Networks+&+The+Internet

Networks
-Reduce hardware and software costs -Provide access to a wide range of services and specialized peripheral devices -enable people to work together, regardless of time and place.

OSI (**Open Systems Interconnection)** Model
Sender:
 * application
 * presentation
 * session
 * transport
 * network
 * data link
 * physical

Receiver:

 * Application
 * Presentation
 * Session
 * Transport
 * Network
 * Data Link
 * Physical

Data transmitted in __packets__
3 main components of computer & information security:
 * 1) Confidentiality - prevention of unauthorized disclosure
 * 2) Integrity - prevent unauthorized modification
 * 3) Availability - prevent unauthorized withholding


 * Hardware more visible to criminals. Easy to add, remove, and change

Basics in protecting security
 * passwords
 * firewall
 * anti-virus/anti-spyware software
 * patches
 * backups


 * inception/theft - unauthorized copying**

LAN: Local Area Network WAN: Wide Area Network The internet:
 * extended across a limited geographic area
 * extends across a larger geographic area
 * interconnected networks
 * the worlds biggest WAN


 * __Network Typology__**
 * **Client - Server**
 * **Client:** Local Server
 * **Server:** Remote system that receives and handle requests from many clients concurrently
 * **Peer to Peer (P2P)**
 * each entity can act as a client or a server
 * no central control
 * Used For:
 * File exchanges
 * workgroups
 * **Bus or Tree**
 * features a "backbone" connection
 * connects all computers
 * Smaller client-servers or P2P style networks branch off

Most wired networks use **twisted pair cables** Some networks use:
 * Network Cables**
 * UTP: unshielded twisted pair
 * STP: shielded twisted pair
 * Connector: RJ-45
 * Coaxial cable
 * Fiber optic cable