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  1. 1. What is the Internet?• A network of networks, joining many government,university and private computers together and providingan infrastructure for the use of E-mail, bulletin boards, filearchives, hypertext documents, databases and othercomputational resources• The vast collection of computer networks which form andact as a single huge network for transport of data andmessages across distances which can be anywhere fromthe same office to anywhere in the world.
  2. 2. What is the Internet?• The largest network of networks in the world.• Uses TCP/IP protocols and packet switching.• Runs on any communications substrate.
  3. 3. Brief History of the Internet• 1968 - DARPA (Defense Advanced Research Projects Agency)contracts with BBN (Bolt, Beranek & Newman) to createARPANET• 1970 - First five nodes:– UCLA– Stanford– UC Santa Barbara– U of Utah, and– BBN• 1974 - TCP specification by Vint Cerf• 1984 - On January 1, the Internet with its 1000 hostsconverts en masse to using TCP/IP for its messaging
  4. 4. Internet Growth Trends• 1977: 111 hosts on Internet• 1981: 213 hosts• 1983: 562 hosts• 1984: 1,000 hosts• 1986: 5,000 hosts• 1987: 10,000 hosts• 1989: 100,000 hosts• 1992: 1,000,000 hosts• 2001: 150 – 175 million hosts• 2002: over 200 million hosts• By 2014, about 90% of the planet will be on the Internet
  5. 5. TCP/IP Addresses• Every host on the Internet must have aunique IP address• The IP address is a 32-bit number whichwe write in dotted decimal notation• The first part of the IP address is thenetwork address – the remainder is thehost ID• A subnet mask is used to determine thenetwork address from a IP host address• All hosts on the same network areconfigured with the same subnet mask
  6. 6. Network Address ExampleHost address: mask: obtain the network address, AND the hostIP with its subnet mask:
  7. 7. Obtaining an Internet NetworkAddress• IP network addresses must be unique, orthe Internet will not be stable• The Internet Network Information Centre(InterNIC) was originally responsible forissuing Internet network addresses• Today, the Internet Assigned NumberAuthority (IANA) issues networkaddresses to Information ServiceProviders (ISPs)• ISPs split networks up into subnets andsell them on to their customers
  8. 8. Domain Name System (DNS)• IP addresses are used to identify hosts on aTCP/IP network• Example:• Numbers are not ‘friendly’ – people prefernames• DNS is a protocol used to map IP addresses totextual names• E.g. www.wlv.ac.uk maps to
  9. 9. DNS on the InternetDNS names have a hierarchical structureExample: www.wlv.ac.ukcom net fr uk usRoot Levelac coaston wlvstaffsftpwwwclunTop-level domainSecond-leveldomainServer name
  10. 10. Internet Email Addresses• The Local part is the name of a specialfile stored on the mail server called theuser’s mailbox• The Domain name is resolved using DNS• The mail server is also known as a mailexchangerLocal part Domain name of mail server@mel.ralph@wlv.ac.uk
  11. 11. Hypertext Transfer Protocol(HTTP)• HTTP is the protocol used to access resourceson the World Wide Web• A browser application is used to send a requestto the WWW server for a resource, e.g. a webpage, graphics file, audio file, etc.• The server responds by sending the resource (afile) to the client and closing the connectionRequestBrowser appWWW serverTheInternet(TCP/IP)TheInternet(TCP/IP)Web page
  12. 12. Uniform Resource Locator (URL)• URL is the standard for specifying thewhereabouts of a resource (such as a web page)on the Internet• A URL has four parts:– The protocol used to retrieve the resource– The host where the resource is held– The port number of the server process on thehost– The name of the resource filehttp://www.wlv.ac.uk:80/index.htmlProtocol Host Port number Name of web page
  13. 13. URL Defaults• A server will normally be setup to use standarddefaults• This enables the URL to be simplified• In the case of a Web server for example– Default port will be 80– Default name for home page will be index.html• Hence the previous URL can be shortened tohttp://www.wlv.ac.uk/
  14. 14. File Transfer Protocol (FTP)• Protocol for copying files between clientand an FTP server• Uses a TCP connection for reliabletransfer of files with error-checking• Most browsers support FTP, or you canuse a dedicated FTP client program, eg.WS_FTP• Trivial File Transfer Protocol (TFTP) is alightweight version for small memorydevicesftp://ftp.demon.co.uk/pub/
  15. 15. Telnet• Telnet allows a user to run commandsand programs remotely on anothercomputer across the Internet• The user runs a Telnet client programon the local host• A Telnet server process must berunning on the remote host• The user must have the necessarypermissions and password to accessthe remote host
  16. 16. Some Port Assignments• 21 FTP• 23 Telnet• 25 SMTP (mail)• 70 gopher• 79 finger• 80 HTTP
  17. 17.  Crime => Illegal activities Cyber => Characteristic of theculture of computers…Computer crime, or cybercrime,refers to any crime that involves acomputer and a networkIt is a criminal activity committed on the Internet .Cyber Crime
  18. 18.  Such conducts includes:• Illegal access• Illegal Transactions• System interference• Data interference• Misuse of devices• Fraud Cyber crime offenses against the information technologyinfrastructure.Cyber Crime <=> Cyber Space <=> Net CrimeCyber Crime
  19. 19. The Invisible Criminals Are Dangerous Than The Visible One…Who is Cyber CriminalThose who are doing crimes by using thecomputer as an target or object.i. Children and adolescents b/w 6-18ii. Dissatisfied employeesiii. Professional hackersiv. Crackers
  20. 20. Cyber Crime VariantsHacking"Hacking" is a crime, which entails crackingsystems and gaining unauthorized access to thedata stored in them. Hacking had witnessed a 37per cent increase this year.Cyber SquattingCyber Squatting is the act of registering a famousDomain Name and then selling it for a fortune.This is an issue that has not been tackled inIT ACT 2000. 
  21. 21. Phishing is just one of the many frauds onthe Internet, trying to fool people intoparting with their money. Phishing refers tothe receipt of unsolicited emails bycustomers of Financial Institutions,requesting them to enter their Username,Password or other personal information toaccess their Account for some reason.The fraudster then has access to thecustomers online bank account and to thefunds contained in that account.
  22. 22. Cyber Stalking is use of the Internet or otherelectronic means to stalk someone. This termis used interchangeably with onlineharassment and online abuse. Stalkinggenerally involves harassing or threateningbehaviour that an individual engages inrepeatedly, such as following a person,appearing at a persons home or place ofbusiness, making harassing phone calls,leaving written messages or objects, orvandalizing a persons property.
  23. 23. Vishing is the criminal practice ofusing social engineering andVoice over IP (VoIP) to gainaccess to private personal andfinancial information from thepublic for the purpose of financialreward. The term is a combinationof “Voice" and phishing. Vishingexploits the publics trust inlandline telephone services. Vishing is typically used to stealcredit card numbers or otherinformation used in identity theftschemes from individuals.VISHINGSaturday 4 May 2013