networks and security

• • A network is two or more computers (or other electronic devices) that are connected together for the purpose of communication. They are connected by a wired medium such as cables, or by a wireless medium such as Wi-Fi.
  • A computer or device that is not connected to a network is called a stand-alone.
• Advantages of using networks

  • file sharing
  • hardware sharing - eg printer
  • communication - email, chat, or by video
  • roaming access - users can sign in to any computer + access their files

  Larger networks:

  • centralised maintenance + updates - network managers can apply software, malware and operating system updates instead of user
  • centralised security - anti-virus software and firewalls can be implemented across a network
  • user monitoring - network managers can monitor what users do
  • levels of access - Different access rights. Network managers can restrict user access to certain files
• Disadvantages of networks

  • cost - additional equipment for communication
  • management - require management by technical staff eg network manager
  • spread of malware - viruses and other forms of malware can easily spread across an improperly secured network
  • hacking - once a device is connected to another device, it is possible that data may be accessed without the device owner's permission
• A local area network (LAN) is usually found within a small geographic area such as a building or campus. A LAN has the following characteristics:

  • computers are within a small geographic area

  • computer workstations with network interface controllers (NICs), including wireless NICs

  • connected using its own dedicated cables (or wireless devices) owned by the company, organisation, or home

  • often has shared peripherals, e.g. printers
• fill in the blanks

  A) switch

  B) network interface controller

  C) wireless access point

  D) cable

  E) router

  F) communication

  G) port

  H) when traffic received, forwards to intended recipient

  I) network socket

  J) cable

  K) network socket

  L) port

  M) uses a radio transceiver

  N) sends wireless traffic into main wired network

  O) wireless

  P) Wi-Fi

  Q) switch

  R) cable

  S) twisted copper wiring or fibre-optic cable

  T) LAN

  U) WAN

  V) Internet

  
• • Routers are used to send data signals across the internet. Routers work by collecting knowledge of available routes to transmit data. They then determine the most suitable route for sending data. They allow users to connect to the Internet
• server

  • shared access to files

  • security (e.g. logging on)

  • providing access to software

  • managing print jobs

  • providing mailboxes for email

  • performing automated backups
• label

  A) faster

  B) transfer

  C) interference

  D) unauthorised

  E) access

  F) expensive

  G) one

  H) cable

  I) connections

  J) disrupting

  K) move around

  L) radio signals

  M) range

  N) interference

  O) users

  P) intercepted

  Q) unauthorised

  
• A WAN is a network that connects multiple LANs together over a wide geographical area with third party cables.

  • computers are not close together
  • external communications equipment such as a telephone line, leased line, satellite or 4G/5G are used as connections
  • a router or other physical device is needed to connect to the WAN.
• network disadvantages

  • networked computers provide more points of entry to a computer system meaning that there is an increased risk of hacking, viruses and spyware
  • viruses can spread throughout a network
  • if network resources such as servers, switches or cables fail, then it means that no users can access their data or applications until that resource has been repaired
  • users have to walk to another area within an office to collect printouts which can lead to breaches of confidentiality if somebody else picks up a printout
• • Client-server networks separate computers into servers + clients (capitalism)
  • A server is a computer that manages + stores files/provides services to clients. They control the network + allow other computers to share + communicate. Typical servers include file, applications, web, print, mail servers.
  • A client is a computer that relies on other computers (servers) to provide and manage data.
  • Clients do not usually store data.
  • Best for organisations with many computers, or to situations where many computers need access to the same information. Many schools use this type of model.
• Peer-to-peer networks (communism)

  • All computers have equal status - no computer has control over the network. No servers or clients. Instead, each computer is known as a peer. Peers store their own files, which can be accessed by other peers on the network. Therefore, a peer is both a client and a server.
  • Best suited to smaller organisations that have fewer computers, or where fewer computers need access to the same data.
• label

  A) backups

  B) centrally

  C) own

  D) anti-virus

  E) centrally

  F) software

  G) installed

  H) regularly

  I) security

  J) centrally

  K) each

  L) software

  M) deployed

  N) manager

  O) installed

  P) individually

  Q) hardware

  R) processing

  S) power

  T) hard disks

  U) memory

  V) expensive

  W) independently

  X) resilience

  Y) fails

  Z) access

  [) resources

  \) shared

  ]) management

  ^) network manager

  _) complicated structure

  `) competent

  
• Reasons for using fibre optic cable instead of copper cable include:

  • they do not suffer from electromagnetic interference like copper cable does

  • data can travel much longer distances than copper cable

  • data travels close to the speed of light which is much faster than copper cable

  • higher bandwidths (amount of data that can be transferred per second) can be achieved

  Reasons for using copper cable instead of fibre optic cable include:

  • it is cheaper per metre than fibre-optic cable

  • it already exists within telephone networks
• Most public Wi-Fi hotspots are unencrypted which means that the data that passes through the wireless network can be read by anybody with the right software connected to the same wireless network. Solutions: Find an encrypted access point which requires an encryption key or use VPN
• Bluetooth is a form of wireless communication that enables different devices to connect. It works like a small private network (PAN) between two devices, allowing them to share data and documents.

  Many modern devices incorporate Bluetooth. It is often used to connect wireless devices such as:

  • a keyboard or a mouse to a computer
  • a speaker to a smartphone
  • a smartphone to a car's multimedia system

  Bluetooth provides a simple way of connecting devices. However, it is limited in transmission speed and range and can only connect one device to another at a time
• Performance of networks

  • the number of devices on the network
  • the bandwidth of the transmission medium (a measure of the amount of data that the medium can transfer over a given period of time). Obstacles such as walls + ceilings can reduce strength of wireless signal = less bandwidth available the further away a device is from a WAP.
  • the type of network traffic
  • network latency (time difference between receiving a data packet and when it was sent)
  • the number of transmission errors