Chapter 4 - Computer networks

Network security

-Access to networks and data can be kept secure by authenticating users with their user ID and password. -Unauthorised access can be reduced by allowing different users different levels of access.Data encryption gives another level of data security

(LANs) Bus network

-All networked devices are connected to a cable known as a bus. -Any break in the bus causes serious problems. -Needs terminators at each end of the bus. -Superseded by star networks.

Wide area networks (WANs)

-Computers in a WAN are oft en connected to each other using communication media provided by a third party. An example would be a telephone company providing links via telephone cables or via broadband facilities. -A WAN may interconnect several LANs. If a LAN needs to be connected to a WAN a special gateway needs to be set up.

Advantages of the internet

-Easy communication and data exchange with other people -Enables people to work from home (teleworking) -A vast amount of information can be accessed -Up-to-date information available immediately

(LANs) Star Network

-Every networked device has its own physical link with the hub or switch. -This means that if one network device crashes, or there is a fault in the network cable, all the other stations are still able to function correctly. -This type of network is fast, reliable and inexpensive and is the most common.

Dangers from the Internet

-Hackers (Prevented by using firewall software) -Viruses (presented by anti-virus programs) -Undesirable adult material

Disadvantages of the intranet

-Low volume and variety of information -Tend to have a single view

Disadvantages of the Internet

-Much of the internet isn't checked and may be wrong -A large amount of undesirable material is readily available -Data can be intercepted and put to illegal use -Risk of hackers or viruses being able to damage your computer -Privacy and security of data difficult to maintain

Disadvantages of a LAN

-Security measures are needed. -Additional hardware means that there is more that could go wrong.

Advantages of a LAN

-Share hardware devices like printers, servers, CD-ROM drives, WAN communication links. -Share data and communicate with other users. -Share software - each application package only has to be loaded onto the file server and not onto every workstation

Principles of the Data Protection Act

1. Data must be fairly and lawfully processed. 2. Data can only be processed for the stated purpose. 3. Data must be adequate, relevant and not excessive. 4. Data must be accurate. 5. Data must not be kept longer than necessary. 6. Data must be processed in accordance with the data subject rights. 7. Data must be kept secure. 8. Data must not be transferred to another country unless they have adequate protection.

Bridge

A bridge allows two different types of network to communicate with each other

What is a network

A network is two or more computers, or other electronic devices, connected together so that they can exchange data. For example a network allows computers to share files, users to message each other and share Resources

The Intranet

An intranet is similar to the Internet but is limited to a particular organisation. It will be tightly controlled by the organisation.

(LANs) Network shape

Computers can be linked together to form networks. The shape of the network is determined by the way in which the links are made

What is encryption

Encryption is the process of converting information into a form that is meaningless to anyone except holders of a 'key'

Router

Hardware allowing computer to access the Internet using a phone line

Modem (Modulator/Demodulator)

Hardware used to change analogue signals from the phone line into digital signals needed by the computer, also used to change the signals from digital to analogue

LAN

Local Area Network - the computers are all in the same building or on one site, connected together by hubs and switches using cables

Ways websites strengthen security when logging in

Security Question: • Users may be asked to answer security questions related to their account. • Typical questions includes mothers maiden name. Personal Image: • QNB (Qatar National Bank) require users to identify an image when they log in on the website for online banking. . • Users will have to confirm if the image shown is one they selected as their account image.

Hubs and Switches

Similar hardware in a network which distribute signals between the server and the individual PCs. (A hub sends the signal to all the devices on the network and only one individual PC will accept the signal. A switch sends the signal to only the one individual PC by specifying the individual address)

Browser

Soft ware used to find and look at information on the web. Each web page has its own unique address known as a Universal Resource Locator (URL)

The Internet

The Internet is a communications system linking computers across the world - a network of networks. Data is passed from computer to computer, from server to server, until the required destination is reached.

Advantages of intranets

Tight control by the owning organisation so that: -views posted are relevant -information will be useful, accurate and relevant -the amount of information is limited so it is easier to search -safety from inappropriate material -less susceptibility to hackers and viruses

Video Conference

Webcam and microphone used to allow people to communicate with each other

WAN

Wide Area Network -the computers are spread over a large geographical area connected to each by using fibre-optic cable, telephone lines, radio transmitters or satellite links

WLAN

Wireless Local Area Network - devices are connected by wireless rather than cable

Define Bluetooth

a wireless networking technology designed for very short-range connections

Define Wi-Fi

a wireless networking technology makes it possible to connect devices with a wireless connection to a network or to a single computer

Biometrics (finger prints, retina scans, iris scans, face scans, vocal recognition)

• Biometrics use unique data. • Only the person with the biometric features can access the network. • Can not copy/replicate biometric data

Advantages of using Networks

• Easily share files and data. • Share resources such as printers and Internet connections. • Communicate with other network users (e-mail, instant messaging, video-conferencing, etc.) • Store data centrally (using a file server) for ease of access and back-up. • Keep all of our settings centrally so we can use any workstation.

Disadvantages of using Networks

• Greater risk of hackers. • Greater risk of viruses (spreading and disabling network). • The significant cost of extra equipment. • When the network is down computers can not be used as standalone computers. • Print queues can be long.

Magnetic Swipe Cards

• Swipe cards are used to gain access to the system by swiping the card into the reader. • Swipe cards are quite easy to use and update. • Could also be used to gain entry into a room (hotel room).

Transaction Authentication Number (TAN)

• TAN is used by online banking services. • User will insert their bank card into the TAN reader which will then provide a code which will need to be entered to complete a transaction.

Two factor Authentication

• Two Factor Authentication involves the user typing in their password and then typing in a code. • The code is sent to the registered phone number of the account as a text. • If an unauthorised attempt is made to log into an account then the text message will alert the user.

Give ways which you ca set up a strong password

• Use at least 8 characters • Includes letters and numbers • Avoid using names or words which could be easily guessed. • Use upper and lower case letters.