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Network Fundamentals Outline • • • • • • • LANs LAN Routers / Gateways Wireless Connection Firewalls NAT Network Protocols Protocol Analysis cs490ns - cotter 2 Single Machine • Security Risk: Physical Security – Access to Machine (loss of equipment) – Hack Machine (loss of information) cs490ns - cotter 3 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 cs490ns - cotter 4 Local Area Networks (Routers / Gateways) Internet Router / Gateway cs490ns - cotter 5 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 cs490ns - cotter 6 Wireless Connection WAP + Router cs490ns - cotter Internet 7 Firewalls • Provides a mechanism to control / monitor access to the LAN Firewall cs490ns - cotter Internet 8 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 cs490ns - cotter 9 Network Address Translation 123.75.46.89 192.168.1.1 192.168.1.25 134.193.17.52 Web Server cs490ns - cotter NAT Local User 10 Network Protocols OSI Model Internet Application Layer Presentation Layer Application Layer Session Layer Transport Layer TCP / UDP Layer Network Layer Internet Protocol Data Link Layer Physical Layer Physical Layer cs490ns - cotter 11 LAN Physical Layer Protocols • Ethernet – 10base5 – 10base2 – 10baseT, 100baseT, 1000baseT • Wireless Networks – 802.11a – 802.11b – 802.11g • Token Ring • etc. cs490ns - cotter 12 WAN Physical Layer Protocols • Telecommunications – – – – DS0, DS1, DS3 SONET ISDN etc. • Metro Area Protocols – Cellular Telephone – FDDI – WiMAX cs490ns - cotter 13 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. cs490ns - cotter 14 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 cs490ns - cotter 15 Application Support Protocols • Provide Security – SSH / SSL – HTTPS • Provide Compression / Data Translation – zip , tar, compress – MIME cs490ns - cotter 16 Application Layer Protocols • Support specific network applications – FTP – WWW (HTTP, etc.) – E-MAIL cs490ns - cotter 17 Protocol Analysis • Packet Sniffers – WireShark (Ethereal) – Etherpeek – EtherDetect – Zx Sniffer – AnalogX PacketMon – Colasoft Capsa – AirMagnet Enterprise (Wireless monitoring) – etc. cs490ns - cotter 18 Wireshark Example cs490ns - cotter 19 Summary • • • • • • • LANs LAN Routers / Gateways Wireless Connection Firewalls NAT Network Protocols Protocol Analysis cs490ns - cotter 20