Session 8 Networking & Operating Systems

1. Nassau Community College ITE153 – Operating Systems Session 8Networking & Operating Systems

2. Nassau Community College ITE153 – Operating Systems

3. Introduction Nassau Community College ITE153 – Operating Systems Networking & Operating Systems

4. How It All Started Nassau Community College ITE153 – Operating Systems 1969

5. How It All Started Nassau Community College ITE153 – Operating Systems 1969

6. Internet History Nassau Community College ITE153 – Operating Systems • Evolved from ARPANet (Defense Department’s Advanced Research Projects Agency Network) • ARPANet was developed in 1969, and was the first packet-switching network • Initially, included only four nodes: UCLA, UCSB, Utah, and SRI

7. NSF and the Internet Nassau Community College ITE153 – Operating Systems • In the 1980s, NSFNet extended packet-switched networking to non-ARPA organization; eventually replaced ARPANet • Instituted Acceptable Use Policies to control use • CIX (Commercial Internet eXchange) was developed to provide commercial internetworking

8. The World Wide Web Nassau Community College ITE153 – Operating Systems • Concept proposed by Tim Berners-Lee in 1989, prototype WWW developed at CERN in 1991 • First graphical browser (Mosaic) developed by Mark Andreessen at NCSA • Client-server system with browsers as clients, and a variety of media types stored on servers popped up everywhere • Uses HTTP (Hyper Text Transfer Protocol) for retrieving files

9. Connecting to the Internet Nassau Community College ITE153 – Operating Systems • End users get connectivity from an ISP (Internet Service Provider) • Home users use dial-up, ADSL, cable modems, satellite, wireless • Businesses use dedicated circuits connected to LANs • ISPs use “wholesalers” called network service providers and high speed (T-3 or higher) connections

10. US Internet Access Points Nassau Community College ITE153 – Operating Systems

11. Internet Addressing Nassau Community College ITE153 – Operating Systems • 32-bit global Internet address • Includes network and host identifiers • Dotted decimal notation • 11000000 11100100 00010001 00111001 (binary) • 192.228.17.57 (decimal)

12. Internet Addressing Nassau Community College ITE153 – Operating Systems

13. Network Classes Nassau Community College ITE153 – Operating Systems • Class A: Few networks, each with many hostsAll addresses begin with binary 0Range: 1-126 • Class B: Medium networks, medium hostsAll addresses begin with binary 10Range: 128-191 • Class C: Many networks, each with few hosts All addresses begin with binary 11Range: 192-223

14. Domain Name System Nassau Community College ITE153 – Operating Systems • 32-bit IP addresses have two drawbacks • Routers can’t keep track of every network path • Users can’t remember dotted decimals easily • Domain names address these problems by providing a name for each network domain (hosts under the control of a given entity)

15. DNS Database Nassau Community College ITE153 – Operating Systems • Hierarchical database containing name, IP address, and related information for hosts • Provides name-to-address directory services

16. Domain Tree Nassau Community College ITE153 – Operating Systems

17. IP, Protocols, Routing, Layers Nassau Community College ITE153 – Operating Systems Networking & Operating Systems

18. Private Networks Nassau Community College ITE153 – Operating Systems • Isolated to individual organizations • Emergence of computer security • Sharing a system • Protecting data

19. Nassau Community College ITE153 – Operating Systems Networking • Networks start talking to each other • Gateways • Arpanet • TCP/IP Everywhere • Vinton Cerf, “IP On Everything!”

20. Maturing of the Internet Nassau Community College ITE153 – Operating Systems • Telephones used by 50% of worlds population • Internet attained similar level of growth in 2010 – approaching max growth • Connecting computers and programmable devices • More devices than people • Internet of Things

21. Nassau Community College ITE153 – Operating Systems Early Hacking • Cap’n Crunch cereal prize • Giveaway whistle produces 2600 MHz tone • Blow into receiver – free phone calls • “Phreaking” encouraged by Abbie Hoffman • Doesn’t hurt anybody

22. Nassau Community College ITE153 – Operating Systems Captain Crunch • John Draper • `71: Bluebox built by many • Jobs and Wozniak were early implementers • Developed “EasyWriter” for first IBM PC • High-tech hobo • Whitehat hacker

23. Protocols in a Simplified Architecture Nassau Community College ITE153 – Operating Systems

24. Protocol Data Units Nassau Community College ITE153 – Operating Systems

25. Operation of a Protocol Architecture Nassau Community College ITE153 – Operating Systems

26. TCP and UDP Headers Nassau Community College ITE153 – Operating Systems

27. IP Headers Nassau Community College ITE153 – Operating Systems 32-bitfield QoS max # allowable hops 128-bit field

28. TP/IP Concepts Nassau Community College ITE153 – Operating Systems

29. Client-Server Model Nassau Community College ITE153 – Operating Systems • The client–server model of computing is a distributed application that partitions tasks or workloads between the providers of a resource or service, called servers (daemons), and service requesters, called clients.

30. Daemons Aren’t Evil Nassau Community College ITE153 – Operating Systems Daemon is a computer program that runs in the background, rather than under the direct control of a user; they are usually initiated as background processes • Developers began to use the word daemon to describe background processes which worked tirelessly to perform system chores • ftpd, httpd, smtpd – look for the “d” suffix • Windows calls these services

31. PDUs in TCP/IP Nassau Community College ITE153 – Operating Systems User Data Application Byte Stream TCPHeader User Data TCPSegment IPHeader User Data IP Datagram NetworkHeader User Data Network-level Packet

32. Some TCP/IP Protocols Nassau Community College ITE153 – Operating Systems

33. Assigned Port Numbers Nassau Community College ITE153 – Operating Systems Port Service Port Service 7 echo 110 pop3 20 ftp-data 119 nntp 21 ftp 123 ntp 23 telnet 389 ldap 25 smtp 443 https 39 rip 500 isakmp 53 DNS 520 rip2 80 http 1812 radiusauth 88 kerberos 2049 Sun NFS

34. Alternate Routing Diagram Nassau Community College ITE153 – Operating Systems

35. Hands-onExercises Nassau Community College ITE153 – Operating Systems

36. Hands-On Nassau Community College ITE153 – Operating Systems • Examine some sites using whoisand traceroute for the domain name and the IP address. See how much you can find out about a site • Try: whois ncc.edu • Try: traceroute www.google.com

37. Important URLs Nassau Community College ITE153 – Operating Systems • http://www.networksolutions.com/whois/index.jhtml-the original InterNIC. This site has the “whois” database • http://www.arin.net- American registry for Internet numbers. This site has a “whois” database for IP numbers • http://network-tools.com/ - tools: traceroute, ping, nslookup, whois, dig

38. Homework Nassau Community College ITE153 – Operating Systems • Review the Slides • Work on the Take Home Exam • Due next Monday at the latest • Do the Exercise: “whois and traceroute”

39. The Internet Highway…a parting thought Nassau Community College ITE153 – Operating Systems • There is a road, no simple highway, • Between the dawn and the dark of night, • And if you go no one may follow, • That path is for your steps alone.