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  • Created by: Amy
  • Created on: 05-04-13 09:57

Home Networks

Local area netowork or LAN - connects all computers so all rescources can be shared (internet, files, peripherals amd internet telephone services)

Netowork interface card (NIC) is needed to connect the computers to the network if you arent using Wi-Fi dongles

Routers- connects all PCs to the modem and gives them an internal IP address so that it 'knows' where to send the data

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Types of Network

Cable or wireless connection to router

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Network Security

Wireless is less secure. If you dont secure your wireless anyone can access it

Importance of security - when you access the internet you can see everyone around you's network meaning you can access it at their cost.

Ways of sercuring

  • Changing the defualt admin password on router
  • Setting up a form of encryption
  • Media Access Control (MAC) address filtering
  • Hiding the router by stopping the router broadcasting its Service Set Identifier (SSID)
  • Turning off the router when its not in use
  • Reducing transmitter power

Encryption scrambles data si that computers with the right key can read it. Most common forms are: WEP but WPA-PSK and WPA2 are more secure. Each device has a MAC address, so you can specify which addresses can connect to your wireless network. A firewall will not stop people accessing a non-secure wireless network.

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Combining Technologies

A mobile phone and lap top would be compatible because they both have USB ports and can communicate via Wi-Fi or Bluetooth. So you could take a photo with your phone and then transfer it to the laptop using a memory stick and then transfer it using ethernet (using the ethernet port on the laptop).

Devices these days are converging (meaning they have functions that were originally performed by other devices). E.g. If your phone has an ethernet port you could take the photo and upload it using ethernet on that one device.

A device that can perform many functions is called a multifunctional device

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Bandwidth and latency

Bandwidth: measurement of capacity

The number of bits that can go through the network connection in 1 second. It is measured in bits per second (bps) - 1 Kbps (1 thousand bps) & 1 Mbps (1 million bps)

Latency: measurement of delay

Latency is the time in milliseconds between a bit leaving one device and arriving at the other. It is measured in milliseconds.

Best networks have a high bandwidth and a low latency

For streaming videos from Youtube you need a high bandwidth network connection or the video will keep pausing as your computer waits for it to arrive.

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Wi-Fi and mobile broadband

Most common ways to of connecting to the internet

Wi-Fi - devices need to be within range of a wireless access point or 'hotspot'

  • Good range - works up to 60 metres from the hotspot.
  • Speeds of up to 54 Mbps
  • Quite widely available
  • Hackers sometimes set up fake Wi-Fi hotspots putting users' details at risk
  • Cannot use if not in range of an access point

Mobile Broadband - allows devices to connect to the Internet via the same network that 3G mobile phones use

  • Far greater coverage than Wi-Fi
  • More secure than Wi-Fi - data is encrypted
  • Have to pay for mobile broadband, including roaming charges if you are abroad
  • Downloads limited
  • Lower bandwidth than Wi-Fi
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Peer-to-peer networks

Is when digital devices communicate wirelessly with each other directly without the need for a transmitter betweem them.

In the past devices communicated with each other through a transmitter: a wireless access point when using Wi-Fi and a mobile phone mast when using mobile broadband

Wi-Fi Direct - Allows devices to connect directly using Wi-Fi without the need for a wireless access point

  • Allows users to set up peer-to-peer networks
  • Allows the devices to use an access point for normal Wi-Fi use

Bluetooth - another way to establish a peer-to-peer network

  • Allows devices to communicate automatically when within range - with no user involvement
  • Can connect up to eight devices at the same time
  • Low power so does not interfere with other devices
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Communication Protocols 1

Protocols = rules that devices must follow when they are communicating with each other

VoIP - Voice over Internet Protocol

  • Set of rules for transmitting audio messages over the internet. Rules enable you to make free voice calls between computers. Useful when travelling
  • Having a webcam allows you to make video calls
  • VoIP can even be used on a smartphone

POP3, IMAP and SMTP - are all protocols used when sending and receiving emails

SMTP (Simple Mail Transfer Protocol) is used when mail is sent from the sender to the recipients email server

POP/POP3 (Post Office Protocol) means the mail sever will download the email to the computer. The email can then be deleted from the server and read offline

IMAP (Internet Message Access Protocol) means the email is read on the mail server. Can be accessed anywhere with an internet connection.

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Communication Protocols 2

HTTP (Hypertext Transfer Protocol) is the protocol of the World Wide Web

When you type in a website address the client (browser) uses HTTP to ask the web server to send the files needed to show the web page on your computer

HTTPS - when sending confidential information over the internet the web server uses a protocol called Hypertext Transfer Protocol over SSL (Secure Sockets Layer) or HTTPS. The data transferred is encrypted so that it cannot be read by anyone except the reciptent. when the HTTPS protocol is being used the URL should show: https://

How HTTPS works

  • Browser checks sites certificate
  • Web server and browser determine the encryption types they can both use to understand each other
  • Browser and web server send each other unique codes to use when encrypting information being sent
  • Browser and web server start talking to each other using the encryption
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Security Risks in a network

Remote Access - all computers visible in a network and all computers visible on the internet. Prevent remote access by using a firewall. A firewall is a software that permits or blocks connections between your computer and other computers on the network according to the settings you have set. A firewall isnt enough as some malware (viruses) shut down firewalls.

Virus - a program designed to caus other computer programs to malfunction or stop working. Viruses can replicate themselves and can be passed on to other users in files and emails.

Precautions against viruses:

  • install anti-virus software and keep it updated
  • Run regular scans of files on the computer
  • Only download from trusted websites
  • Only open emails and attachments from recognised senders
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Security risks in a network 2

Intercepting Data

Users send personal data across the internet e.g. credit card information, personal details, sensitive company information and bank account information. This can be read by other users who may use it to commit fraud. Encryption is one way to keep it safe

Illegal Access

Data can be stolen or corrupted by unauthorised users on a network.

Authentication - the process of identifying an individual - prevents illegal access

Most networks require a username and password in order to prove their identity. A strong password consists of: numbers, capital letters and punctuation.

To make sure they are human and not a computer they are given a Captcha test.

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Physical security risks

Physical access to data - physically accessing your computer and stealing it. Lock function in windows so a password is required to start use again.

Preventing theft of equipment

  • Chains and locks - fix a computer or laptop to a desk. Having locks on doors and blinds on windows.
  • Radio Frequency Identification (RFID) chips in items so they can be scanned to identify the product, can set off an alarm if the item is being taken out of a room or building

Keeping people out:

  • Burglar alarm
  • CCTV cameras inside and outside
  • Authenticate their identity
  • Swipe cards
  • Blinds so people cant see in
  • Biometrics e.g. fingerprint or iris
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