Computer Network

A Computer Network is when two machines are linked together so that they can share files or folders. A computer connected to a network is known as a ‘work-station’.

Sharing hardware peripherals

A computer might be connecter to a printer. Sometimes they aren’t being used and just lie idle. A computer which isn’t connected to a network is known as a ‘stand-alone’. It would cost a lot of money for every computer to have its own printer in a school or an office. Most of the time the printer aren’t been used. In schools they join the computers together to form a network, so they are able to share one printer. This means that the printer is used more often and the money can be spent on buying a better quality printer.

Sharing files

In schools there is a folder called the ‘shared area’. This is where teachers put resources that they want students to access during the lesson. All students can open the resources and re save it in their own folders but they can’t change anything from the original copies in the shared area.

Log onto any workstation

At home, when you save your work, it always gets saved onto the hard disk on the computer/laptop that you were working on. If you want to open this file again, you CAN only open it by using the same computer/laptop. If you try to use a different computer/laptop you won’t be able to see the document because it has saved in the computer that you were working on. In schools, they have a network which will allow you to log on to any computer in the school and still get all of your files and folders. This is because the files haven’t been saved on the computer but they were saved on the file server. When you log onto the network with your user name, it tells the network who you are and it also finds your files and folders you saved in your user name.

Central backups

It is important to back-up your files regularly. Computer networks in school backs up everyone’s files and folder from the file server each evening after school closes.

Installation of Software

When installing new software in schools, the software is installed centrally so it can be available to all other computers.

Virus Checks

On the network anti-virus software runs centrally can check every computer at the same time.

Security

All the documents are saved in the school’s hard drives, although you log onto the computer to do the work even after you log off some else can go into that computer and see all your work and maybe delete or copy your work. In a Network only you can only see your documents and this helps to keep your documents safe.

Disadvantages of Network

Viruses Viruses can rapidly spread to all computers and could cause problems to people’s files.

Network Failure If the file server fails then no-one can access to their work through from the network. If the network failed in a company this would cost them extremely and very disruptive. If the network fails, this means that any computers that connected to that part of the network couldn’t access to their resources. This could be used as stand-alone machines.

Slow Service If many users log onto the network send things to be printed and open software applications and this may cause the network to slow down. In the network there is a limited amount of bandwidth.

Cost All the machines have to be connected to a network either by physical cables or even wireless technology. Other hardware like hubs, switches and router are often used.

Expert Support Required The Network needs a constant monitoring to make sure that the performance is maintained fully and that all of machineries are working properly. This requires a specialist staff like the network managers and technicians who will spend their time that the network works well. Without them, things would start to fail.

Local Area Network (LAN)

If the computers are fairly close to each other, like across the road or in the same buildings this would be joined together either by cables or wireless. These computers will form a LAN. After the computers are connected together in a LAN, many people can share and use the same resources at the same time. They can share files, hardware peripherals e.g. printer. They can use the LAN to communicate with each other by e-mail. Data can be transmitted very fast between the computers which are connected through the LAN. You need a user name and password to log onto the LAN. The user name identifies you to the file server and gives you the correct files. The password makes sure that user name does belong to you. Nearly all of the schools uses LAN network.

Wide Area Network (WAN)Offices, Shops, Factories that are in various locations around the world uses WAN network. Even though staffs work in different places, they can access to the same files no matter where they are. This would not be possible to connect computers in different buildings together using the LAN cables but for WAN network they can be connected via fibre optic cables, microwave links or satellite. By linking LAN network together, it is no longer local to one specific building, now it is a spread over a wide area. The largest WAN in existence is the Internet.

Hackers

A Hacker is a person who breaks codes to gain entry into an unauthorised computer. Hackers can do a massive amount of damage if they break into a computer. Stand-alone computers are safest as there is no connection for hackers to break into. Computers which are in a form of a network are in danger from the hackers. Some hackers often don’t steal or delete data but they enjoy the challenge of breaking the system. Still many hackers purpose is to steal valued data or delete data.

Data Theft

Data is the most important resource that any business has. Loss of data from hacking can have different consequences:

Can affect the business Can affect personal data May compromise data privacy

Physically Protecting Systems

Businesses use a variety of physical methods to protect their systems and important data. Some of these are:

Security Locks Using alarm systems and video cameras Keeping important data on a stand-alone machines instead of networks Keeping important computers in locked rooms.

Using Software to protect Systems

Many businesses can also use software to help protect their systems.Some of these methods are:

Firewalls - software that blocks access from outside and also to prevent data being sent out

User IDs and Passwords Activity or Audit logs – to track down who has been doing what on the systems

Legislation

To deal with hacking and computer fraud, a law was introduced in 1990 called ‘The Computer Misuse Act’Under this law, the offences could be dealt with:

1. Hacking – unauthorised access to any data held in a computer. Penalty is a maximum fine £2000 and a six month prison sentence.

2. Computer fraud and blackmail – Penalty is an unlimited fine and a maximum fine year prison sentence.

3. Viruses – impairing the operation of any program of data. Penalty is unlimited fine and a maximum five year prison sentence.

Malicious Software

What is a virus?

A Virus is a software program that is designed to copy itself over and over again for it to attach itself to other programs. Viruses can cause a huge amount of time wasted and financial loss for people and businesses. For example, the “Melissa” virus was so effective in spreading itself that many huge companies had to shut down their email systems until the virus could be restricted. Viruses do NOT damage the hardware but they affect the data and programs stored on the computer.

How do they spread?

The most common way of getting computer viruses are: Email attachments Downloading a file from a web page Infected web pages

Another way of getting viruses is from uploading infected files on to the computer from some kind of storage device are:

Memory Stick CD/DVD

It’s also possible to get viruses from computer through file sharing networks. There is no evidence that the computer has been infected with the virus and you might be unaware of it but after a while it causes something to go wrong.

How can they be removed?

Many Companies began to develop software to detect viruses and remove them. These were named as ‘anti-virus software’. There are many anti-virus programs available for wiping out viruses. They are:

Norton McAfee Sophos

The program will alert the user if it recognises a virus program and asks them if they want to remove the virus and destroy it from the system.

Advantages and Disadvantages of using Anti-Virus programs

Advantages Disadvantages The software will update itself

automatically or after you set it up for a specific date

When installing new software, the anti-virus software thinks that it is a huge virus has been uploaded and tries to remove it from the system by giving lots of alert. This is why when installing new software, the installation routines often advises that the anti-virus should be switched off during the installation.

Preventing infection

Viruses can be stopped by taking precautions including: To scan your system weekly by using anti-virus software By not opening attachments from people you don’t know at all By backing up your system regularly so that you can recover your work when

something happens to your work

Trojans

A Trojan is a program that says it’s useful for a computer game which in the first place you have upload but a Trojan does something with ill-intent.

A Trojan does: Track your keystrokes and send the details to a computer server. This is used to

capture your passwords. This will allow someone else to take over your computer whilst you are online. By capturing screen shots and send them to a remote computer, with an intent to

obtain confidential information.Worms

These are computer virus but they spread the virus on their own computer networks. They soak up computer time and bandwidth which makes the network slow down.

Adware / Spyware

These are designed to keep track on which adverts you click on and they send specific adverts to the browser. They are harmless but very hard to get rid of.

ICT Crime

There are different methods that criminals use through the internet to try and get your hard earned money. ‘Criminal activity directly related to the use of computers’ is also known as Computer Crime. For example:

To steal money To steal data or important information Damaging someone’s system

Theft of Money

On the Internet mainly paid through by credit cards or debit cards. Therefore thieves use stolen credit cards to purchase goods over the internet. Many supermarkets used to print credit card numbers but many supermarkets now print the last 4 digits of the credit card to make it harder to steal details. The Online companies now also check the address for the delivery is the same as the credit card owner. This makes it harder for the thief to use the stolen credit card to buy goods.

Theft of data

The most valuable product in any business is data. Data’s can be stolen either by physical theft of hardware or unauthorised access to the system e.g. hacking.

Fraud

There are many computer frauds committed in order to make some kind of money or financial gain. Some of the most common forms of computer fraud are:

Creating ‘spoof’ websites that look like the real website. For example, making a website that looks like the banks, and then getting you to enter your username and password so they can record it and use it for their purpose.

Posing as someone from an official organisation such as Bank Company in order to get your account details.

Piracy

Software Piracy is when copying software and film DVDs. Every piece of software, music CD or film DVD that we copy means that the developers are losing the profit for that item. By not paying for the item in the first place, the makers of the company will have less profit to reinvests in making the next one. It has estimated that if piracy could be cut by just 10% and then extra 40,000 jobs could be created in the IT industry.

Protecting yourself

Many Businesses use a range of physical methods to protect their systems and data. Some of these include are:

Security locks and smart cards Using alarm systems and video cameras Keeping important data on stand-alone machines Education of users

o Not to tell anyone their user names and passwordso To changed passwords regularly

Businesses also use software to help their systems. They are: Data encryption Firewalls

Activity logs, passwords

Legislation

The Computer Misuse Act was legislated in 1990 to deal with crimes such as hacking, computer fraud and viruses. These offences could be dealt with:

Hacking – unauthorised access to any data held in a computer. Could be fined a maximum of £2000 and a six month prison sentence.

Computer fraud and blackmail – There is a unlimited fine and a maximum of five year prison sentence.

Viruses – unauthorised modification of the contents to the computer. Unlimited fine and a maximum five year prison sentence.

http://www.teach-ict.com/gcse_new/protecting_systems/crime/miniweb/index.htm