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Networking

Networking. What are File Servers?. Network – a group of two or more computers connected together for exchanging data/information and sharing resources File Server – centralized computer used for storing (and sharing) programs and files.

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Networking

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  1. Networking

  2. What are File Servers? • Network – a group of two or more computers connected together for exchanging data/information and sharing resources • File Server – centralized computer used for storing (and sharing) programs and files. • Examples: Database server, Web server, mail server, general file servers • Client-server • Client – computer that ‘receives’ data • Server – computer that provides services to a client

  3. Message • A communication that is transferred from one node on a network to another. • E-mail • Web Pages • FTP (File Transfer Protocol)

  4. Networks • Bandwidth • Amount of data that can be transmitted across transmission medium in a certain amount of time • Packet • Data (Web pages, e-mail messages, etc.) is transmitted in bundles called packets • Header • Sender’s IP address • Receiver’s IP address • Protocol • Packet Number • Data

  5. Expansion of Networks • Variations in degree to which networks are used • Busy during day, quiet at night • To keep demand low on networks, many organizations maintain separate small networks and connect those networks

  6. Expansion of Networks • Pass messages between networks The Internet PC PC Switch PC Router PC Switch PC PC

  7. Firewall – Guard Against External Threats • Acts as a barrier between your system and outside world • Ports provide application-routing information for every message • 21 (FTP) • 25 (E-mail) • 80 (HTTP) • 12345 (NetBus – Trojan) *Block* • Firewall screens ports • Norton Internet Security • McAfee Internet Security • Windows XP (blocks only incoming traffic)

  8. Wireless Technology

  9. Wireless Technology • Access Point • Computer connected to the Internet (acts as intermediary) • Name is SSID (example: RoyalAir, RoyalGuest) (to broadcast or not to broadcast?) • Microsoft's Answer • Usually users able to configure security features • Wireless Router– attaches to access point computer • Beacon • Repeating of identifying information by access point • Example: on a 2.4 GHz radio frequency band • Association – Portable wishes to make connection • Radio waves or infrared signals used to communicate with access point • As portable computers move, interact with new access point • If no computers have direct access to the Internet, portable computers still can interact with each other, but not with the Internet

  10. Wireless Technology • Wireless communications • Messages are divided into packets • Packet contains a header • IDs which machine is to receive the data • Infrared signals or radio waves • All wireless computers in an area share the airwaves, receive the same messages and determine if they are the recipient • 802.11b (11 Mbps max. data rate) • 802.11g (54 Mbps max. data rate) • 802.11n (600 Mbps max. data rate) • Maximum range: varies – about 300 feet • Indoor range less than outdoor (less interference) • Bluetooth (1-3 Mbps DTR / range 10 meters)

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