1. Abstraction, Privacy, and the Internet

2. What is Abstraction? “The act of withdrawing or removing something” “The act or process of leaving out of consideration one or more properties of a complex object so as to attend to others”

3. Abstraction in Art “It is easy to make something simple sound complex, however it is more difficult to make something complex sound simple.”

4. Abstraction in Life

6. Abstraction in BYOB - Procedural

7. Abstraction in CS “Writing (good) computer programs is the ability to handle abstractions in a precise manner.” - Keith Devlin

8. Abstraction and the Internet – IP Addresses 70.230.24.81  32-bit Each block is an 8 digit binary number Dynamically assigned (DHCP – Dynamic Host Configuration Protocol)  Laptop Static IP address  Web server

9. Abstraction and the Internet – IP Addresses http://computer.howstuffworks.com/dns.htm 198.168.000.001 What is an IP Address? What does an IP address look like? What is its scheme? How many unique IP addresses could that scheme produce? What is IPv6?

10. Abstraction and the Internet – Domain Name Server Domains have a hierarchy  http://cs.ua.edu http://cs.ua.edu EDU – top-level domain  Accredited post-secondary educational US institutions UA – University of Alabama CS – Computer Science department

11. Information sent in Packets Packet consists of two types of data  Control information: source, destination, error detection, sequence  User data Some systems send packets persistently to avoid collisions Delivery not guaranteed How is it sent?

12. Protocols Networks speak the way people do Speaking has certain rules  Speak the same language (English, Spanish, …)  One person speaks at a time  Interruptions are disruptive  Speak with the proper volume  Don’t speak for too long Pete Siemsen - http://nets.ucar.edu/nets/presentations/itn/

13. Protocols By using a protocol, we know  The syntax of a message Fields/format  The semantics of a message Meaning; may illustrate error  What actions required after receiving the message If error received, the file may need to be resent

14. TCP/IP Created by DARPA in 1970s Transmission Control Protocol and Internet Protocol  Also known as Internet Suite Protocol IP moves packets of data from source to destination based on a four byte destination address TCP verifies the correct delivery of data

15. Bits Behind the Scenes

16. Internet Protocols