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OSI Model Essay

This research paper provides information on using ASP for ERP hosting. The paper is divided into four major areas. The first area defines and briefly describes the term of The Enterprise Resource Planning (ERP) system. The second area defines and briefly describes the term of Application Service Provider (ASP). The third area provides information on how ERP can be used through ASP. This area mentions architecture, implementation, and benefits from using ERP through an ASP.

The last area shows an example of an organization that has successfully implemented ERP system through ASP. Introduction Everyone has a door in their house which is usually locked. You cannot open the door without the right key. Have you ever seen a sign in a store that says “employees only”? In these two cases, the locked door and the sign on the door are like protection for your space, and it also shows who is allowed to go through the door and who is not. That is kind of what a firewall is.

This paper will show you what a firewall really is in the computer domain, how it works and the different types of firewalls that exist. Definition As defined on the internet, “a firewall is an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system. It is also a device or set of devices configured to permit, deny, encrypt, decrypt, or proxy all computer traffic between different security domains based upon a set of rules and other criteria”.

It is just like a wall which is usually made out of water, cement and other constituents that can stop somebody from going onto the other side or a better analogy would be a net that can let water through as an authorized item and is able to stop everything else such as fish and other sea animals. History of firewalls The term “firewall” originally meant a wall to confine a fire or potential fire within a building. The firewall technology itself emerged in 1980 while the internet was still a new technology; and as the internet technology internet was growing, the firewall technology started growing along with it.

Why a firewall? Think of this. Did your dad ever tell you where he kept all his money? May be he did, and you probably heard him saying or talking about a bank account too. He knows that his money is safe when it is in the bank and he can get to it anytime he wants and money cannot be taken out of his account unless he has authorized the transfers. The same way, a computer system needs protection so that the important data it contains will not be destroyed by an unauthorized person and also ensures that it will work properly.

But, to really understand the importance of the firewalls, you should first know the main functions surrounding your computer. In other words, what can you use your computer for? You can use your computer to save important files in its memory(which is a kind of an electronic space where you can store data) or communicate with someone else through the internet or create documents. With all the tools gathered, your computer should be able to function properly and do all those tasks for you.

Unfortunately, there are some people out there that for one reason or another, are trying every day to steal the data on your computer or make it work improperly. And, this is the reason you need a firewall; the same reason the security guard stands in from of the bank to protect the bank against robbery. Types of Firewall Firewalls can be categorized into three basic types. – Packet filters – Application Gateways / Proxy – Stateful Inspection Packet filters This type of firewall will perform its action by inspecting everything from the internet before it gets into your computer.

Now, in your house, think of packet filter firewall as a security guard. Your dad or your mom have their rules and always tell you what to do; you have to do your home work, you have to go to bed at 9pm, you have to eat vegetables or else, no dessert for you, and so on. However, they love you so much that they hire a security guard to protect you 24/7, and he will never go anywhere. Your parents also ask a security guard not to let anyone get into the house without their permission. To do so, a security guard is given a list of people who can and cannot enter the house, this list called Access Control Lists (ACLs).

Application Gateways / Proxy You parents realize that one security guard is not enough, and they want to ensure that the house is a safe place for you. Your parents call the security guard company and hire more security guards. The company suggests your parents choose its best system available called Application Gateways, also called Proxy. Your parent accepted the offer; a big gate with the security room is built in front of your house in no time. Everyone who wants to get into the house will have to go through this security room and has his Identification (ID) checked.

This ID can verify who he is, where he comes from, and what business he has at your house. If an ID is valid, a person will be searched to see if he carries weapons. By doing so, you can now be sure that you are safer than ever before. Stateful Inspection There is another type of body guard called Stateful Inspection. Not only will he follow Access Control Lists (ACLs) as mentioned before, but he also takes a picture of visitors to keep on record. The next time this visitor comes, he will be recognized by the picture on his file. . How the Firewall works? The major job of a firewall is to keep anything in your computer secured.

It works like a traffic light. If you are driving a car or riding a bike, you start to slow down at traffic lights and come to a complete stop if the light is red. Red lights mean you are not allowed to cross, and if it is green then you are good to go. Firewalls stand in the middle between the system and the internet. It stops or alerts you if you have anyone trying to invade your personal computer space. A firewall is like a security guard standing in front of a bar checking for IDs because you have to be twenty-one years-old in order to get into the bar.

A firewall stands between two networks, and the network is just like a bar. Outside a bar is a place where everybody can sit or stand regardless of how old they are. Similarly, outside the network is where all the traffic flows, bad or good. However, inside the bar are the customers who are of legal age. Compare this to your personal computer network that is not for everyone; it is only for the traffic that you want to be in your computer. The traffic has to meet certain criteria so that firewalls can allow them into your computer.

Those who meet the criteria are let in by the firewall and those who do not meet the criteria are kept out. If bad traffic is enters your computer illegally, it rings a bell to let you know that something has entered inside without your knowledge. Firewall layers A firewall is working on the third of the seven layers of OSI Model. It is a network layer. This is where the traffic passes into the network. OSI stand for Open System Interconnection and it is defined as a networking structure which is responsible for implementation of the traffic within the seven layers.

To clarify the function of the seven layers in the OSI Model, let us replace OSI with a house that has seven rooms: three small bedrooms for kids, a family room, a room for the family library, and two bathrooms, one for a shower and other for a toilet. These rooms each have a different use. For example, someone living in that house cannot use the shower room for a toilet. He/she has to go to the toilet room because the shower room is designed for showers only. Each of these bedrooms has its own duty too. The same thing is true of the seven layers of the OSI model. Each layer has its own duty to perform.

The master room is for mom and dad to sleep. Kids are not allowed to sleep in mom and dad`s room because the function of that room is only for dad and mom to sleep. OSI layer seven`s function is to give the last computer’s user a service; an example would be giving an email account to a certain user. Conclusion In conclusion, we will say that the firewall technology is widely used in the world of technology today. Firewalls appear sometimes as one component or as a combination of components that are really sophisticated in order to meet the requirements and to protect the user against the continuing threats from the internet world.


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