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Network Fundamentals

Network Fundamentals. Outline. LANs LAN Routers / Gateways Wireless Connection Firewalls NAT Network Protocols Protocol Analysis. Single Machine. Security Risk: Physical Security Access to Machine (loss of equipment) Hack Machine (loss of information). Local Area Networks.

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Network Fundamentals

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  1. Network Fundamentals

  2. Outline • LANs • LAN Routers / Gateways • Wireless Connection • Firewalls • NAT • Network Protocols • Protocol Analysis

  3. Single Machine • Security Risk: Physical Security • Access to Machine (loss of equipment) • Hack Machine (loss of information)

  4. Local Area Networks • Security Risk: Physical Security • Access to Machine (loss of equipment) • Access to Hub / Switch (loss of information) • Hack Machine (loss of information) Hub / Switch

  5. Local Area Networks(Routers / Gateways) Internet Router / Gateway

  6. Local Area Networks(Access Technologies) • 56 Kbps Modem • Establish a point-to-point connection to ISP • Use PPTP (etc.) to establish an internet connection • Private link • DSL • Full Time, Broadband connection • Uses existing telecom facilities • Private link • Cable Modem • Full Time, Broadband connection • Shares existing cable TV facility with others

  7. Wireless Connection WAP + Router Internet

  8. Firewalls • Provides a mechanism to control / monitor access to the LAN Firewall Internet

  9. Network Address Translation • Many networks configured with private IP addresses (10.0.0.0, 172.0.0.0, 192.168.0.0) • Must convert to public address for Internet access. • May also have many hosts sharing limited network addresses. • If only 1 network address, then service is called Port Address Translation - PAT • NAT provides the translation services

  10. Network Address Translation 123.75.46.89 192.168.1.1 192.168.1.25 134.193.17.52

  11. Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer Network Protocols OSI Model Internet Application Layer TCP / UDP Layer Internet Protocol Physical Layer

  12. LAN Physical Layer Protocols • Ethernet • 10base5 • 10base2 • 10baseT, 100baseT, 1000baseT • Wireless Networks • 802.11a • 802.11b • 802.11g • Token Ring • etc.

  13. WAN Physical Layer Protocols • Telecommunications • DS0, DS1, DS3 • SONET • ISDN • etc. • Metro Area Protocols • Cellular Telephone • FDDI • WiMAX

  14. Network Layer Protocols • Internet Protocol (IP) • Routes packets across the network • Manages packet fragmentation across network • Internet Control Message Protocol (ICMP) • Provides support for IP and TCP • Address Resolution Protocol (ARP) • Provides address resolution between network layer and data link layer addresses.

  15. Transport Layer Protocols • Transmission Control Protocol (TCP) • Provides reliable end-to-end packet transport • Provides packet flow control • User Datagram Protocol (UDP) • Provides simplified end-to-end packet transport • No control overhead • No packet fragmentation

  16. Application Support Protocols • Provide Security • SSH / SSL • HTTPS • Provide Compression / Data Translation • zip , tar, compress • MIME

  17. Application Layer Protocols • Support specific network applications • FTP • WWW (HTTP, etc.) • E-MAIL

  18. Protocol Analysis • Packet Sniffers • WireShark (Ethereal) • Etherpeek • EtherDetect • Zx Sniffer • AnalogX PacketMon • Colasoft Capsa • AirMagnet Enterprise (Wireless monitoring) • etc.

  19. Wireshark Example

  20. Summary • LANs • LAN Routers / Gateways • Wireless Connection • Firewalls • NAT • Network Protocols • Protocol Analysis

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