the ability of a system to ensure that an asset can be used by any authorized parties

The main objective of ... is to ensure that authorized access to data when desired is achievable

The most dangerous availability attack

A service is said to be available if

when a theif steal your computer you lose the

if the thief looks at the pictures or documents stored in your computer you lost the

If the thief changes the contents of your documents then you lost the

set of circumstances that has the potential to cause loss or harm

a weekness in the computer system that can be exploited to cause harm or loss

bombs are an example of a threat to ...

a program that has a secret entry point

A specific type of trojan horse that can be used to spread infection from one computer to another

A program that overtly does one thing while covertly doing another

makes information accessible to unintended people or programs

..... concentrate mainly in addressing a vulnerability to reduce the probability of an attack or the impact of a threat

computer networks are both fragile and strong

A network removes most of the clues such as apperance, voice, context by which we recognize acquaintances

In some networks one or both end, intermediate points involved in a given communication maybe machines with only minimal human supervision

Many networks connect endpoints that are physically far apart. Althought not all network connection involv distance, the speed of communication is fast enough that humans usually can't tell whether a remote site is near or far

because the dimension of the distance is hidden users can't tell whether a remote host is in the next door or in a different country in the same way users they can't distinguish whether they are connected to which kind of node office,home,school, wherever

A network combines two or more possibly dissimilar operating systems, Threfore a network operating/control system is likely to be more complex than an operating system for a single computing system