the entity-body associated with the request or response. If entity-body is associated, then usually Content-Type and Content-Length headers lines specify the nature of the body associated.

A message body is the one which carries the actual HTTP request data (including form data and uploaded, etc.) and HTTP response data from the server ( including files, images, etc.). Shown below is the simple content of a message body:

<html>

   <body>

  

      <h1>Hello, World!</h1>

  

   </body>

</html>

Next two chapters will make use of above explained concepts to prepare HTTP Requests and HTTP Responses.