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Chapter 01


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Chapter 01

  1. 1. Linux Networking and Security Chapter 1
  2. 2. Networking Fundamentals <ul><li>Explain the purposes and development of computer networking </li></ul><ul><li>Identify common types of networking hardware </li></ul><ul><li>Describe how networking software operates </li></ul><ul><li>Understand when popular networking protocols are used </li></ul><ul><li>Define network routing and describe the purpose of popular routing protocols </li></ul>
  3. 3. The Development of Networked Computers <ul><li>Connecting computers and related devices in a local area network (LAN) provides: </li></ul><ul><ul><li>Ability to share information instantly </li></ul></ul><ul><ul><li>Automation of data-processing tasks that involve multiple computer systems </li></ul></ul><ul><ul><li>More efficient utilization of network resources </li></ul></ul><ul><li>Trends contributing to network capability </li></ul><ul><ul><li>Network capability added to personal computers </li></ul></ul><ul><ul><li>Reduced cost of UNIX-based server computers </li></ul></ul><ul><ul><li>Explosive Internet growth and accessibility </li></ul></ul>
  4. 4. Network Types
  5. 5. Network Types
  6. 6. Network Types <ul><li>Peer-to-peer </li></ul><ul><ul><li>Computers act as both client and server on the network </li></ul></ul><ul><ul><li>There is no reliance on a centralized server to provide access to data and other resources </li></ul></ul><ul><ul><li>Compared to a centralized client-server model, peer-to-peer is decentralized, meaning any host can communicate with any other host </li></ul></ul><ul><ul><li>Linux is thought of as a peer-to-peer operating system </li></ul></ul>
  7. 7. Network Types
  8. 8. Creating a Network
  9. 9. Creating a Network
  10. 10. Creating a Network
  11. 11. Networking Technologies <ul><li>Ethernet </li></ul><ul><ul><li>Most widely used technology </li></ul></ul><ul><ul><li>Three variation of Ethernet based on transmission speed, or bandwidth </li></ul></ul><ul><li>Token-ring </li></ul><ul><ul><li>Uses a token to identify which computer on the network has the right to transmit data </li></ul></ul><ul><ul><li>Each workstation must be connected to a multistation access unit (MAU) </li></ul></ul><ul><ul><li>Not as fast as Ethernet, and may be more expensive </li></ul></ul>
  12. 12. Networking Technologies <ul><li>Fiber Distributed Data Interface (FDDI) </li></ul><ul><ul><li>Reliable, but slower and costlier than Ethernet </li></ul></ul><ul><li>Arcnet </li></ul><ul><ul><li>Reliable, but slower token-passing technology </li></ul></ul><ul><li>Asynchronous Transfer Mode (ATM) </li></ul><ul><ul><li>high-speed, very reliable and very expensive used for Internet backbones </li></ul></ul><ul><li>Wireless LAN (WLAN) </li></ul><ul><ul><li>No cables used to connect nodes to the network </li></ul></ul><ul><ul><li>Data is transmitted via radio signals of infrared </li></ul></ul>
  13. 13. Networking Technologies
  14. 14. Networking Technologies
  15. 15. Cabling a Network
  16. 16. Cabling a Network <ul><li>Unshielded Twisted Pair (UTP) </li></ul><ul><ul><li>made of several pairs of wires encased in plastic </li></ul></ul><ul><ul><li>Comes in six categories, with CAT 6 being the highest quality and speed </li></ul></ul><ul><ul><li>UTP is relatively inexpensive, but is susceptible to interference from other electrical signals </li></ul></ul><ul><li>Shielded Twisted Pair (STP) </li></ul><ul><ul><li>Similar to UTP, but includes a metallic shielding around each pair of wires </li></ul></ul><ul><ul><li>Shielding protects from electrical interference, but is more expensive than equivalent quality UTP </li></ul></ul>
  17. 17. Cabling a Network <ul><li>Fiber-optic </li></ul><ul><ul><li>A specialized solution using light pulses rather than electrical pulses to transmit data </li></ul></ul><ul><ul><li>Extremely fast transmission speeds and is immune to electrical interference </li></ul></ul><ul><ul><li>Most secure system, but most expensive too </li></ul></ul><ul><li>Coaxial Cable (coax) </li></ul><ul><ul><li>Was popular, but overtaken by UTP </li></ul></ul><ul><ul><li>Used for cable modems </li></ul></ul>
  18. 18. Choosing Cable <ul><li>Choosing transmission media (cable) means making trade-offs between: </li></ul><ul><ul><li>Cost of physical cable and its installation </li></ul></ul><ul><ul><li>Maximum and typical speed </li></ul></ul><ul><ul><li>Susceptibility to interference </li></ul></ul><ul><ul><li>Expanding the network over time (scalability) </li></ul></ul><ul><li>If a legacy system (existing wiring) is present: </li></ul><ul><ul><li>Consider utilization of any existing cable and its ability to handle present and future network traffic </li></ul></ul><ul><ul><li>Consider usage by intended network workstations </li></ul></ul>
  19. 19. Last Mile Options
  20. 20. How Data is Transferred on a Network <ul><li>Data is transferred across a network as a series of electronic or light pulses </li></ul><ul><ul><li>These on/off pulses are interpreted as data, bits and bytes which are organized into packets </li></ul></ul><ul><li>A packet refers to a collection of data with identifying information for network travel </li></ul><ul><ul><li>Packets are different sizes based on the network type being used and are no larger than the Maximum Transfer Unit (MTU) of the network </li></ul></ul><ul><ul><li>If more than the MTU must be send, additional packets are used </li></ul></ul>
  21. 21. How Data is Transferred on a Network <ul><li>Each packet is organized into two parts: </li></ul><ul><ul><li>The payload is the data to be transferred </li></ul></ul><ul><ul><li>The header defines how the parts of the network should handle the data </li></ul></ul><ul><li>Ethernet transmits data packages using a system called contention </li></ul><ul><li>Throughput refers to how much payload information can be transmitted on a network </li></ul>
  22. 22. Network Topologies
  23. 23. Network Topologies
  24. 24. Network Topologies
  25. 25. Network Topologies
  26. 26. Connecting Multiple Networks
  27. 27. Networking Software <ul><li>A network-capable operating system is required in order to use networking hardware </li></ul><ul><li>In networking, different tools are required for different tasks </li></ul><ul><li>Networking is built on a host of networking tools and mist of these tools are protocols </li></ul><ul><li>A protocol is a formalized set of rules for communication </li></ul>
  28. 28. Conceptual Models of Networking
  29. 29. Conceptual Models of Networking
  30. 30. Conceptual Models of Networking <ul><li>The software used to maintain each protocol is often called a protocol stack </li></ul><ul><li>Transport layer protocols can be: </li></ul><ul><ul><li>Connectionless, or stateless, which sends each packet without regard to whether any other packet was received by the destination computer </li></ul></ul><ul><ul><li>Connection oriented, or stateful, which maintains information about which packets have been correctly received by the destination computer </li></ul></ul>
  31. 31. The Internet Protocol
  32. 32. The Internet Protocol
  33. 33. IP Addressing <ul><li>IP works by assigning a unique address to every computer on the Internet </li></ul><ul><li>IP Addressing is a scheme that allows each network device to have a unique ID number </li></ul><ul><ul><li>An IP address is assigned to each computer network card or network device </li></ul></ul><ul><ul><li>Each address is 32 bits long, made up of four 8-bit numbers separated by periods (dotted-quad) </li></ul></ul><ul><ul><li>Addresses have two parts: a network ID and a host ID </li></ul></ul>
  34. 34. IP Addressing
  35. 35. IP Addressing
  36. 36. Broadcast and Multicast Addressing <ul><li>To transmit data to every device on the network, use the broadcast address </li></ul><ul><ul><li>A special IP address where the host ID is all 1’s </li></ul></ul><ul><ul><li>These types of messages are used chiefly for system administration purposes </li></ul></ul><ul><li>To transmit data to multiple specific hosts, use multicasting </li></ul><ul><ul><li>Used when data needs to go to a subset of the devices on the network </li></ul></ul><ul><ul><li>True mulitcasting is not supported by the Internet yet, but its use is expected to increase </li></ul></ul>
  37. 37. IPv6 <ul><li>Replacement to current IP version (IPv4) which is rapidly running out of addresses </li></ul><ul><li>IPv6 uses 128 bits per IP address </li></ul><ul><li>IPv6 includes these enhancements over IPv4: </li></ul><ul><ul><li>Will make multicasting more workable </li></ul></ul><ul><ul><li>Allows dynamic configuration of networks </li></ul></ul><ul><ul><li>Allows routers to make more intelligent routing decisions </li></ul></ul><ul><li>IPv6 requires more sophistication in the infrastructure components of the Internet </li></ul>
  38. 38. Transport Protocols
  39. 39. Name Services <ul><li>Are Application-layer software programs that let a computer provides names in place of IP addresses, also called name resolution. </li></ul><ul><li>A domain name refers to a collection of computers , usually on the same network, that can be accessed using a common name </li></ul><ul><li>The name service used by the Internet is Domain Name Service (DNS) </li></ul>
  40. 40. Transmission Control Protocol <ul><li>The workhorse of the Internet, in that all of the services utilized rely on TCP as their transport protocol </li></ul><ul><ul><li>These include HTTP, SNTP, FTP and Telnet </li></ul></ul><ul><li>TCP is connection oriented and therefore guarantees delivery of each data packet </li></ul><ul><li>TCP provides application transport services using ports, which are numbers that are associated with network-capable applications </li></ul>
  41. 41. Transmission Control Protocol
  42. 42. User Datagram Protocol <ul><li>UDP provides fast, connectionless service </li></ul><ul><li>Provides a similar service to IP, but with addition of port numbers </li></ul><ul><li>Applications that use UDP include name servers and network management utilities </li></ul><ul><li>The UDP header includes four fields: </li></ul><ul><ul><li>Source and destination ports </li></ul></ul><ul><ul><li>Message length and checksum </li></ul></ul>
  43. 43. Application Protocols
  44. 44. Routing Concepts
  45. 45. Routing Concepts
  46. 46. Routing Concepts <ul><li>Routers use a routing table and a routing algorithm to decide where to send packets </li></ul><ul><li>Routing tables consist of at least three items: </li></ul><ul><ul><li>Network ID for which a route is being stored </li></ul></ul><ul><ul><li>The network interface through which the network ID can be reached </li></ul></ul><ul><ul><li>The IP address of the upstream router that handles the listed network ID </li></ul></ul><ul><li>Routing tables may contain: </li></ul><ul><ul><li>Routing algorithm, or engine, that determines how to process a packet sent to the router </li></ul></ul>
  47. 47. Chapter Summary <ul><li>Networks allow users to work more efficiently </li></ul><ul><li>Client-server technology assumes intelligent systems </li></ul><ul><li>Networking hardware sends data over transmission media, where data collections are called a packets </li></ul><ul><li>Network topologies (bus, star, ring) define the physical and logical layout of a network </li></ul><ul><li>Many types of transmission media are available </li></ul><ul><li>Modern networks use different layers of software to handle the different aspects of managing a network </li></ul><ul><li>The OSI and Internet models are two important conceptual layered models of networking </li></ul>
  48. 48. Chapter Summary <ul><li>Networking protocols can be connection oriented (guaranteed data delivery) or connectionless </li></ul><ul><li>IP addressing can be defined with or without using classes, but always consist of network and host IDs </li></ul><ul><li>Fragmentation allows packets with different MTU sizes to be routed across intermediate networks </li></ul><ul><li>IPv6 will provide more addresses and many additional features (over IPv4) as it is rolled out </li></ul><ul><li>Broadcasting and multicasting provide special methods of sending IP packages to multiple hosts simultaneously </li></ul>
  49. 49. Chapter Summary <ul><li>Name services convert between IP addresses and human-readable domain names </li></ul><ul><li>TCP, UDP and ICMP are Transport-layer protocols </li></ul><ul><li>Many application protocols are used as part of network-aware programs such as Web servers and email servers </li></ul><ul><li>Routers move packets between network segments and they maintain a routing table to identify how to reach various network IDs </li></ul>