Intranet

The term “Intranet” is used to describe a network of personal computers (PC) without any personal computers on the network connected to the world outside of the Intranet. The Intranet resides behind a firewall; if it allows access from the Internet, it becomes an Extranet. The firewall helps to control access between the intranet and Internet so that only authorised users will have access to the Intranet. Usually these people are members of the same company or organisation. Like the Internet itself, intranets are used to share information. Secure intranets are now the fastest-growing segment of the Internet because they are much less expensive to build and manage than private network based on proprietary protocols.

Extranet

Extranets are becoming a very popular means for business partners to exchange information. An Extranet is a term used to refer to an intranet that is partially accessible to authorised outsiders. Privacy and security are important issues in extranet use. A firewall is usually provided to help control access between the Intranet and Internet. In this case, the actual server will reside behind a firewall. The level of access can be set to different levels for individuals or groups of outside users.

3.0         Internet Access

In order to have access to the vast resources on the Internet, you need to connect your computer to a computer system that is already on the Internet, usually one run by an Internet Service Provider (ISP). There are four major ways of connecting a client (user) computer to the vast resources on the Internet; these are by a dial-up connection using a telephone line or an Integrated Services Digital Network (ISDN), a Digital Subscriber Line (DSL), a cable TV connection or a satellite connection. While rural users may consider installing a satellite dish for Internet connections, urban users may have access to wireless connections. In most offices, users connect their computers via a local area network (LAN) connected to the Internet. Similarly, in many home, users are beginning to connect their computers into Internet-connected LANs, too. The Dial- up access gives a low speed connection to the Internet. High-speed Internet connections, which include DSL, ISDN, leased lines, cable Internet, and satellite, are called broadband connections.

3.0.1    Word Wide Web (WWW)

The WWW is a system of interlinked hypertext documents accessed via the Internet. The web browser is used to access the web pages that may contain text, images, videos, and other multimedia pages. The WWW use a protocol called HTTP-hypertext transfer protocol.

The HTTP defines how messages are formatted and transmitted, and the actions the web servers and other browsers should take in response to the various commands are also determined by the HTTP.

There are two types of website called the static and dynamic pages. The static website/page is a one that has web pages on the server in the format that is sent to a client web browser which is popularly called the front end design. The dynamic website is one that changes or customizes itself automatically basic on certain criteria which is equally called backend design.

3.0.2    Electronic Mail (Email)

The electronic mail is one of the fastest ways of sending information from one region to another via the computer and other electronic devices. You can communicate with one person at a time or thousands; you can receive and send files and other information. The basic email functions include send and receive email messages, save your message in a file, print mail messages, reply to mail messages and attach a file to a mail message.

There are a number of webmail providers but the most popular ones are gmail, yahoo mail and Hotmail.

An e-mail message consists of three components namely:

(i) the message header (ii) the message envelop, and (iii) the message body.

The message header contains control information, including, minimally, an originator's email address and one or more recipient addresses. Usually descriptive information is also added, such as a subject header field and a message submission date/time stamp. The message body carries the data to be sent. The message‟s body property usually contains details associated with the message. In addition to the data part, messages carry details that assist in distinguishing messages and selectively receiving them. This detail is made up of a fixed number of fields, which is referred to as the message envelope. These fields are source destination tag communicator. To use email, you should have an email address, which is created by an Internet Service Provider or on a Website such as yahoo, Google, and hotmail. Most e-mail addresses are set up in this manner: your username, followed by “@” (at) symbol, and then a domain name (for instance, .com, .edu.,.net, or .org). When you send e-mail to others, Simple Mail Transfer Protocol (SMTP) is used. When you receive e- mail, Post Office Protocol (POP, currently POP3) and Internet Message Access Protocol (IMAP) can be used.

Fig. 1.2: Google Mail Interface

3.0.3    File Transfer Protocol (FTP)

FTP is protocol for exchanging files over the Internet used. It is used for moving files between hosts on a TCP/IP network. FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server as seen in figure 1.2

Figure 1.3 FTP

To achieve FTP, the user invokes one of two commands:

·         get: the command for transferring a file from another server to you own computer

·         put: the command for moving a file from your computer to another one.

3.0.4    Search Engine

A search engine is designed to search for information on the Internet. This presents the results in the form of a search results list. The search results can be qweb pages, images, videos, and other type of files. Examples include Google, Bing, and Mamma among others. One of the popular images is seen in figure 1.3.

Figure 1.4 Search Engine

3.0.5    Chatting

This is the other method of Internet conversation which enables the connection of people anywhere on the Internet.

Chart sessions allow many users to join in the same free-form conversation which is usually within a discussion topic. Examples of the charting software are MSN messengers, Yahoo messengers, IRC, pidgin, WhatsApp among others.

3.0.6    Video Conferencing

A video conferencing is a set of interactive telecommunication technologies which allow two or more locations to interact via two-way video and audio transmission simultaneously using the Internet. Examples include zoom, video WhatsApp, Google meet among others.

3.0.7        E-Commerce

E-commerce also called electronic commerce is the buying and selling of products or services over electronic systems such as the Internet. Some of the common applications which are used in e-commerce are domestic and international payment systems, group buying, automatic online assistants, online shopping and other tracking, online banking, shopping cart software among other terms. Example of the online marketing sites are amoze.com, ebay.com, aliexpress.com, konga.com, jumia.com among others as seen in figure 1.4

Figure 1.5 logo of some e-commerce sites

3.0.8    Dial-up Connection

Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a dialed connection to an Internet service provider (ISP) via telephone lines. The user‟s computer or router uses an attached modem to encode and decode Internet Protocol packets and control information into and from analog audio frequency signals, respectively. The term “Dial-up Internet access” was coined during the early days of computer

telecommunications when modems were needed to connect terminals or computers running terminal emulator software to mainframes, minicomputers, online services and bulletin board systems via a telephone line. To use a dial-up account, you need a modem. A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and demodulates such a carrier signal to decode the transmitted information. To distinguish dial-up modems from newer, high- speed modems, they are could also be called analog modems or dial-up modems. Most computers come with an internal modem and most ISPs support modems at speeds of

28.8 kilobits per second (Kbps) and 56 Kbps. With dial-up, you connect only when you want to use Internet services and disconnect (hang up) when you are done. This type of data transmission is similar to using the telephone to make a call. The client computer modem dials the preprogrammed phone number for a user‟s Internet Service Provider (ISP) and connects to one of the ISP‟s modems. Once the ISP has verified the user's account, a connection is established and data can be transmitted. The communication ends when either modem hangs up. Dial-up connections is not expensive (it costs no more than a local telephone call) but the speed is usually low at about 28kps – 46kps because of the limitations of analog phone lines and telephone company switches.

3.0.9 ISDN

Integrated Services Digital Network (ISDN) is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. It allows dial up into the Internet at speeds ranging from 64 to 128 kbps. For this connection to be available, telephone companies would have to install special ISDN digital switching equipment. The ISDN service intended for residential use is Basic Rate Interface (BRI). On one ISDN line, BRI provides two 64-Kbps channels, or B (bearer) channels, and one 16-Kbps channel, or D(data) channel. The D channel is mostly used for signalling such as to indicate that the line is busy. The B channels are where the action is. Two B channels can be combined to have a 128-Kbps line to the

Internet. This is roughly twice the speed of the fastest analogue modem, 56 Kbps. To connect to your ISP via ISDN you need to confirm the availability of the access and this will require you to have an ISDN adapter. ISDN lines are more expensive than normal phone lines, so the telephone rates are usually higher.

3.0.10    Cable TV Connection

This is a connection made to the Internet via a Cable TV modem. The modem is designed to operate over cable TV lines. Since the coaxial cable used by cable TV provides much greater bandwidth than telephone lines, a cable modem can be used to achieve extremely fast speed as high as 128 kbps to 10 mbps to the World Wide Web

. This combined with the fact that millions of homes are already wired for cable TV in developed countries has made the cable modem something of a holy grail for Internet and cable TV companies. The services offered are usually at low cost for unlimited, “always connected” access. However, there are a number of technical difficulties in this type of connection. The problem is that the cable network was designed to move information in one direction, from the broadcaster to the user. Downstream speeds have been very impressive such that the line can theoretically bring you data as fast as 30 Mbps but upstream speed depends on line quality. The Internet, however, is a two- way system where data also need to flow from the client to the server. In addition, it is

still unknown whether the cable TV networks can handle the traffic that would ensue if millions of users began using the system for Internet access. Large cable companies are spending money to upgrade their networks to Hybrid Fiber-Coaxial (HFC) to handle two-way traffic better. Smaller providers cannot afford the upgrade, so they have to use a phone line at 28.8 Kbps for upstream data. Another issue bothers on security and the need to either share or not share files amongst users.

3.0.11    Digital Satellite Connection

Digital Satellite Systems (DSS), or direct broadcast satellite, allows one to get Internet information via satellite. Satellite Internet systems are an excellent, although rather costly, option for people in rural areas where Digital Subscriber Line (DSL) and cable modem connections are not available. A satellite installation can be used even where the most basic utilities may be lacking, if there is a generator or battery power supply that can produce enough electricity to run a desktop computer system. The two-way satellite Internet option offers an always-on connection that bypasses the dial-up process. In a two-way satellite Internet connection, the upstream data is usually sent at a slower speed than the downstream data arrives. Thus, the connection is asymmetric. A dish antenna, measuring about two feet high by three feet wide by three feet deep, transmits and receives signals. Uplink speeds are nominally 50 to 150 Kbps for a subscriber using a single computer. The downlink occurs at speeds ranging from about 150 Kbps to more than 1200 Kbps, depending on factors such as Internet traffic, the capacity of the server. The main advantage of the Satellite technology over cable modems and DSL is accessibility. Satellite connections are faster than dial up and ISDN. Although it is not as fast as cable modems or DSL services, which both can provide more than megabits of bandwidth. In addition, cable and DSL access methods are cheaper. Figure 1.5 shows a Satellite connection to the Internet.

Equipment required for satellite connection includes installation of a mini-dish satellite receiver and a satellite modem. Satellite systems are

also prone to rain fade (degradation during heavy precipitation) and occasional brief periods of solar interference.