Case Study 3

In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. Name at least two of these problems. Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine? Explain your answer.

Technology has become the fastest growing environment here on earth. One concrete example of that technology is the computer. Computers or human-like machines have actually contributed to the development of the world. As technology arises, more and more machines are being developed. From a single user gear into a multi-user and multiprogramming processes. These things help us do multiple tasks in work, studies, and interests.

But then problems would never fade away. They would always arise. And as these things are continually growing, more and more problems are still increasing.

Things like this happen also in a multiprogramming and time-sharing environments. Some situations like having different users at the same time may result to various security problems

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But first, let us discuss what is multiprogramming and time-sharing?

In using computers, multitasking is a method by which we perform multiple tasks also known as processes at the same period of time and share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn.

In order to achieve the tasks performed by a single CPU, there are different scheduling strategies so that the jobs will be performed.

In multiprogramming systems, the running task keeps running until it performs an operation that requires waiting for an external event (e.g. reading from a tape) or until the computer's scheduler forcibly swaps the running task out of the CPU. Multiprogramming systems are designed to maximize CPU usage.

In time sharing systems, the running task is required to relinquish the CPU, either voluntarily or by an external event such as a hardware interrupt. Time sharing systems are designed to allow several programs to execute apparently simultaneously. The expression 'time sharing' was usually used to designate computers shared by interactive users at terminals.

One of the security problems that would happen is when he would copy some of your files, delete or change it.

 An example is when the other user may overwrite your files. This would occur at some point when you already finished the first job and you are now working with your second job, but the other user had already finished the job that you are currently doing and is starting to work with your first job, this thing may lead to mixing of programs and result to error. This may also corrupt your files and would let you start your job all over again. This kind of state may lead to a failing work, unfinished jobs and damaged files and lesser memory.

The other user of your system may copy some of the files or programs and/or memory space you have. If he found a folder in your system that he might use in some other time, he would have a duplicate with it and make use of it in other instances.

The other user may also delete or accidentally delete the files you have most especially when he would think that he will never need it anymore.

The second problem is the sharing of your systems resources that may result to deficient memory.  As we all know multiprogramming is a technique that allows a single processor to process several programs residing simultaneously in main memory and interleaving their execution by overlapping I/O request with CPU request. It attempts to increase CPU utilization by always having something for the CPU to execute. The system switches among the programs for efficient processing and minimal idle time.    

When multiple programs are present in memory, an ill-behaved program may (inadvertently or deliberately) overwrite memory belonging to another program, or even to the operating system itself.

Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine?

A time-share machine allows multiprogramming processes and multi-tasking at the same time. One example of this is the personal computer and laptops. They are skilled to do multiprogramming skills simultaneously.

In this kind of situation, users share the system simultaneously. One example is when the other person in your group has all the files in his laptop and in order to work with your programs faster, you remote your laptop with his. This will allow you to view his desktop and all the files within his system. You could also manage to change his files since you are also working with his system. This kind of situation may lead to various security problems most especially on your personal files and of the things that you are currently working upon.

While a dedicated machine is a computer that services one primary function or task. For example is a computing device that has a built-in computer that is solely dedicated to compute numbers. Dedicated and time-share machine differs with each other when it comes to capabilities same as it would never have the same degree of security.