1. Internet Technologies Presenter: Samuel Wagema Mob: 0772663310/0701663310 Email: afric2040@gmail.com

2. Coursework  Scan through your experience and exposure and then develop a static website using HTLM tags ONLY.  Note: Your website should at least have more than 15 links. Internet Technologies 2

3.  Internet  Internet is defined as an Information super Highway, to access information over the web.  Internet uses the standard Internet Protocol (TCP/IP).  Every computer in internet is identified by a unique IP address.  IP Address is a unique set of numbers (such as 192.168.1.10) which identifies a computer location.  A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name. Internet Technologies 3

4. Advantages  Internet serves a medium for entertainment. Following are the various modes for entertainment over internet.  Online Television  Online Games  Songs  Videos  Social Networking Apps Internet Technologies 4

5. 2. Internet allows us to communicate with the people sitting at remote locations. There are various apps available on the wed that uses Internet as a medium for communication. One can find various social networking sites such as:  Facebook  Twitter  Yahoo  Google+  Flickr  Orkut Internet Technologies 5

6. 3.Internet provides concept of electronic commerce, that allows the business deals to be conducted on electronic systems 4. Internet allows us to use many services like:  Internet Banking  Matrimonial Services  Online Shopping  Online Ticket Booking  Online Bill Payment  Data Sharing  E-mail Internet Technologies 6

7. Disadvantages  There are always chances to loose personal information such as name, address, credit card number. Therefore, one should be very careful while sharing such information. One should use credit cards only through authenticated sites.  Another disadvantage is the Spamming.Spamming corresponds to the unwanted e-mails in bulk. These e-mails serve no purpose and lead to obstruction of entire system. Internet Technologies 7

8.  Virus can easily be spread to the computers connected to internet. Such virus attacks may cause your system to crash or your important data may get deleted.  Also a biggest threat on internet is pornography. There are many pornographic sites that can be found, letting your children to use internet which indirectly affects the children healthy mental life.  There are various websites that do not provide the authenticated information. This leads to misconception among many people. Internet Technologies 8

9.  Intranet  Intranet is defined as private network of computers within an organization with its own server and firewall.  PCs in intranet are not available to the world outside of the intranet.  Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet. Internet Technologies 9

10. Benefits  Communication  Intranet offers easy and cheap communication within an organization. Employees can communicate using chat, e-mail or blogs.  Time Saving  Information on Intranet is shared in real time.  Collaboration  Information is distributed among the employees as according to requirement and it can be accessed by the authorized users, resulting in enhanced teamwork. Internet Technologies 10

11.  Platform Independency  Intranet can connect computers and other devices with different architecture.  Cost Effective  Employees can see the data and other documents using browser rather than printing them and distributing duplicate copies among the employees, which certainly decreases the cost.  Workforce Productivity  Data is available at every time and can be accessed using company workstation. This helps the employees work faster. Internet Technologies 11

12.  Business Management  It is also possible to deploy applications that support business operations.  Security  Since information shared on intranet can only be accessed within an organization, therefore there is almost no chance of being theft.  Specific Users  Intranet targets only specific users within an organization therefore, once can exactly know whom he is interacting. Internet Technologies 12

13. Internet vs. Intranet Internet Technologies 13

14.  Extranet  Extranet refers to network within an organization, using internet to connect to the outsiders in controlled manner.  It helps to connect businesses with their customers and suppliers and therefore allows working in a collaborative manner. Eg UMI Kampala branch can collaborate with UMI Mbarara branch Internet Technologies 14

15.  Implementation  Extranet is implemented as a Virtual Private Networks (VPN) because it uses internet to connect to corporate organization and there is always a threat to information security.  VPN offers a secure network in public infrastructure (Internet). Internet Technologies 15

16.  benefits  Extranet proves to be a successful model for all kind of businesses whether small or big. Here are some of the advantages of extranet for employees, suppliers, business partners, and customers: Internet Technologies 16

17. Internet Technologies 17

18. Challenges associated with Extranets  Hosting  Where the extranet pages will be held i.e. who will host the extranet pages. In this context there are two choices: i) Host it on your own server. ii) Host it with an Internet Service Provider (ISP) in the same way as web pages.  But hosting extranet pages on your own server requires high bandwidth internet connection which is very costly. Internet Technologies 18

19.  Security  Additional firewall security is required if you host extranet pages on your own server which result in a complex security mechanism and increase work load.  Accessing Issues  Information can not be accessed without internet connection. However, information can be accessed in Intranet without internet connection. Internet Technologies 19

20. Extranet vs. Intranet Internet Technologies 20

21. Network “... communication system for connecting end-systems” End-systems a.k.a. “hosts” PCs, workstations dedicated computers network components Internet Technologies 21

22. Multiaccess vs. Point-to-point  Multiaccess means shared medium.  many end-systems share the same physical communication resources (wire, frequency,...)  There must be some arbitration mechanism.  Point-to-point  only 2 systems involved  no doubt about where data came from ! Internet Technologies 22

23. LAN - Local Area Network  connects computers that are physically close together ( < 1 mile).  high speed  multi-access  Technologies:  Ethernet10 Mbps, 100Mbps  Token Ring16 Mbps  FDDI 100 Mbps Internet Technologies 23

24. WAN - Wide Area Network  connects computers that are physically far apart. “long-haul network”.  typically slower than a LAN.  typically less reliable than a LAN.  point-to-point  Technologies:  telephone lines  Satellite communications Internet Technologies 24

25. Internetwork  Connection of 2 or more distinct (possibly dissimilar) networks.  Requires some kind of network device to facilitate the connection. Net ANet B Internet Technologies 25

26. The Internet  millions of connected computing devices: hosts = end systems  running network apps  communication links  fiber, copper, radio, satellite  routers: forward packets (chunks of data) Internet Technologies 26 Home network Institutional network Mobile network Global ISP Regional ISP router PC server wireless laptop cellular handheld wired links access points

27. The Internet Internet Technologies 27 Internet Mapping Project, Bill Cheswick

28. A Network of Networks  roughly hierarchical  Tier-1 ISPs provide national, international coverage  Tier-2 ISPs provide regional coverage  Tier-3 and lower levels provide local coverage  any tier may sell to business and residential customers  any ISP may have a link to any other ISP (not strictly hierarchical) Internet Technologies 28

29. Many Different Internet Service Providers  Each network is independent  Interoperability requires using Internet standards: IP, TCP  the Internet is global and must run these standards  your private intranet can do whatever you want it to do Internet Technologies 29

30. Internet Design Goals  primary goal: interoperability among existing networks  a network of networks  obey administrative boundaries  secondary goals  fault tolerance  multiple transport protocols  support a variety of networks  distributed management  cost effective, low effort for host attachment, accountability  first three were more important, so remaining four did not receive as much attention  no mention of security Internet Technologies 30

31. Internet Design Principles  minimal assumptions about services network should support  ability to send packets  no reliability or security  end-to-end principle  keep the core of the network as simple as possible,  put complex functionality at the edges  exception: significant performance improvement Internet Technologies 31

32. Network Models  Using a formal model allows us to deal with various aspects of Networks abstractly.  We will look at a popular model (OSI reference model).  The OSI reference model is a layered model. Internet Technologies 32

33. Layering  Divide a task into pieces and then solve each piece independently (or nearly so).  Establishing a well defined interface between layers makes porting easier.  Major Advantages:  Code Reuse  Extensibility Internet Technologies 33

34. The Internet Hourglass Internet Technologies 34

35. The Internet at each Hop Internet Technologies 35

36.  Interface protocols describe communication between layers on the same endpoint.  Peer-to-peer protocols describe communication between peers at the same layer. Interface and Peer-to-peer Protocols Process Transport Network Data Link Process Transport Network Data Link Interface Protocols Peer-to-peer Protocols Internet Technologies 36

37. What’s a protocol? human protocols:  “what’s the time?”  “I have a question”  introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols:  machines rather than humans  all communication activity in Internet governed by protocols Internet Technologies 37

38. What’s a protocol? a human protocol and a computer network protocol: Internet Technologies 38 Q: Other human protocols? Hi Got the time? 2:00 TCP connection request TCP connection response Get http://www.awl.com/kurose-ross time

39. Protocol  An agreed upon convention for communication.  both endpoints need to understand the protocol.  Protocols must be formally defined and unambiguous!  Protocols define  format,  order of msgs sent and received among network entities,  actions taken on msg transmission, receipt  We will study lots of existing protocols and perhaps develop a few of our own. Internet Technologies 39

40. Programs & Processes  A program is an executable file.  A process or task is an instance of a program that is being executed.  A single program can generate multiple processes. Internet Technologies 40

41. Client - Server  A server is a process - not a machine !  A server waits for a request from a client.  A client is a process that sends a request to an existing server and (usually) waits for a reply. Internet Technologies 41

42. Client - Server Examples  Server returns the time-of-day.  Server returns a document.  Server prints a file for client.  Server does a disk read or write.  Server records a transaction. Internet Technologies 42

43. Servers  Servers are generally more complex (more interesting).  Basic types of servers:  Iterative - server handles one client at a time.  Concurrent - server handles many clients at a time.  We will study the differences later. Internet Technologies 43

44. Thought Exercise  Come up with an example of a layered system.  Describe the interface and peer-to-peer protocols for your example. Internet Technologies 44

45. Layering Example: Federal Express  Letter in envelope, address on outside  FedX guy adds addressing information, barcode.  Local office drives to airport and delivers to hub.  Sent via airplane to nearest city.  Delivered to right office  Delivered to right person Letter Addressed Envelope Addressed Envelope Internet Technologies 45