Ict lecture11b,12,13
- 2. Internet A collection of interconnected networks – looks like a single, unified network
- 3. Internet Enables users located at far-way locations to easily share information with others located all over the world Enables users to easily and inexpensively communicate with others located all over the world Enables the users to operate and run programs on computers located all over the world The Internet is unlike any previous human invention. It is a world-wide resource, accessible to all of the humankind.
- 4. Key Characteristics Geographic Distribution Global - reaches around the world Robust Architecture Adapts to damage and error Speed Data can travels at near ‘c’ on copper, fiber, airwaves
- 5. Key Characteristics Universal Access Same functionality to everyone Growth Rate The fastest growing technology ever Freedom of Speech Promotes freedom of speech The Digital Advantage Is digital: can correct errors
- 6. Internet Networking Protocol Communications on the Internet is controlled by a set of two protocols: TCP and IP TCP/IP Transmission Control Protocol/Internet Protocol TCP breaks down the message to be sent over the Internet into packets IP routes these packets through the Internet to get them to their destination When the packets reach the destination computer, TCP reassembles them into the original message
- 7. IP Address A unique identifier for a computer on a TCP/IP network Format: four 8-bit numbers separated by periods. Each 8-bit number can be 0 to 255 Example: www.smiu.edu.pk (192.254.232.36)
- 8. Domain Name A domain name is a meaningful, easy- to-remember ‘label’ for an IP address Example: www.smiu.edu.pk (192.254.232.36)
- 9. Domain Name System DNS is the way that Internet domain names are located & translated into IP addresses
- 10. Internet Services FTP Telnet Web eMail Instant messaging VoIP
- 11. File Transfer Protocol (FTP) Used to transfer files between computers on a TCP/IP network (e.g. Internet) Simple commands allow the user to: List, change, create folders on a remote computer Upload and download files Typical use: Transferring Web content from the developer’s PC to the Web server
- 12. Telnet Protocol Using Telnet, a user can remotely log on to a computer (connected to the user’s through a TCP/IP network, e.g. Internet) & have control over it like a local user, including control over running various programs In contrast, FTP allows file operations only Typical use: Configuring and testing of a remote Web server
- 13. Web The greatest, shared resource of information created by humankind A user may access any item on the Web through a URL, e.g. http://smiu.edu.pk/under-graduate-programs.php Protocol Identifier Server Address Directory & File Name
- 14. E-Mail Computer-to-computer messaging Components: eMail Clients Programs used for writing, sending, receiving, and displaying eMail messages Example: YahooMail SMTP: Simple Mail Transfer Protocol A protocol used to send and receive eMail messages over a TCP/IP network POP3: Post Office Protocol A protocol used for receiving eMail messages A POP3 server maintains text files (one file per user account) containing all messages received by a user
- 15. Instant Messaging The IM services available on the Internet (e.g. ICQ, AIM, MSN Messenger, Yahoo! Messenger) allow us to maintain a list of people (contacts) that we interact with regularly We can send an instant messages to any of the contacts in our list as long as that contact is online
- 16. Voice over IP (VoIP) Voice delivered from one device to another using the Internet Protocol Voice is first converted into a digital form, is broken down into packets, and then transmitted over a TCP/IP network (e.g. Internet)
- 17. Data & Information Data refers to raw facts & figures Information is an organized form of data
- 18. Data Integrity Integrity refers to maintaining the correctness and consistency of the data – Correctness: Free from errors – Consistency: No conflict among related data items Integrity can be compromised in many ways: – Typing errors – Transmission errors – Hardware malfunctions – Program bugs – Viruses – Fire, flood, etc.
- 19. Database A collection of data organized in such a fashion that the computer can quickly search for a desired data item
- 20. Database Management System DBMS takes care of the storage, retrieval, and management of large data sets on a database It provides SW tools needed to organize & manipulate that data in a flexible manner It includes facilities for: – Adding, deleting, and modifying data – Making queries about the stored data – Producing reports summarizing the required contents
- 21. Database Characteristics Similar items of data form a column Fields placed in a particular row are strongly interrelated One can sort the table w.r.t. any column That makes searching straight forward e.g., for all the books written by a certain author Similarly, searching for the 10 cheapest/most expensive books can be easily accomplished through a sort Effort required for adding a new column to the table is much smaller
- 22. Example Title Author Publisher Price InStock The Terrible Twins Bhola Champion BholiBooks 199 Y Calculus & Analytical Geometry Smith Sahib Good Publishers 325 N Accounting Secrets Zamin Geoffry Sung-e- Kilometer Publishers 29 Y
- 23. Example Customer Title Shipment Type Saad The Terrible Twins 24-10-2014 Air Asad Calculus & Analytical Geometry 23-03-2014 Surface Ali Accounting Secrets 12-06-2014 Air They share a column, & are related through it A program can match info from a field in one table with info in a corresponding field of another table to generate a 3rd table that combines requested data from both tables
- 24. Question who has spent the most money on the online bookstore
- 25. Answer Customer Price Saad 199 Asad 325 Ali 29
- 26. Relational Database Databases consisting of two or more related tables are called relational databases A typical relational database may have anywhere from 10 to over a thousand tables Each column of those tables can contain only a single type of data (contrast this with spreadsheet columns!) Table rows are called records; row elements are called fields A relational database stores all its data inside tables, and nowhere else All operations on data are done on those tables or those that are generated by table operations
- 27. RDBMS Relational DBMS software Contains facilities for creating, populating, modifying, and querying relational databases Examples: –Access – DB2 –FileMaker Pro – Objectivity/DB –SQL Server – MySQL –Oracle – Postgres
- 28. Terminologies Primary Key is a field that uniquely identifies each record stored in a table Queries are used to view, change, and analyze data. They can be used to: – Combine data from different tables, efficiently – Extract the exact data that is desired Forms can be used for entering, editing, or viewing data, one record at a time Reports are an effective, user-friendly way of presenting data. Data normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: – Eliminate redundant data – Storing only related data in a table
- 29. Cyber Crime 07 February 2000 • Users trying to get on to the Web sites of Yahoo, couldn’t! • Reason: Their servers were extremely busy! • They were experiencing a huge number of hits • The hit-rate was superior to the case when a grave incident (e.g. 9/11) occurs, and people are trying to get info about what has happened • The only problem was that nothing of note had taken place! What was going on? • A coordinated, distributed DoS (Denial of Service) attack was taking place • Traffic reached 1 GB/s; many times of normal! • In the weeks leading to the attack, there was a noticeable rise in the number of scans that Internet servers were receiving • Many of these scans appeared to originate from IP addresses that traced back to Korea, Indonesia, Taiwan, Australia
- 30. Three Phases of the DoS 1. Search for Drones • The attackers set about acquiring the control over the computers to be used in the attack … • by scanning – using e.g. Sscan SW – a large numbers of computers attached to the Internet • Once a computer with a weak security scheme is identified, the attackers try a break-in • Once conquered, that computer – called a drone – will be used to scan others 2. Arming the Drones • After several drones have been conquered, the DoS SW is loaded on to them • Examples: Tribal Flood Network, Trinoo, TFN2K • Like a time-bomb, that SW can be set to bring itself into action at a specified time • Alternatively, it can wait for a commencement command from the attacker 3. The Actual Attack • At the pre-specified time or on command, the SW implanted on all of the drones wakes-up and starts sending a huge number of messages to the targeted servers • Responding to those messages overburdens the targeted servers and they become unable to perform their normal functions
- 31. DoS Attack: A Cyber Crime DoS is a crime, but of a new type - made possible by the existence of the Internet A new type of policing and legal system is required to tackle such crimes and their perpetrators Internet does not know any geographical boundaries, therefore jurisdiction is a key issue when prosecuting the cyber-criminal Cyber crime can be used to … Damage a home computer Bring down a business Weaken the telecom, financial, or even defense-related systems of a country
- 32. Viruses Self-replicating SW that eludes detection and is designed to attach itself to other files Infects files on a computers through: – Floppy disks, CD-ROMs, or other storage media – The Internet or other networks Viruses cause tens of billions of dollars of damage each year One such incident in 2001 – the LoveBug virus – had an estimated cleanup/lost productivity cost of US$8.75 billion The first virus that spread world-wide was the Brain virus, and was allegedly designed by someone in Lahore
- 33. Antivirus SW Designed for detecting viruses & inoculating Continuously monitors a computer for known viruses and for other tell-tale signs like: – Most – but, unfortunately not all – viruses increase the size of the file they infect – Hard disk reformatting commands – Rewriting of the boot sector of a hard disk The moment it detects an infected file, it can automatically inoculate it, or failing that, erase it
- 34. THANK YOU