tech

• Internet


  A massive global network of interconnected computers and devices
• World Wide Web


  A way of accessing information using the internet
• The World Wide Web consists of a massive collection of web pages, and is based on the hypertext transfer protocol
• URL

  Composed of three parts: file name, protocol, web server name
• HTML

  Markup language used to structure and present web pages
• HTML


  • Has a head and body
  • Separates structure and presentation
• HTTP

  Hypertext transfer protocol, a set of rules for transferring files across the internet
• HTTPS


  Hypertext transfer protocol secure, a more secure way of sending and receiving data across a network
• How to tell a website is using SSL


  • Protocol ends in s (https)
  • Padlock on some browsers
  • Colour of address bar changes
• Browsers


  • Interpret and display HTML
  • Provide functions like bookmarks and history
  • Have forward, back and home buttons
  • Store cookies and cached pages
  • Handle CSS and Javascript
• Retrieval of web pages

  1. Request: Web browser used, URL entered, HTTP protocol used, URL sent to DNS, DNS returns IP, Request made to webserver, Webserver returns HTML

  2. Sent: URL contains domain name, Domain name used to locate IP address, DNS server stores index of IP address and domain names, Web browser sends request to web server

  3. Received: Data stored on webserver, Web server sends data to browser, Browser translates HTML
• DNS

  Domain Name Server, a system for finding IP addresses for a domain name given in a URL
• DNS

  • Eliminates the need for users to memorise IP addresses
  • Involves converting a URL into an IP address
  • Involves more than one server
• Cookies

  Messages given to browser by webserver, stored in a text file, sent back to server each time the page is requested
• Uses of cookies


  • Enable logon information to be kept
  • Provide customized pages for the user
  • Enable target adverts
  • Enable one-click purchasing with shopping carts
  • Be able to distinguish between new and repeat visitors
• Session cookies

  Stored in temporary memory, don't collect information, cease to exist when browser is closed or session is terminated
• Persistent cookies

  Stored on hard drive, remember login details, remain even after browser is closed or session is terminated
• Digital currency

  Exists purely in digital format, can be transferred between accounts
• Cryptocurrency

  Uses cryptography to track transactions, has no state control, transactions are publicly available and monitored
• Blockchain


  A decentralised database where all transactions are stored on networked computers
• Blockchain


  • New transactions create new blocks with unique hash values
  • Tampering is prevented by proof-of-work and miners
  • Whole blockchain must be attacked to hack it
  • New users get a copy of the entire blockchain
• Cyber security threats


  Brute force attacks, data interception, DDoS attacks, hacking, malware
• Brute force attacks


  • Systematically try all possible password combinations
• Data interception


  • Tapping into wired or wireless communication links using packet sniffers and wardriving
• DDoS attacks


  • Flood the network with useless spam traffic from many different computers
• Hacking


  Gaining illegal access to computer systems without permission
• Reasons for hacking


  • Curiosity, malicious reasons, financial gain, hacktivision, military
• Malware


  Programs or code that replicate with the intention of deleting, corrupting or causing computer malfunctions
• Viruses


  Malware that replicate to delete, corrupt or cause computer malfunctions
• Worms


  Standalone malware that can self-replicate to spread and corrupt whole networks
• DDoS attack

  Designed to flood a server with useless traffic, causing the server to come to a stop trying to deal with the traffic, preventing users gaining access to the web server
• In a distributed denial of service (DDoS) the spam traffic originates from many different computers, which makes it hard to block the attack
• Hacking


  The act of gaining illegal access to a computer system without the user's permission
• Hacking prevention


  • Use of firewalls, user names and frequently changed strong passwords
• Reasons for hacking


  • Curiosity (fun)
  • Malicious reasons (viruses etc.)
  • Financial gain (e.g. randsomeware)
  • Hacktivision
  • Military
• Malware


  Programs or program code that replicate (copies themselves) with the intention of deleting or corrupting files, or causing a computer to malfunction
• Viruses


  Programs or program code that replicate (copies themselves) with the intention of deleting or corrupting files, or causing a computer to malfunction
• Worms


  A type of stand-alone malware that can self-replicate, with the intention of spreading to other computers and corrupting whole networks; unlike viruses, they don't need an active host program to be opened in order to do any damage
• Trojan horse

  A program which is often disguised as legitimate software but with malicious instructions embedded within it, needing to be executed by the end-user
• Spyware

  Software that gathers information by monitoring a user's activities carried out on their computer, and sends the gathered information back to the cybercriminal