IT

• Network protocols designed to increase security and privacy of data

  • Tunnelling
  • Secure sockets layer (SSL)
  • Transport layer security (TLS)
  • Internet protocol security (IPsec)
• Tunnelling


  A communications protocol that allows for the secure transmission of data from one network to another. It allows private data packets to be sent across a public network through a method called encapsulation.
• Secure sockets layer (SSL)


  A network protocol designed to ensure connections made between web clients, such as user devices, and web/mail servers are secure. It uses both public and private keys to encrypt data that is transmitted over the secure connection.
• Transport layer security (TLS)


  Updated version of SSL
• Internet protocol security (IPsec)

  A network protocol designed to encrypt and authenticate data packets that are sent across the internet. IPSec is also part of the tunneling VPN process.
• More network protocols


  • Internet control message protocol (ICMP)
  • Address resolution protocol (ARP)
  • Inverse address resolution protocol (InARP)
  • Dynamic host configuration protocol (DHCP)
  • Hypertext transfer protocol
  • File transfer protocol
• Internet control message protocol (ICMP)


  An error reporting protocol used to generate error messages, to transmit to the sender, when network problems cause delivery problems with data packets.
• Address resolution protocol (ARP)

  A protocol responsible for translation of an IP address into a MAC address for a device. It is necessary for use between the network layer and the data link layer of the OSI model.
• Inverse address resolution protocol (InARP)


  Performs the protocols of ARP, translating a MAC address into an IP address.
• Dynamic host configuration protocol (DHCP)


  A network management protocol used to assign IP addresses to devices on a network. It manages the assignment of the address so that the administrator doesn't do it manually.
• Hypertext transfer protocol


  Used for transferring the content of web pages across the internet, from a web server to a browser.
• File transfer protocol


  Responsible for the transfer of files between a client and a server in a network.
• More protocols


  • Simple mail transfer protocol (SMTP)
  • Post office protocol (POP)
  • Internet message access protocol (IMAP)
  • Telnet
  • Secure shell
• Simple mail transfer protocol (SMTP)


  Used to send an email from a computer to a mail server, between different mail servers.
• Post office protocol (POP)

  Used to retrieve emails from a mail server. When the user checks their inbox the mail is sent from the server to their device and the protocol then deletes the email from the server.
• Internet message access protocol (IMAP)

  Same as POP but the email is not deleted from the server by the protocol, the user chooses to delete it.
• Telnet


  A protocol that allows a user to connect remotely to another computer using the internet.
• Secure shell


  Provides a secure way to access a computer over an unsecure network. It is done using strong authentication and encryption methods for communication.
• BitTorrent


  A communications protocol often used in peer to peer file sharing. It allows for the transmission of large files such as videos by distributing the load of downloading the file across several sources on the network. The several sources are collated to create a swarm, with each host given pieces of the file. This protocol allows the user to join the swarm and download the file from the available hosts simultaneously. The protocol can rearrange the pieces to create a complete file, with each piece protected so that it isn't modified.
• Peer


  A computer of equal importance or the same level of responsibility in a peer-to-peer network
• Peer-to-peer network


  1. Can be as simple as two computers in a home

  2. Can be as extensive as hundreds of peer computers connected using the internet

  3. Main reason is to share data
• Peer-to-peer network


  • Has a decentralised structure meaning there is no central point of control
  • Each user stores data on their computer they can choose to make it public or private
  • If a peer computer has a peripheral such as a printer is can make it public so that other computers can use it
• Client


  A computer in a network that is not a central point of control
• Server


  A computer in a network that is a point of control
• Client-server network


  • Contains two types of computers, a client and a server
  • The servers are a central point of control and provide a dedicated function for the network
  • All other computers in the network are called clients
  • The client is connected to the server to allow it to perform its dedicated function
  • Most networks operate using a request-responsible method
• Server types


  • File server
  • Web server
  • Mail server
  • Application server
  • Print server
  • FTP server
  • Proxy server
  • Virtual server
• File server


  Stores and manages data files. This saves the need for extensive storage space on client computers. They allow a user to use any client computer in the network and still be able to access their files and any publicly shared files available. They also allow a central backup of all data to be made
• Web server


  Stores, processes and transmits web pages
• Mail server


  Sends and receives emails. It stores incoming emails for the user that can be downloaded when requested. It forwards outgoing messages to the correct destination. Most mail servers have security checking software that will scan for malware and viruses
• Application server


  Installs and runs software applications. They provide a platform to run both desktop and web applications
• Print server


  Receives print jobs from client computers and sends them to the correct printer. This allows many client computers in a network to use the range of printers available. They can be set to print to a specific printer. They can also be set to find the next available printer or the closest to the client. If many jobs are sent to the print server at a time it will queue the jobs until it can deliver them to a printer
• FTP server


  Manages the transfer of data that uses the file transfer protocol (FTP). It keeps a log of all activity involving FTP. It uses a lot in the transfer of files over the internet
• Proxy server


  Acts as an intermediary between clients and other servers by receiving client requests and forwarding them on to the relevant server. It provides an added level of security in a network, protecting clients directly accessing resources on another server. For this reason, it can also be set to act as a firewall
• Virtual server


  Shares the hardware of another server. Created using virtualization software on another server. Multiple virtual servers could be created on one physical server. A virtual server can be given the capabilities of any of the above physical servers. Businesses sometimes use third party virtual servers that will act as a web server. This allows hosting company the ability to host several businesses websites on the hardware of a single physical server
• Spreading the functionality of the network across several servers can help a network run more efficiently
• Servers are very expensive due to high storage and performance power
• Some businesses want to have fewer physical servers and more virtual servers
• Servers can be grouped to provide functionality that would go beyond a single computer
• As a collective, servers have a huge amount of processing power that needs a large amount of power to keep cool
• A collective of servers is called a server farm, google has one with over 10,000 servers