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Beginners Guide to Computer Security

All computers, from the family home computer to those on desktops in the largest corporations in the country can be affected by computer security breaches.  This guide provides general overview of the most common computer security threats and the steps you can take to protect against these threats and ensure that your computer is both safe and cannot easily be used to attack other computers on a network or on the Internet itself.

Importance Of Security

While the Internet has transformed and greatly improved our lives, this vast network and its associated technologies have opened the door to an increasing number of security threats from which individuals, families and business must protect themselves. The consequences of attacks can range from the mildly inconvenient to the completely debilitating. Important data can be lost, privacy can be violated and your computer can even used by an outside attacker to attack other computers on the Internet.

Threats to Data

As with any type of crime, the threats to the privacy and integrity of data come from a very small minority. However, while a car thief can steal only one car at a time, a single hacker working from a single computer can generate damage to a large number of computer networks that can wreak havoc on our country's information infrastructure. Whether you want to secure a car, a home or a nation, a general knowledge of security threats and how to protect yourself is essential.


Viruses are the most widely known security threat because they often garner extensive press coverage. Viruses are computer programs that are written by devious programmers and are designed to replicate themselves and infect computers when triggered by a specific event. For example, viruses called macro viruses attach themselves to files that contain macro instructions (routines that can be repeated automatically, such as sending email) and are then activated every time the macro runs. The effects of some viruses are relatively benign and cause annoying interruptions such as displaying a comical message when striking a certain letter on the keyboard. Other viruses are more destructive and cause such problems as deleting files from a hard drive or slowing down a system. A computer can be infected with a virus only if the virus enters through an outside source - most often an attachment to an email or a file downloaded from the Internet. When one computer on a network becomes infected, the other computers on the network - or for that matter other computers on the Internet - are highly susceptible to contracting the virus.

Trojan Horse Programs

Trojan horse programs, or Trojans, are delivery vehicles for destructive computer code. Trojans appear to be harmless or useful software programs, such as computer games, but are actually enemies in disguise. Trojans can delete data, mail copies of themselves to e-mail address lists and open up computers to additional attacks. Trojans can be contracted only by copying the Trojan horse program to a computer, downloading from the Internet or opening an email attachment.


Web sites have come alive through the development of such software applications as ActiveX and Java Applets. These applications enable animation and other special effects to run, making web sites more attractive and interactive. However, the ease with which these applications can be downloaded and run has provided a new vehicle for inflicting damage. Vandals can take on the form of a software application or applet that causes destruction of various degrees. A vandal can destroy a single file or a major portion of a computer system.


Innumerable types of network attacks have been documented, and they are commonly classified in three general categories: (1) reconnaissance attacks, (2) access attacks, and (3) denial of service (DoS) attacks.

Reconnaissance attacks are essentially information gathering activities by which hackers collect data that is used to later compromise networks. Usually, software tools, such as sniffers and scanners, are used to map out and exploit potential weaknesses in home computers, web servers and applications. For example, software exists that is specifically designed to crack passwords. Such software was originally created for computer administrators to assist people who have forgotten their passwords or to determine the passwords of people that have left a company without telling anyone what their passwords were. Placed in the wrong hands, however, this type of software can become a very dangerous weapon. Access attacks are conducted to gain entry to e-mail accounts, databases and other confidential information. DoS attacks prevent access to all or part of a computer system. They are usually achieved by sending large amounts of jumbled or other unmanageable data to a machine that is connected to the Internet, blocking legitimate traffic from getting through. Even more malicious is a Distributed Denial of Service attack (DDoS) in which the attacker compromises multiple machines or hosts.

Data Interception

Data transmitted via any type of network can be subject to interception by unauthorized parties. The intercepting perpetrators might eavesdrop on communications or even alter the data packets being transmitted. Perpetrators can use various methods to intercept data. IP spoofing, for example, entails posing as an unauthorized party in the data transmission by using the Internet Protocol (IP) address of one of the data recipients.


Con artists have been perpetrating scam operations for decades. Now more than ever, the stakes are higher as they've got easy access to millions of people on the Internet. Scams are often sent by e-mail and may contain a hyperlink to a web site that asks you for personal information, including your password. Other times, scam e-mail may contain a solicitation for your credit card information in the guise of a billing request. There are ways to take proactive steps toward protecting yourself from scams on the Internet, such as never giving out your password, billing information or other personal information to strangers online. Because it is easy to fake e-mail addresses, be mindful of who you're listening to or talking with before you give out personal information. Don't click on hyperlinks or download attachments from people or web sites you don't know. Be skeptical of any company that doesn't clearly state its name, physical address and telephone number.


Spam is the commonly used term for unsolicited e-mail or the action of broadcasting unsolicited advertising messages via e-mail. Spam is usually harmless, but it can be a nuisance, taking up people's time and storage space on their computer.

Security Tools

Once you understand the threats, putting the proper safeguards in place becomes much easier. You have an extensive choice of technologies, ranging from anti-virus software packages to firewalls for providing protection. With all the options currently available, it is possible to implement proper computer security without compromising the need for quick and easy access to information.

Anti-Virus Software

Virus protection software can counter most virus threats if the software is regularly updated and correctly maintained. Anti-virus software relies on a vast network of users to provide early warnings of new viruses, so that antidotes can be developed and distributed quickly. With thousands of new viruses being generated every month, it is essential that the virus database be kept up to date. The virus database is the record held by the anti-virus package that helps it identify known viruses when they attempt to strike. The software can prompt users to periodically collect new data. It is essential to update your anti-virus software regularly.

Security Policies

Organizations both large and small need to craft computer security policies. Security policies can be rules that are electronically programmed and stored within computer security equipment as well as written or verbal regulations by which an organization operates. Written policies as basic as warning computer users against posting their passwords in work areas can often preempt security breaches. Customers or suppliers with access to certain parts of the network need to be adequately regulated by the policies as well.


Making sure that your computer system is password protected is the simplest and most common way to ensure that only those that have permission can enter your computer or certain parts of your computer network. However, the most powerful network security infrastructures are virtually ineffective if people do not protect their passwords. Many users choose easily remembered numbers or words as passwords, such as birthdays, phone numbers, or pets' names, and others never change their passwords and are not very careful about keeping them secret. The golden rules, or policies for passwords are:

  • Make passwords as meaningless as possible
  • Change passwords regularly
  • Never divulge passwords to anyone


A firewall is a hardware or software solution to enforce security policies. In the physical security analogy, a firewall is equivalent to a door lock on a perimeter door or on a door to a room inside of the building - it permits only authorized users such as those with a key or access card to enter. A firewall has built-in filters that can disallow unauthorized or potentially dangerous material from entering the system. It also logs attempted intrusions.