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מערכות מידע האוניברסיטה העברית – מוטי צוילינג מבוא לתקשורת מחשבים ואינטרנט Course Outline Internet Unix Word processing HTML Spreadsheets Presentations Graphics Peripherals The Internet: technology and services Internet Technologies The UNIX Connection

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מערכות מידע

האוניברסיטה העברית – מוטי צוילינג

course outline
Course Outline
  • Internet
  • Unix
  • Word processing
  • HTML
  • Spreadsheets
  • Presentations
  • Graphics
  • Peripherals
the unix connection
The UNIX Connection
  • The Internet has grown out of UNIX Operating System
  • Some Internet terms (email address) and services (FTP) become more clear after we cover UNIX
the internet a network of networks
The Internet: A Network of Networks

The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions.

networks near and far
Networks Near and Far
  • There are two general types of computer networks:
  • LAN(Local Area Network)
  • WAN(Wide Area Network)
lan local area network
LAN (Local Area Network)
  • A LAN is a network in which the computers are physically close to each other
    • LAN networks are usually set up to share peripherals, such as printers and network servers
    • Each computer andshared peripheral isa node on the LAN
wan wide area network
WAN (Wide Area Network)
  • A WAN is a network in which the computers are a great distance from one another
    • Connections are madevia telephone lines, satellites, and/ormicrowave relay towers
    • Each network site is anode
wan wide area network11
WAN (Wide Area Network)
  • WANs are often made up of LANs
communication with modem
Communication with Modem
  • A modem is needed to connect a computer to a phone line
  • The computercommunicateswith digital signals
  • The telephone systemwas designed to transmit voice signals which are analog
internet protocols
Internet Protocols

TCP/IP (Transmission Control Protocol/Internet Protocol) is the protocol at the heart of the Internet.

internet protocols15
Internet Protocols
  • TCP/IP translates into:
    • TCP (transmission control protocol) breaks messages into packets.
    • IP (Internet protocol) is the addressing for the packets.
    • computer in the Internet (host) is identified by IP address (e.g. 128.214.9.225)
    • IP addresses run out
internet addresses
Internet Addresses

An Internet address is made up of two parts separated by the @ symbol:

  • the person’s user name
  • the host name

The host is named using DNS (domain name system), which translates IP addresses into a string of names.

internet addresses17
Internet Addresses

An Internet address includes: username@hostname.sub.dom

username is the person’s “mailbox”

hostname is the name of the host computer and is followed by one or more domains separated by periods:

  • host.subdomain.domain
  • host.domain
  • www.cs.helsinki.fi
  • gurtov@cs.helsinki.fi (Andrei.Gurtov@Helsinki.FI alias)
internet addresses18
Internet Addresses

Top level domains include:

  • .edu - educational sites
  • .com - commercial sites
  • .gov - government sites
  • .mil - military sites
  • .net - network administration sites
  • .org - nonprofit organizations
intranets
Intranets
  • Intranets – internal closed networks of organizations that are designed using the same technology as the Internet.
  • Firewalls - used to prevent unauthorized communication and secure sensitive internal data.
  • Virtual Private Networking (VPN) -- a way to access intranets from public Internet
the world wide web browsing the web
The World Wide Web:Browsing the Web

WWW is a distributed browsing and searching systems developed by CERN.

Use hypertext links and navigational aids to explore information on the Internet.

web addresses
Web Addresses

URL (Uniform Resource Locator): addresses for the World Wide Web.

http (hypertext transfer protocol): the protocol of the WWW

searching the web
Searching the Web
  • A directory (also an index) is a hierarchical catalog of Web sites compiled by researchers.
searching the web24
Searching the Web
  • A search engine offers a more complete database of what is one the WWW. A software robot or spider retrieves the entries according to key word queries.
email on the internet
Email on the Internet
  • Email (one-on-one communication).
  • Pine - UNIX-based mail program.
  • MIME - Multipurpose Internet Mail Exchange - allows you exchange files through email.

Outlook express and Netscape

provide more advanced mail

readers

disadvantages of email
Disadvantages of Email
  • Works only if the recipient responds
  • Authentication is not ensured
  • Email is not private
  • Can be overwhelming (SPAM)
  • Both filter out manyhuman componentsof communication
mailing lists and newsgroups
Mailing Lists and Newsgroups
  • Email is a valuable tool for one-to-one communication
  • Mailing lists allow you to participate in email discussion groups on special-interest topics.
  • Usenet Newsgroups are virtual bulletin boards that you access with a news reader
other email features
Other email features
  • Attachments (one MB files are ok)
  • Filters
  • Ignore sender
  • Group by conversation
  • Work offline
  • Encryption and signature
remote access and file transfer
Remote Access and File Transfer

The most popular use of the Internet is information discovery and retrieval. Because the Internet is unorganized, you can use the following tools:

Telnet: for remote login to other computers.

FTP: file transfer protocol; transfer files from remote computers.

SSH: secure remote login and file transfer

paging and chatting
Paging and chatting

Talk is a UNIX program that allows you to carry on a split-screen communication

Internet relay chat (IRC) allows several users to type simultaneously

ICQ (I seek you): user-friendly messaging system

  • Microsoft Messenger is a similar tool
streaming
Streaming
  • Listen to music from live radio stations
  • Using RealPlayer or Microsoft Media Player
  • E.g. www.yle.fi provides links to several life stations
  • You can even find live air traffic control
    • Pilots talking to a dispatcher
file sharing
File sharing
  • Search and download files like latest hits (mp3), blockbuster movies (mpeg), latest software packages (zip),pictures...
  • Make your own files available to others
  • Tools like Gnutella or Napster
  • Difficult for authorities to snap these systems to their distributed nature
real time communication
Real-Time Communication

Video telephony (see, hear, and type to another person).

  • MBONE - Multicast Backbone – centralized distribution
  • NetMeeting – works over ”off-the-shelf” Internet
e commerce
E-Commerce
  • Users connect (usually for a fee) to a variety of on-line databases
  • On-line databases include:
    • current stock market status
    • digital libraries
    • banking
    • shopping
online banking
Online banking
  • Provided in Finland by all major banks
  • E.g. in Leonia costs less than any other service package
  • You get a customer number and a PIN code to log-in at their web site
  • You get a challenge-response table of codes
  • All connections are encrypted
  • Within the same bank money are moved instantly, otherwise it takes a couple of days
rules of thumb on line survival tips
Rules of Thumb: On-line Survival Tips
  • Protect your privacy
  • Cross-check on-lineinformation sources
  • Netiquette
  • Avoid informationoverload