LectureWhat is a Network?1: Physical ConnectionProtocol - Definition2. Networking Protocols/Software2. Networking Protocols (cont.)Protocols you use everyday3. Networking Devices3. Networking Devices (cont.)Networking MatrixSpeed Chart – Pros/ConsTypes of Networks:Peer to Peer NetworkPeer-to-Peer Networks – Cont.Client / Server Network LAN Local Area NetworkClient Server NetworksThe Internet – WAN Wide Area NetworkInternet History -- WANFirst Internet: 1969Slide 20Internet History (cont)Internet EvolutionA Look at PacificNetUnderstanding PortsPort Scanning & Malicious ProbesLectureNetworkingWhat is a Network?•Two or More Devices Exchanging Information•Networks Require:1. A physical connection (medium)2. A language – software (protocol)3. Devices to facilitate1: Physical Connection•Telephone / Network Lines–Cat-3, Cat-5, Cat-5e, Cat-6–T1•Cables–Fiber Optic–Coaxial•Wireless (air)(a physical connection is also called a “medium”)Protocol - Definition•When computers communicate with each other, there needs to be a common set of rules and instructions that each computer follows.•An agreed-upon format for transmitting data between two devices.•A specific set of communication rules is called a protocol.2. Networking Protocols/Software•PPP (Point-to-Point Protocol)–dial-up connections•Ethernet –used for local area networks (LANs)•802.11 b/g/n/ac–short/long range wireless – 30 ft•Bluetooth–personal-range wireless•Wi-Max – “Xohm” (Sprint/Nextel, Intel, Comcast, Time Warner) 802.16–Enables usage across greater distances – up to 31 mi –30 – 40 Mbps–Distance vs. Speed2. Networking Protocols (cont.)•TCP/IP (Part of O/S)–Layered or suite of protocols for all commercial and private networks–“TCP/IP is the glue thatholds the Internet andweb together”…(TCP/IP for Dummies)Protocols you use everyday•Protocols within TCP/IP:–DNS – Resolves www address to IP address (Domain Name system)–FTP – Homework 4 – File Transfers (File Transfer Protocol)–HTTP – Rules for all web-pages (Hypertext Transfer Protocol)–IMAP – Rules for E-Mail (Internet mail access protocol)–IRC –Internet Relay Chat – AIM, MySpace–POP3 – Incoming Email (Post Office Protocol)–SMTP – Outgoing email (Simple Mail Transfer Protocol)–Telnet –Contacting computers remotely–BitTorrent P2P sharing, Limewire, KaazaList of Protocols3. Networking Devices•Hubs and Switches•Routers•Modems•Radios (Wireless)•NICs (Network Interface Card)•NIU (Network Interface Unit)3. Networking Devices (cont.)•Hub: This is the cheapest way to connect computers on a network. It's basically a box with several ports on it, one for each computer on the network. The hub helps transfer information from one computer to the other over the networking cables. •Switch: A switch is basically a better, faster version of a hub. •Router: The best way to connect your computers, especially if you plan to add a high-speed modem to the network, is with a router. The router not only connects the computers but also helps wisely manage them. It also helps put up a firewall between your computer network and the Internet.Networking MatrixNetwork Medium Protocol DeviceDial-UpTelephone LineV.90Analog ModemDSLSplit Signal Telephone LinePPPoE DSL ModemLANCat-5 Cable Ethernet NICWirelessAir 802.11/x RadioCableCoaxial Cable Ethernet Cable ModemCellularAir CDMA RadioSpeed Chart – Pros/ConsDial Up2400 bps – 56KbpsCheap – SlowCable512 KBps – 100 MbpsMust have existing cableShared bandwidthDSL129 Kbps – 8 MbpsDedicated bandwidth, not sharedWireless54 Mbps +Can be used for high speed data such as broadcast TVSatellite6 Mbps + High setup feesFiber15 Mbps – 500 MbpsGood for high bandwidth demands - MultitaskingT-3 ( 28/T-1’s $3k/monthly)44.736 MbpsLarge businesses and ISP (static IP)Types of Networks:•PAN – Personal Area Network•Peer to Peer*•LAN – Local Area Network*•CAN – Campus Area Network•MAN – Metropolitan Area Network•WAN – Wide Area Network*Peer to Peer Network•All members have equal rights•Each member authenticates users•Typical of home or small offices•Inexpensive and easy to set up•Also called a “Workgroup”Peer-to-Peer Networks – Cont.In a peer-to-peer system there are no fixed clients and servers.Client / Server Network LANLocal Area Network•Server(s) for special applications–Printing–File Sharing•Single login authentication•Typical of campus or enterprise networks•Expensive servers and software best for large number of users•Also called a “Domain”•Managed servicesClient Server NetworksA network with two or more clients and one server.FTP client enables “client” to contact “server”The Internet – WANWide Area Network•An interconnected network of smaller networks–Schools and Government –Commercial Entities–Residential Users–Access Providers•Common set of mostly-open protocolsInternet History -- WAN•1957: Sputnik launched•1958: ARPA formed under DOD–“Come up with a bomb proof network”•1961: Packet Switching –Network Protocol, precursor of TCP(cont)First Internet: 1969Stanford 12KB of RAMFirst Internet: 1969Stanford #1: 12KB of RAMInternet History (cont)•1975 First Email sent•1978 First Virus•1986 NSFnet•1988 First Chat•1989 First “commercial email”•1990 ARPANET ceases to exist•1991 Gopher = Search tool•1991 WWW is developed by Tim Berners-Lee•1993 Mozilla, Mosaic; NetscapeInternet Evolution•Search Tools•Internet 2.0•Content – Web 2.0A Look at PacificNetUnderstanding Ports•A port is a doorway to a connection in the Internet world.•Part of TCP/IP layer –65,535 possible ports•Different layers of TCP/IP use different ports, eg:•Port 80 for web traffic•Port 21 for FTP•Port 25 for emailPort TablePort Scanning & Malicious Probes•It is similar to a thief going through your neighborhood and checking every door and window on each house to see which ones are open and which ones are locked.•Port scanning software sends out a request to each port sequentially and makes a note of which ports responded or seem open to more in-depth
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