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Network Protocols

Network Protocols. Lesson 5. Objectives. Objectives. Objectives. Objectives. Protocol Suites. Protocol: A set of agreed-on instructions designed to allow computers to communicate to each other across a network connection

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Network Protocols

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  1. Network Protocols Lesson 5

  2. Objectives

  3. Objectives

  4. Objectives

  5. Objectives

  6. Protocol Suites • Protocol: A set of agreed-on instructions designed to allow computers to communicate to each other across a network connection • Protocol suite: A group of networking protocols designed to work together to accomplish separate tasks • Protocol stack: All the protocols from a protocol suite that are currently being used

  7. TCP/IP Protocol Suite • Built around the Transmission Control Protocol and the Internet Protocol • Also includes many different protocols across all layers (of the TCP/IP Model) • Network Access layer • Internet layer • Transport layer • Application layer

  8. Network Access Layer Protocols • Ethernet • Frame Relay • Point-to-Point Protocol • IEEE 802.11 protocols • Most of the other IEEE 802 standards • UTP protocols • Many more

  9. Internet Layer Protocols • Internet Protocol version 4 (IPv4) • Internet Protocol version 6 (IPv6)

  10. Internet Protocol version 4 (IPv4) • Moves data packets from one location on a packet-switched network to another location based on the IP address of the packet being moved • IP only verifies the header of a packet and not the data in the packet • Several types of errors are possible: data corruption, lost data packets, duplicate arrivals, out-of-order packet delivery

  11. Internet Protocol version 4 (IPv4) Header

  12. Internet Protocol version 6 (IPv6) • Uses 128-bit address verses the 32-bit addresses used by IPv4 • Other advantages • Multicasting • Stateless Address Configuration (SLAAC) • Built in network security features

  13. Internet Protocol version 6 (IPv6) Header

  14. Address Resolution Protocol (ARP) • Determines the MAC address for the next hop • Adjusts the frame accordingly so that the frame can be moved to the next hop • ARP needs to work on both Layer 2 (Data Link) and Layer 3 (Network) of the OSI Model

  15. Internet Control Message Protocol (ICMP) • Used mainly by the operating system of a computer to send messages about the network • Used for network diagnostic and routing purposes • Utilities • Ping • Traceroute/tracert

  16. Internet Group Management Protocol (IGMP) • Used by: • IP hosts to manage their multicast groups’ dynamic membership • Connecting routers to find those group members

  17. Transport Layer Protocols • Primary protocols • Transmission Control Protocol (TCP) • User Datagram Protocol (UDP) • Use port addresses or ports • Well-known • Registered • Dynamic or private

  18. Transmission Control Protocol (TCP) • Provides communication services between Application layer services, protocols, and processes and the IP • Concerned with getting data from one network application such as an e-mail server or web server to another network application such as an e-mail client or web client

  19. Transmission Control Protocol (TCP) (Cont.) • Popular Application layer services that use TCP: • E-mail • World Wide Web • FTP • SSH • Peer-to-peer file sharing • Some forms of media streaming

  20. Transmission Control Protocol (TCP) (Cont.) • TCP manages: • Flow control • Network congestion • Segment size • The rate at which data is allowed to move • he number of segments permitted before an acknowledgment is required before additional data segments can be sent

  21. Transmission Control Protocol (TCP) Header

  22. User Datagram Protocol (UDP) • The connectionless counterpart of TCP • Does not guarantee reliable delivery • Is primarily used to give other protocols such as IP access to datagram services like port number

  23. User Datagram Protocol (UDP) Header

  24. Application Layer Protocols • Designed to carry out specific purposes or functions • Examples: File transfers, transferring web pages, transferring e-mails between servers, transferring e-mail from servers to clients • No Application layer protocol can do its job alone; needs lower-level protocol(s) to carry out transmission of services

  25. Bootstrap Protocol (BOOTP) • Untended to automate IP addressing across a network • Replaced byDHCP

  26. Dynamic Host Control Protocol (DHCP) • Holds a range of IP addresses to be assigned to clients • Assigns IP addresses on an as-requested basis • Can store complete IP configuration data for its clients -- subnet mask, gateway, and DNS addresses

  27. DHCP Initialization Process

  28. Domain Name System (DNS) • Converts all URLs (which we can easily remember) to IP addresses that the Internet can use • Requires: • Name servers • Authoritative name servers • Cache servers • Resolvers

  29. DNS Name Resolution Process

  30. Hypertext Transport Protocol (HTTP) • Transports Hypertext Markup Language (HTML) documents, aka web pages, over the Internet • Retrieves graphics, images, and other types of media

  31. HTTP Process • Browser or other client sets up a TCP session with a server • Sends an HTTP request to port 80 for a specific file or web page • HTTP request identifies the document or file it wants and sends a request to “get” that particular document or file • Server responds with an acknowledgment and the requested content or error message

  32. Secure Sockets Layer (SSL) • Used to secure Internet communications • Designed to carry out three basic tasks: • Server authentication • Client authentication • Encrypt TCP sessions • Is usually attached to other Application layer protocol • Example: HTTPS or HTTP Secure uses SSL

  33. Hypertext Transport Protocol Secure (HTTPS) • Combines HTTP and SSL/TLS • Allows: • Web pages to be authenticated • For the encryption of transmissions from web servers • HTTPS connections start URLs withhttps:// rather than http://

  34. File Transfer Protocol (FTP) • Sends and manipulates files over a TCP/IP network • Can use the stream, block, or compressed transmission method • Secure version of FTP is Secure FTP or SFTP • Indicated in URL bars as ftps://

  35. Voice over Internet Protocol (VoIP) • A group of technologies used to transmit voice data over packet-switched networks including but not limited to the Internet • Helps lower operational costs and is flexible • Session Initiation Protocol (SIP) used to set up VoIP sessions • Real-Time Transport Protocol (RTP) used to implement VoIP; carries streaming media such as voice or video

  36. Terminal Network (TELNET) • Provides bidirectional interactive command line access to either a remote or local host • Highly insecure

  37. Secure Shell (SSH) • Remotely connects to other hosts just like TELNET • Has some built-in security features • Uses public key encryption to authenticate onto another network device • Able to use SFTP (SSH File Transport Protocol or Secure File Transfer Protocol) or SCP (Secure Copy) to encrypt and transport data across network connections

  38. Remote Desktop Protocol (RDP) • An Application layer proprietary protocol created by Microsoft • Provides a user a graphical interface for application across a network to another computer • Provides a graphical interface for most modern operating systems including Windows, MAC OS X, Android, Linux, and UNIX. RDP uses TCP port 3389

  39. E-mail Related Protocols • Simple Mail Transport Protocol (SMTP) • Post Office Protocol (POP) • Internet Mail Access Protocol (IMAP)

  40. Network Time Protocol (NTP) • Used to synchronize clocks over packet-switched networks • Uses UDP and port 123 to carry out its synchronizations

  41. Simple Network Management Protocol (SNMP) 2/3 • Manages network systems • Requires: • Managed devices • Agents • The network management system • Very useful to administrators but poses security risk • Hackers can sniff management communications, for example

  42. How Protocols Work Together • This section uses Wireshark, a protocol analyzer, to demonstrate how protocols work together

  43. Wireshark with Captured Protocols

  44. Protocols Captured by Wireshark

  45. Packet Detail Screen by Wireshark

  46. Packet Detail Screen by Wireshark with Protocol Headers Expanded

  47. Packet Detail Screen by Wireshark with Internet Protocol Header Fully Expanded

  48. Packet Detail Screen by Wireshark Showing the Data Window Fully Expanded

  49. Routing Protocols • Routed protocols are protocols that can be routed over a network via routers and other network devices • Routing protocols are protocols used by routers to compile routing tables, which are then used to move routed protocols around the network • Compose routing tables that are then used to determine the best routes for data as they head to their specific destinations

  50. Interior Gateway Protocols versus ExteriorGateway Protocols • Interior Gateway Protocols (IGPs) are used within an Autonomous System (AS) to discover the best routes • Exterior Gateway Protocols (EGPs) are used to discover the best routes between various Autonomous Systems

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