chapter 5

• Devices


  Need to connect to a network and abide by protocols
• IP address


  Identifies devices on a network, can be assigned by an administrator or DHCP, not fixed and depend on the network
• Types of IP addresses

  • IPv4 (8 numbers separated by dots, e.g. 192.168.1.1)
  • IPv6 (8 groups of hexadecimals separated by colons, e.g. 2001:0268:0000:0042:0000:8u2e:0370:7334)
• IPv6 was developed because the number of devices is growing faster than the number of physical users
• MAC address


  A universally unique identifier made up of 6 pairs of numbers/letters, specific to the network interface card (NIC)
• Uses of MAC addresses


  • Identifying devices on a network
  • Tracking devices on a network
  • Changing device's access to a network
  • Adjusting dynamic/static IP addresses
• Each time a device connects to a network, it is identified by DHCP (usually using its MAC) and given the same IP address as before
• Device names are not the best way to identify devices on a network as several devices can have the same name
• Components of wired and wireless networks

  • Cables (Cat5, Cat6, optical fibers)
  • Wireless access point (WAP)
  • Gateway
  • Router
  • Switch
  • Booster
  • Server
• Cables


  Used to connect devices in a wired network, speed measured in Mbit/s or Gbit/s
• Wireless access point (WAP)


  Connects devices with WiFi connectivity to a wired network wirelessly, built into routers and boosters
• Gateway


  Connects LAN to WAN
• Router


  Stores all the connected device's IP addresses and forwards network traffic using the fastest route
• Switch


  Has many ports to connect devices with wires
• Booster


  Amplifies a network signal to cover larger distances
• Server


  A computer that shares its resources with connected devices, called clients
• Types of servers


  • Authentication server
  • Print server
  • File server
  • Application server
  • Web server
• Authentication server


  Checks usernames and passwords when a user logs in, provides an electronic certificate to access resources
• Print server


  Manages multiple printers, deals with print requests from client computers and adds jobs to a queue
• File server


  Allows users to access shared and private storage
• Application server


  Provides clients with access to applications that can be run directly from the server
• Web server


  Processes requests for data made via HTTP, all the content stored on web servers is the World Wide Web
• Aspects needed to connect to and use the internet

  • Internet service provider
  • Web browser
  • Search engine
  • Filter software
• Internet service provider


  Grants access to telecommunications infrastructure
• Web browser


  Takes requests and guarantees access to web servers
• Search engine


  Allows users to enter keywords which are compared with web pages stored in a database to provide the most relevant results
• Filter software


  Allows administrators to control users from accessing inappropriate/risky content by filtering web pages through their URL (web address)
• Types of LAN/home networks

  • Peer-to-peer network
  • Client-server network
• Peer-to-peer network


  • Devices are connected to each other and share resources without a server
  • Shared file and storage
  • Shared peripherals
  • Easier communication
  • More flexibility
  • Better media usage
  • Shared access to the internet
• Client-server network


  • All devices are connected to one server
  • Roaming profiles - log into your account from any device
  • Administrator control over user access rights
  • Centralised administration - entire networks easily moderated and kept safe
  • Centralised backup - no hassle for individual users, backup is automated
  • Shared software
  • Shared storage and file access - file permissions can be set, amount of storage available to others
• Techniques for securing data on networks

  • Logins and passwords
  • Firewalls
  • Encryption (Caesar cipher, symmetric key, public key)
  • Wireless encryption protocols (WEP, WPA)
  • Virtual private networks (VPNs)
• Logins and passwords


  Users can only access resources with the correct login details, passwords are used to authenticate a user to a network
• Firewalls


  Found in gateways, control what enters the network or LAN
• Encryption


  The process of encoding, scrambling and jumbling data so unauthorised users can't understand it
• Caesar cipher


  All data is shifted by a certain number of units to the left, the number of units is the key
• Symmetric key encryption


  Uses the same key to encrypt and decrypt
• Public key encryption


  Uses two mathematically related keys, one public key to encrypt and one private key to decrypt
• Wireless encryption protocols


  WEP - all data sent out of a network is encrypted using the same key

  WPA - every single device has a unique key on the network, every data packet sent out is encrypted with a unique key
• Virtual private network (VPN)


  Allows you to access LANs from remote locations, used for secure payments, staying away from tracking, accessing work network from home, accessing geographically locked content