Introduction to the Use of Computers Andrei Gurtov

 1999 Addison Wesley Longman9.2 Course Outline Internet Unix Word processing HTML Spreadsheets Presentations Graphics Peripherals TeX

 1999 Addison Wesley Longman9.3 The Course Registration: Lectures – Tuesdays A320 Practise sessions – Tuesdays A215 Exercise Exam

 1999 Addison Wesley Longman9.4 Course Book Computer ConfluenceComputer Confluence by George Beekman, 3rd Edition, Addison Wesley 1999.

 1999 Addison Wesley Longman9.5 Computer Labs Free to use everywhere in CS building if not reserved for special purpose or classes Linux and Windows NT Guest account: –login: guest –password: demo

Lecture 1 The Internet: technology and services

 1999 Addison Wesley Longman9.7 Internet Techologies

 1999 Addison Wesley Longman9.8 The UNIX Connection The Internet has grown out of UNIX Operating System Some Internet terms ( address) and services (FTP) become more clear after we cover UNIX

 1999 Addison Wesley Longman9.9 The Internet: A Network of Networks The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions.

 1999 Addison Wesley Longman9.10 WAN (Wide Area Network) LAN (Local Area Network) Networks Near and Far There are two general types of computer networks:

 1999 Addison Wesley Longman9.11 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 and shared peripheral is a node on the LAN

 1999 Addison Wesley Longman9.12 A WAN is a network in which the computers are a great distance from one another –Connections are made via telephone lines, satellites, and/or microwave relay towers –Each network site is a node WAN (Wide Area Network)

 1999 Addison Wesley Longman9.13 WAN (Wide Area Network) WANs are often made up of LANs

 1999 Addison Wesley Longman9.14 A modem is needed to connect a computer to a phone line The computer communicates with digital signals The telephone system was designed to transmit voice signals which are analog Communication á la Modem

 1999 Addison Wesley Longman9.15 Client/Server Model

 1999 Addison Wesley Longman9.16 Internet Protocols TCP/IP (Transmission Control Protocol/Internet Protocol) is the protocol at the heart of the Internet.

 1999 Addison Wesley Longman9.17 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 ) –IP addresses run out

 1999 Addison Wesley Longman9.18 Internet Addresses An Internet address is made up of two parts separated by 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.

 1999 Addison Wesley Longman9.19 Internet Addresses An Internet address includes: 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

 1999 Addison Wesley Longman9.20 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

 1999 Addison Wesley Longman9.21 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

 1999 Addison Wesley Longman9.22 Internet Services

 1999 Addison Wesley Longman9.23 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.

 1999 Addison Wesley Longman9.24 Web Addresses URL (Uniform Resource Locator): addresses for the World Wide Web. http (hypertext transfer protocol): the protocol of the WWW

 1999 Addison Wesley Longman9.25 Searching the Web A directory (also an index) is a hierarchical catalog of Web sites compiled by researchers.

 1999 Addison Wesley Longman9.26 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.

 1999 Addison Wesley Longman9.27 on the Internet (one-on-one communication). Pine - UNIX-based mail program. MIME - Multipurpose Internet Mail Exchange - allows you exchange files through .

 1999 Addison Wesley Longman9.28 Disadvantages of and Teleconferencing Work only if the recipient responds Can be overwhelming (SPAM) Both filter out many human components of communication

 1999 Addison Wesley Longman9.29 Mailing Lists and Newsgroups is a valuable tool for one-to-one communication Mailing lists allow you to participate in discussion groups on special- interest topics. Usenet Newsgroups are virtual bulletin boards that you access with a news reader

 1999 Addison Wesley Longman9.30 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

 1999 Addison Wesley Longman9.31 Real-Time Communication 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

 1999 Addison Wesley Longman9.32 Real-Time Communication Video telephony (see, hear, and type to another person). MBONE - Multicast Backbone – centralized distribution NetMeeting – works over ”off-the-shelf” Internet

 1999 Addison Wesley Longman9.33 Electronic databases allow users to connect (usually for a fee) to a variety of on-line databases On-line databases include: –current stock market status –digital libraries –medical references On-line Databases

 1999 Addison Wesley Longman9.34 Rules of Thumb: On-line Survival Tips Protect your privacy Cross-check on-line information sources Netiquettee Avoid information overload