Introduction to the Use of Computers Andrei Gurtov

9.2 Course Outline Internet Unix Word processing HTML Spreadsheets Presentations Graphics Peripherals TeX

9.3 The Course Registration: Lectures – Tuesdays A320 Practice sessions – Tuesdays D326 Exercise Exam (Resit exam)

9.4 Course Book Computer ConfluenceComputer Confluence by George Beekman, 4th Edition, Addison Wesley 2001.

9.5 Computer Labs Free to use everywhere in CS building if not reserved for special purpose or classes Linux and Windows To change between them, reboot –From Windows, choose Start, then Reboot –From Linux, press Ctrl-Alt-Backspace, then Ctrl-Alt-Del

9.6 Accounts You must have an account to participate in practice sessions starting next week! If your major is Computer Science –Contact Pekka Niklander, B425, tel. (09) If not –First apply for Computer Center account –Fill the form, bring to your department –You need both Unix and Windows account –When you get it, contact Pekka for CS account

Lecture 1 The Internet: technology and services

9.8 Internet Technologies

9.9 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

9.10 The Internet: A Network of Networks The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions.

9.11 WAN (Wide Area Network) LAN (Local Area Network) Networks Near and Far There are two general types of computer networks:

9.12 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

9.13 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)

9.14 WAN (Wide Area Network) WANs are often made up of LANs

9.15 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

9.16 Client/Server Model

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

9.18 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

9.19 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.

9.20 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

9.21 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

9.22 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

9.23 Internet Services

9.24 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.

9.25 Web Addresses URL (Uniform Resource Locator): addresses for the World Wide Web. http (hypertext transfer protocol): the protocol of the WWW

9.26 Searching the Web A directory (also an index) is a hierarchical catalog of Web sites compiled by researchers.

9.27 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.

9.28 on the Internet (one-on-one communication). Pine - UNIX-based mail program. MIME - Multipurpose Internet Mail Exchange - allows you exchange files through . Outlook express and Netscape provide more advanced mail readers

9.29 Disadvantages of Works only if the recipient responds Authentication is not ensured is not private Can be overwhelming (SPAM) Both filter out many human components of communication

9.30 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

9.31 Example of a mailing list is an list meant for distributing information among foreign students at the University of Helsinki. Instructions on how to USE and LEAVE the mailing list are available at the ESN website: Before posting mail to the mailing list, be sure that you have read the NETIQUETTE of this list: netiquette.htmlhttp:// netiquette.html

9.32 Mailing list (cont) To subscribe mail in message body subscribe To unsubscribe mail in message body un subscribe foreign- Remember, the machine is stupid so write exactly as above and try several times if it fails Never send these requests to the mailing list itself

9.33 Mailing list (cont) Contact the list administrator with related problems at Do not start or participate in flaming I.e. making offensive comments about the person, spelling mistakes, etc. If you do, the administrator can remove you from the list

9.34 Other features Attachments (one MB files are ok) Filters Ignore sender Group by conversation Work offline Encryption and signature

9.35 News groups News (BBS) and web forums are an alternative for mailing lists Most news groups maintain Frequently Asked Questions (FAQ) Read FAQ before posting questions Web browsers like Netscape and IE have tools for reading news

9.36 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

9.37 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

9.38 Streaming Listen to music from live radio stations Using RealPlayer or Microsoft Media Player E.g. provides links to several life stationswww.yle.fi You can even find live air traffic control –Pilots talking to a dispatcher

9.39 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

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

9.41 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 E-Commerce

9.42 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

9.43 Rules of Thumb: On-line Survival Tips Protect your privacy Cross-check on-line information sources Netiquette Avoid information overload