Computer Fundamental (part 4)

Internet Services
The main services used on the internet include:
Web browsing - Supported by the HTTP protocol, this functions allows users to view web pages using a web browser.

E-mail - Allows people to send and receive electronic messages.

Instant Messaging [Chatting]: Instant messaging using internet.

E-Commerce: Online shopping/trade.

Telnet : Remote Login service.

E-learning : Online Education.

Other lesser used services include telnet (allows remote login to computers), FTP (Allows quick file transmission to remote computers), and gopher (An early form of text based form of reading internet documents which is rarely used today).

Accessing the Internet
People use an internet browser to access web pages that are available across the internet. Internet browsers include Microsoft Internet Explorer, Netscape Navigator, Mozilla, and others.

Web pages are created in a marked up form of text file called HTML (Hyper-Text Markup Language). The markup within the text indicates document structure showing where paragraphs begin and end, what items are in a list, headers, tables and other document structure.

When people are browsing of surfing the internet, they usually go from place to place by clicking on links. These links are locations for specific pages and indicate the three things:
1. Protocol being used such as http or

2. The domain that the web page is found on. This will point to a specific organization's or company's web server.

3. The location of the page on the server including the directory path and file name.

An example link is "". In this case http is the protocol being used the domain indicates where the organization's web server is, and the /html/dos/dos02_02.php "part of the string indicates the folders the file is in and the name of the file.
These links are sometimes called hyperlinks or URLs (Uniform Resource Locators)

Computer Viruses
This document covers the basics on computer viruses. Please take some time to peruse the information to obtain an overall understanding of the concern and how to safeguard yourself from the dangers of viruses.

What is a Virus?
A computer virus is one of thousands of programs that can invade computer systems (both IBM PC and Macintosh) and perform a variety of functions ranging from annoying (e.g., popping up messages as a joke) to dangerous (e.g., deleting files or destroying your hard disk). Trojan horses or worms are specific types of clandestine programs (loosely categorized as viruses) and can be just as dangerous. For simplicity's sake, future mention of viruses in this document will refer to viruses, trojan horses, and worms taken as a whole.

How Do Viruses Spread?
Computer viruses are programs that must be triggered or somehow executed before they can infect your computer system and spread to others. Examples include opening a document infected with a "macro virus," booting with a diskette infected with a "boot sector" virus, or double-clicking on an infected program file. Viruses can then be spread by sharing infected files on a diskette, network drive, or other media, by exchanging infected files over the Internet via e-mail attachments, or by downloading questionable files from the Internet.

At the beginning of February, 2001, UH Information Technology Services installed an e-mail virus scanner on its mail gateway. This software is able to filter out viruses sent as e-mail attachments before it is received by ITS customers. However, it is not foolproof and new and unrecognized viruses may still be able to get through the filter.

Basic types of viruses
File viruses
File viruses, also known as parasitic or executable viruses, are pieces of code that attach themselves to executable files, driver files or compressed files, and are activated when the host program is run. After activation, the virus may spread itself by attaching itself to other programs in the system, and also carry out the malevolent activity for which it was programmed. Most file viruses spread by loading themselves in system memory and looking for any other programs located on the drive. If it finds one, it modifies the program’s code so that it contains and activates the virus the next time it’s run. It keeps doing this over and over until it spreads across the system, and possibly to other systems that the infected program may be shared with. Besides spreading themselves, these viruses also carry some type of destructive constituent that can be activated immediately or by a particular ‘trigger’. The trigger could be a specific date, or the number of times the virus has been replicated, or anything equally trivial. Some examples of file viruses are Randex, Meve and Mr Klunky.

Boot sector viruses
A boot sector virus affects the boot sector of a hard disk, which is a very crucial part. The boot sector is where all information about the drive is stored, along with a program that makes it possible for the operating system to boot up. By inserting its code into the boot sector, a virus guarantees that it loads into memory during every boot sequence. A boot virus does not affect files; instead, it affects the disks that contain them. Perhaps this is the reason for their downfall. During the days when programs were carried around on floppies, the boot sector viruses used to spread like wildfire. However, with the CD-ROM revolution, it became impossible to infect pre-written data on a CD, which eventually stopped such viruses from spreading. Though boot viruses still exist, they are rare compared to new-age malicious software. Another reason why they’re not so prevalent is that operating systems today protect the boot sector, which makes it difficult for them to thrive. Examples of boot viruses are Polyboot.B and AntiEXE.

Multipartite viruses
Multipartite viruses are a combination of boot sector viruses and file viruses. These viruses come in through infected media and reside in memory. They then move on to the boot sector of the hard drive. From there, the virus infects executable files on the hard drive and spreads across the system. There aren’t too many multipartite viruses in existence today, but in their heyday, they accounted for some major problems due to their capacity to combine different infection techniques. A well-known multipartite virus is Ywinz.

Macro viruses
Macro viruses infect files that are created using certain applications or programs that contain macros. These include Microsoft Office documents such as Word documents, Excel spreadsheets, PowerPoint presentations, Access databases and other similar application files such as Corel Draw, AmiPro etc. Since macro viruses are written in the language of the application and not in that of the operating system, they are known to be platform-independent—they can spread between Windows, Mac and any other system, so long as they are running the required application. With the ever-increasing capabilities of macro languages in applications, and the possibility of infections spreading over networks, these viruses are major threats. The first macro virus was written for Microsoft Word and was discovered back in August 1995. Today, there are thousands of macro viruses in existence—some examples are Relax and Bablas.

Network viruses
This kind of virus is proficient in quickly spreading across a Local Area Network (LAN) or even over the Internet. Usually, it propagates through shared resources, such as shared drives and folders. Once it infects a new system, it searches for potential targets by searching the network for other vulnerable systems. Once a new vulnerable system is found, the network virus infects the other system, and thus spreads over the network. Some of the most notorious network viruses are Nimda.

Email Viruses
An email virus could be a form of a macro virus that spreads itself to all the contacts located in the host’s email address book. If any of the email recipients open the attachment of the infected mail, the virus spreads to the new host’s address book contacts, and then proceeds to send itself to all those contacts as well. Email viruses can infect hosts even by previewing the infected email in a mail client.

How to Protect Yourself from Virus?
Virus Protection
A virus may or may not present itself. Viruses attempt to spread before activating whatever malicious activity they may have been programmed to deliver. So, viruses will often try to hide themselves. Sometimes there are symptoms that can be observed by a trained casual observer who knows what to look for (but, don't count on it).

Virus authors often place a wide variety of indicators into their viruses (e.g., messages, music, graphic displays). These, however, typically only show up when the virus payload activates. With DOS systems, the unaccounted for reduction of the amount of RAM known to be in the computer is an important indicator resident viruses have a hard time getting around. But, under Windows, there is no clear indicator like that. The bottom line is that one must use anti-virus software to detect (and fix) most viruses once they are on your system.

Your main defense is to detect and identify specific virus attacks to your computer. There are three methods in general use. Each has pros and cons and are discussed via these links. Often, a given anti-virus software program will use some combination of the three techniques for maximum possibility of detection.

With dangerous viruses on the network, what can computer users do to protect their systems? Here are just a few hints:
• Be sure to install an anti-virus software program (see the next section) to guard against virus attacks. Also, be sure you turn on the scanning features. It can't protect you if it's not enabled.

Practice caution when working with files from unknown or questionable sources.

• Do not open e-mail attachments if you do not recognize the sender (though you may also receive viruses from people you know). Scan the attachments with anti-virus software before opening them.

Download files only from reputable Internet sites, and be wary when exchanging diskettes or other media with friends.

• Scan your hard drive for viruses monthly.

Even with these precautions, new viruses may find ways to enter your computer system.

Data security
Data security is the means of ensuring that data is kept safe from corruption and that access to it is suitably controlled. Thus data security helps to ensure privacy. It also helps in protecting personal data.

You may loose your data due to:-
Data corruption
It refers to errors in computer data that occur during transmission or retrieval, introducing unintended changes to the original data. Computer storage and transmission systems use a number of measures to provide data integrity, the absence of errors.It refers to errors in computer data that occur during transmission or retrieval, introducing unintended changes to the original data. Computer storage and transmission systems use a number of measures to provide data integrity, the absence of errors.

Data loss during storage has two broad causes: hardware and software failure. Head crashes and general wear and tear of media fall into the former category, while software failure typically occurs due to bugs in the code.

If an uncorrectable data corruption is detected, procedures such as automatic retransmission or restoration from backups can be applied. RAID disk arrays, store and evaluate parity bits for data across a set of hard disks and can reconstruct corrupted data upon of the failure of a single disk.

Data theft
It is a growing problem primarily perpetrated by office workers with access to technology such as desktop computers and hand-held devices, since employees often spend a considerable amount of time developing contacts and confidential and copyrighted information for the company they work for they often feel they have some right to the information and are inclined to copy and/or delete part of it when they leave the company, or misuse it while they are still in employment.

Care of Your Computer
To keep your computer running smoothly and to ensure that it has a long and productive life, follow these tips.
Keep the computer away from heat sources (like radiators and heat registers). Heat is a computer's enemy.

There is a fan built into the back of the CPU case. Keep this unobstructed and clean. A vacuum cleaner nozzle with a brush attachment is a useful fan cleaning tool.

Don't spill liquids on any part of the computer. Liquids spilled on the keyboard or mouse might cause all kinds of electrical problems.

Clean the keyboard with a vacuum cleaner nozzle equipped with a brush tool.

Periodically clean the air vents on the side and back of the monitor with the vacuum brush.

Keep the monitor screen clean with a soft cloth. Use no detergents, chemicals or soaps. It works best if you clean the monitor when it is off. Otherwise, static electricity can compete with your cloth for the dust and grime.

Wipe off the keyboard keys with a soft cloth dampened with rubbing alcohol or other mild cleanser. Washing your hands before using the keyboard will keep it cleaner. Eating greasy finger foods while using the computer is not recommended.

About once a year, unhook the CPU case, take it outside (on a nice clear warm day), remove the case cover and take a look inside. If it has accumulated a lot of dust, cobwebs, and grit, you might want to invest in a can of compressed air and give it a good blast to clean it. Unless you know what's what, you shouldn't probe around with your fingers. Static discharges can zap sensitive electronic components.

Introduction to Computer Ethics
The introduction of the World Wide Web in 1990 has catalyzed the expansion of the Internet, which is still growing today at unprecedented rates. The recent growth of the Internet has resulted not only in an increase in the amount of available knowledge, but in an increase in the problems inherent to its usage and distribution. It has become clear that traditional rules of conduct are not always applicable to this new medium, so new ethical codes are now being developed.

Ethics, in the classical sense, refers to the rules and standards governing the conduct of an individual with others. As technology and computers became more and more a part of our everyday lives, we must understand that the problems that have always plagued business and conduct will continue to be a problem. In fact, a new medium can provide even more difficult questions of judgment. In other words, since the introduction of the World Wide Web, the definition of ethics has evolved, too. A new type of ethics known as computer ethics has emerged. Computer ethics is concerned with standards of conduct as they pertain to computers.

Why do we need computer ethics?
• the growth of the WWW has created several novel legal issues

• the existence of new questions that older laws cannot answer

• traditional laws are outdated/anachronistic in this world

• a more coherent body of law is needed to govern Internet and computers

Three of the more pressing concerns in computer ethics today are questions of copyright, privacy, and censorship, all of which are discussed in greater detail in the following three sections. Other problems exist as well, though. One problem is that many domain names ( are being bought and sold to the highest bidder. For example, recently a man bought the name and auctioned it off. Many people are purposely buying up company names and selling them to those companies at outrageous prices. President Clinton calls these people 'Squatters' and wants to pass a law forbidding them to buy up already existing company names. Is this fair? Don't these people have a right, under capitalism, to make money this way? Or is it near-blackmail?

Many people have been tricked my e-mail scams, claiming that they will make you a millionaire. It is the same sort of pyramid scheme that exists over telephone or mail, but no laws covered it for a while. Also, many email chain letters have allowed urban legends to spread at an accelerated rate and created alarm over hoaxes concerning many food and drug products. These emails only bog down email systems and servers, but do not seem to be ending. Some advertisers also email unsolisisted ads to email users, in a practice known as spamming.

Computers present us not only with vast new potential in technology, but also in ethics. Morality must play catch-up to technology that has leap-frogged ahead. Without a knowledge of computer ethics, you will not be fully equipped to enter the new world of online society - and you will need to enter that world, whether you choose a career in art, programming, business, or anything else.

Basic Computer Terms
Bit - A binary unit of data storage that can only be a value of 0 or 1.

BIOS - BIOS stands for Basic Input/Output System and it is a low level program used by your system to interface to computer devices such as your video card, keyboard, mouse, hard drive, and other devices.

Boot - A term used to describe what happens to a computer when it is turned on, the operating system begins to run, and then the user is able to use the computer successfully.

Byte - 8 bits of data which has a possible value from 0 to 255

CD-ROM disk - A disk with about 640Mb of storage capacity which are more commonly read than written to.

CD-ROM drive - The hardware component that is used to read a CD-ROM or write to it.

Crash - A common term used to describe what happens to a computer when software errors force it to quit operating and become unresponsive to a computer user.

Driver - A specially written program which understands the operation of the device it interfaces to, such as a printer, video card, sound card or CD ROM drive. It provides an interface for the operating system to use the device.

File - A collection of data into a permanent storage structure. Stored on a permanent storage media such as a computer hard drive.

Firmware - Software written into permanent storage into the computer.

Floppy disk - A low capacity storage media which can be written to as easily as it is read.

Floppy Drive - The hardware component that is used to read or write to a floppy disk.

Hardware - Describes the physical parts of your computer which you can physically touch or see such as your monitor, case, disk drives, microprocessor and other physical parts.

Internet - A network of networks which incorporate a many organizations, physical lines, the ability to route data, and many services including email and web browsing.

ISP - Internet Service Provider is an organization that provides the ability to connect to the internet for their customers. They also usually provide additional services such as e-mail and the ability to host web sites.

MIME - multipurpose internet mail extension

Memory - Used to provide the temporary storage of information function.

Network - A general term describing to the cables and electronic components that carry data between computers. It is also generally used to refer to the server computers that provide services such as printing, file sharing, e-mail, and other services.

Operating System - The core software component of a computer providing the ability to interface to peripheral and external devices along with program functions to support application programs.

Parallel - A data transmission method where data is sent on more than one line at a time. This may be any number of bits at a time, but is usually one word at a time (two bytes) or possibly three bytes at a time.

Protocols - A standard method used for communications or other internet and network functions.

Security flaw - A software bug allowing an attacker a method to gain unauthorized access to a system.

Serial - A data transmission method where data is sent on a single line and one bit is sent at at a time. This is similar to a line which one item must come one after another

Software - Describes the programs that run on your system.

SPAM - A term used to describe junk and unsolicited e-mail

Storage Media - A term used to describe any magnetic device that computer data can be permanently stored on such as a hard drive or floppy drive.

URL - Uniform Resource Locator is the term used to describe a link which points to a location of a file on the internet.

Virus - A program that runs on a system against the owner's or user's wishes and knowledge and can spread by infecting files or sending itself through e-mail

Vulnerability - Software errors that allow some kind of unauthorized access when they are used or exploited.

Word - Two bytes or 16 bits of data with a possible unsigned value from 0 to 16535.

Worm - A term used to describe an unwanted program that uses system or application vulnerabilities to infect a computer without the user doing anything but connecting to an infected network.

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