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Chapter 01 Chapter 01 Presentation Transcript

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