Lecture01 - The Great Web.pdf

Modern Web Application Development and Exploitation Lecture 01  2 A brief history of the Internet 1960s – Computers are immovable Problem ○ No way to share data ○ Cold War...

Modern Web Application Development and Exploitation Lecture 01  2 A brief history of the Internet 1960s – Computers are immovable Problem ○ No way to share data ○ Cold War Investments in Science, Technology and Space research ARPA - Advanced Research Projects Agency ○ Research on Technology and data sharing This Photo by Unknown Author is licensed under CC BY-SA-NC ○ Established by US Defence Dept. Main goals was to develop a system for sharing data across the country  3 A brief history of the Internet Advanced Research Projects Agency NETwork (ARPANET) ○ Interconnection of universities and research centers ○ 1969 – 1990 ○ Foundation of The Internet ○ First wide-area packet-switched network ○ Research purpose ○ File transfer, communication etc This Photo by Unknown Author is licensed under CC BY-SA  4 The Digital World Digital world Increasing Internet usage From sending a message to Satellite communication Ease of access Fast and reliable What was the reason behind this jump? This Photo by Unknown Author is licensed under CC BY-SA  5 The World Wide Web www or web Foundation of the internet Collection of documents and web resources identified by uniform resource allocator Invented in 1990 by Tim Berners-Lee Communicates using HTTP protocol through browsers How does this communication happens?  6 Everything starts with a link  7 Protocol What is a protocol? ○ Set of rules for communication Need of a protocol Hyper Text Transfer Protocol Transfers Hyper Text documents ○ Uses browser to render hypertext documents HTTP(S) This Photo by Unknown Author is licensed under CC BY-SA-NC ○ HTTP(Secure) ○ Encrypted => HTTP over TLS or HTTP over SSL ○ Protects MitM attacks ○ Privacy and integrity  8 DNS Domain Name System Translates Web address to server address ○ Web address != server address? ○ IP address ○ Port DNS Privacy ○ Queries are in Plain text ○ ISPs can use/sell them for targeted ads ○ Privacy tip Consider using 1.1.1.1 or other privacy based DNS providers This Photo by Unknown Author is licensed under CC BY-SA-NC 9  10 DNS Services & Structure DNS services hostname to IP address translation host aliasing ○ canonical, alias names mail server aliasing load distribution ○ replicated Web servers: many IP addresses correspond to one name  11 Network Architectures Client-Server architecture Peer-to-Peer architecture Clients and server are differentiated Clients and server are not differentiated Focuses on information sharing Focuses on connectivity Centralized server is used to store the data Each peer has the data More stable than Peer-to-Peer Network Less stable if number of peer is increase  12 Network Architectures Client-Server architecture ○ Most common and widely architecture ○ Client will request for a resource/document and Server will server the resource/document ○ Server is the program which servers the resource This Photo by Unknown Author is licensed under CC BY-SA Eg: Apache, Nginx ○ Client is a program which requests for the resource Eg: Browsers, cURL ○ Eg: Wikipedia  13 Network Architectures Peer-to-Peer (P2P) architecture ○ Commonly used for file sharing in closed networks ○ Peers will be connected to each other and resources will be transferred ○ Eg: Torrent This Photo by Unknown Author is licensed under CC BY-ND  14 Things to remember Parts of a link Protocol and it’s need HTTP/HTTPS What, how and why - of DNS, IP and Port Different type of architectures and their working