week 2

• Protocol


  Network protocols allow communication between different network-enabled devices, for example, laptops, tablets, smartphones, desktops, servers, and other network-enabled devices

  
• A human protocol and a computer network protocol

  • Hi
  • Got the time?
  • 2:00
  • TCP connection request
  • TCP connection response
  • GET http://www.uwl.ac.uk/example.pdf
  • <file>

  
• Communication protocols


  • Connection-oriented
  • Connectionless

  
• Connection-oriented


  Establishes a dedicated connection between the devices in a network before transmitting data, and this connection is maintained throughout the communication and is terminated once the communication is over

  
• Connectionless


  Doesn't establish a dedicated connection between devices before transmitting data. A connectionless protocol sends each packet as an independent unit and transmits them separately

  
• Protocol categories


  • Network Communication protocols
  • Network Security protocols
  • Network Management protocols

  
• Network Communication protocols


  • HTTP, FTP, POP3, SMTP, IMAP
  • Internet Protocol
  • User Datagram Protocol
  • Transmission Control Protocol

  
• Transmission Control Protocol


  TCP chunks up data into data packets that can be sent securely and quickly while minimizing the chance of data loss. It provides a stable and reliable mechanism

  
• Internet Protocol


  IP is responsible for the addressing of a data packet. IP encapsulates the data packet to be delivered and adds an address header. The header contains information on the sender and recipient IP addresses. This protocol isn't concerned about the order in which the packets are sent or received. It also doesn't guarantee that a packet will be delivered, only the address

  
• TCP/IP


  Provides an overarching framework for communication on the internet (currently)

  
• User Datagram Protocol


  UDP is a connectionless protocol that offers a low-latency implementation. For real-time services like computer gaming, voice or video communication, live conferences; we need UDP. Since high performance is needed, UDP permits packets to be dropped instead of processing delayed packets. There is no error checking in UDP, so it also saves bandwidth. UDP is more efficient in terms of both latency and bandwidth
• Hypertext Transfer Protocol


  The HTTP protocol uses TCP/IP to deliver web page content from a server to your browser. HTTP can also handle the download and upload of files from remote servers
• File Transfer Protocol


  FTP is used to transfer files between different computers on a network. Typically, FTP is used to upload files to a server from a remote location. While you can use FTP to download files, web-based downloads are typically handled through HTTP
• Email Protocol


  • Post Office Protocol 3 (POP3)
  • Simple Mail Transfer Protocol (SMTP)
  • Interactive Mail Access Protocol (IMAP)
• Post Office Protocol 3 (POP3)


  POP3 is one of three email protocols. It's most commonly used by an email client to allow you to receive emails. This protocol uses TCP for the management and delivery of an email
• Simple Mail Transfer Protocol (SMTP)


  SMTP is another one of the three email protocols. It's most commonly used to send emails from an email client via an email server. This protocol uses the TCP for management and transmission of the email
• Interactive Mail Access Protocol (IMAP)


  IMAP is the more powerful of the three email protocols. With IMAP and an email client, you can manage a single mailbox on an email server in your organization
• Network Security protocols


  • Hypertext Transfer Protocol Secure (HTTPS), Kerberos
  • Transport Layer Security (TLS)
  • Secure Socket Layer (SSL)
  • Secure Shell (SSH)
• Secure Socket Layer (SSL)


  SSL is a standard encryption and security protocol. It provides a secure and encrypted connection between your computer and the target server or device that you accessed over the internet. It works by encrypting communication, ensuring that data exchanged between the two parties remains confidential and tamper-proof. SSL uses public-key cryptography and digital certificates to authenticate servers and encrypt data. While initially the standard, it has been largely replaced by its successor, TLS (Transport Layer Security)
• Transport Layer Security (TLS)


  TLS is the successor to SSL and provides a stronger and more robust security encryption protocol. It's designed to stop message forgery and tampering and eavesdropping. It's typically used to protect web browser communications, email, VoIP, and instant messaging. While TLS is now used, the replacement security protocol is often still called SSL
• Hypertext Transfer Protocol Secure (HTTPS)


  HTTPS is a combination of the standard HTTP protocol (used for transferring web pages) and the secure SSL/TLS protocol. It essentially adds a layer of security to HTTP communication, making it ideal for transmitting sensitive data like passwords, credit card information, and personal details. When you see a website address with "https://" at the beginning, it means the connection is secured with SSL/TLS
• Secure Shell (SSH)


  SSH is a cryptographic network security protocol that provides a secure data connection across a network. For secure remote access, file transfer, or creating secure tunnels, use SSH
• Kerberos


  It provides a robust authentication for client-server-based applications through secret-key cryptography. Kerberos assumes that all endpoints in the network are insecure
• Network Security protocols- summary

  • SSL/TLS
  • HTTPS
  • SSH
  • Kerberos
• Simple Network Management Protocol (SNMP)


  SNMP is an internet protocol that allows for the collection of data from devices on your network and the management of those devices. The device has to support SNMP to gather information. Devices that typically support SNMP include switches, routers, servers, laptops, desktops, and printers

  
• Internet Control Message Protocol (ICMP)


  ICMP is one of the protocols included within the Internet Protocol suite (IPS). It allows network-connected devices to send warning and error messages, along with operation information about the success or failure of a connection request, or if a service is unavailable. Unlike other network transport protocols like UDP and TCP, ICMP isn't used to send or receive data from devices on the network

  
• Network protocols are typically created according to industry standard by various networking or information technology organizations
• Main groups that create network protocols

  • The Institute of Electrical and Electronics Engineers (IEEE)
  • The Internet Engineering Task Force (IETF)
  • The International Organization for Standardization (ISO)
  • The International Telecommunications Union (ITU)
  • The World Wide Web Consortium (W3C)

  
• Need For Protocol Architecture

  Task of communication broken up into modules (layers) for example file transfer could use three modules: File transfer application, Communication service module, Network access module

  
• A Three Layer Model

  • Network Access Layer
  • Transport Layer
  • Application Layer

  
• Network Access Layer


  Exchange of data between the computer and the network. Sending computer provides address of destination

  
• Transport Layer


  Reliable data exchange. Independent of network being used. Independent of application

  
• Application Layer


  Support for different user applications e.g. e-mail, file transfer
• Protocol Data Units (PDU): At each layer, protocols are used to communicate. Control information is added to user data at each layer. Transport layer may fragment user data. Each fragment has a transport header added. This gives a transport protocol data unit

  
• Standardized Protocol Architecture is required for devices to communicate. Vendors have more marketable products. Customers can insist on standards based equipment. Two standards: OSI (Open System Interconnections) Reference model and TCP/IP protocol

  
• OSI Reference Model


  OSI = Open Systems Interconnection: deals with open systems, i.e. systems open for communications with other systems. Specified in ISO 7498. Model has 7 layers: Application, Presentation, Session, Transport, Network, Data Link, Physical

  
• TCP/IP Protocol


  Developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET). Used by the global Internet. Layers: Application, Host to host or transport, Internet, Network access, Physical

  
• User Datagram Protocol (UDP) is an alternative to TCP/IP. It is a communication protocol used across the Internet for especially time-sensitive transmissions such as video. It has no guaranteed delivery, no preservation of sequence, no protection against duplication, and minimum overhead