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Basic Security Concepts In Computer Network

Basic Security Concepts

You will see certain terms throughout this chapter, so it is best to become familiar with them before going any further
Threats
The entire point of computer security is to eliminate or protect against threats.
threat is anything that can cause harm. In the context of computer security, a threat can be
• A burglar.
• A virus.
• An earthquake
• A simple user error.
By itself, a threat is not harmful unless it exploits an existing vulnerability. Vulnerability is a weakness-anything that has not been protected against threats, making it open to harm.
For instance, an unlocked car is vulnerable to theft.
The vulnerability is meaningless unless a thief is in the neighborhood. But you probably always lock your car or park it in a safe place.
Degrees of Harm
That said, it’s important to realize that threats, and the harm they can cause, are a matter of degree.
If you live on top of a mountain, for example, there is probably no threat of flooding.
If you don’t use antivirus software, however, there is a very good chance that your computer will become infected, especially if it stays connected to the Internet.
Because you can gauge the degree of harm that different threats can cause, you can prioritize them.
That is, you can decide which threats are more likely to “get you” and take precautions against them.
When people think of the ways their computer system can be damaged, they may think only of damage to the hardware or the loss of data.
In reality, computer systems can be damaged in many ways.
And remember, you (the user) are part of the computer system. You, too, can suffer harm of various kinds, from the loss of important data, to the loss of privacy, to actual physical harm.
When protecting your computer system, it pays to think in the broadest possible terms about the types of harm that could affect you.
nasty virus or hacker can wipe out your programs as well as your data.
If your PC is connected to a network, other systems on the network could suffer similar problems.
Damages to your home or office-such as a fire or flood–can easily extend to your computer and everything stored on it.
Countermeasures
A countermeasure is any step you take to ward off a threat – to protect yourself, your data, or your computer from harm.
For example
• Regularly backing up your data is a countermeasure against the threat of data loss.
• A firewall is a countermeasure against hackers.
There are two classes of countermeasures. The first shields the user from
• personal harm such as threats to personal property
• confidential information
• financial records
• medical records and so forth.
The second safeguard protects the computer system from
• Physical hazards such as theft,
• Vandalism,
• Power problems,
• And natural disasters or attacks on the data stored and processed in computers.