Introduction to the Internet

History of the Internet

• Soviet Sputnik Satellite prompted Pentagon to start a military competition research for a robust communication system.(1958)
  DARPA: started in the mid 1970s - ARPANET (Cerf: RFC 13; 8/20/69; Cerf and Khan: 'A Protocol for Packet Network Intercommunication' ; 5/74)
• ARPANET and MILNET became the backbones in 1983.
  DARPA funded BBN to implement TCP/IP for use with Unix and funded Berkeley to integrate the TCP/IP into BSD.
  4.2BSD contains many popular utilities on top of TCP. One of the main features is an OS abstraction named socket which provides simple interface to access communication protocol.
• NSF funded NSFNET to connect 6 super computer centers in 1985.
• NSF provided seed money for many regional networks in 1986(DS-0: 56Kbps), 1988(T1: 1.544Mbps), 1990 (T3: 45Mbps)
• Web: In 1989 at CERN, the European Particle Physics Laboratory (Switzerland), Tim Berners-Lee wrote a Web client/server and developed URLs (uniform resource locators) as a common addressing system. Marc Andreessen and Eric Bina (working at NCSA; now working at Netscape chaired by Jim Clark) lead a team that made Mosaic happened in 1993.

The Infrastructure of the Net:

• vBNS: Very high speed backbone network services (Super computer center: NASA, NSF and etc.)
• NAPs: Network access points
  San Francisco Bay area: Pacific Bell/Bellcore
  NY (Pensauken, NJ): Sprint (Switched FDDI)
  Washington DC: Metropolitan Fiber Systems (Switched Ethernet + FDDI)
  Chicago: Ameritech/Bellcore
• Regional Network
• ISPs

Who runs it?

Internet Society (ISOC): An international non-profit organization(1992) ISOC maintains and extends the development of the Internet and its associated technologies.

Internet Activities Board (IAB): Internet Task Force (IETF and IRTF).

Connecting to the Net:

• Direct connection: T1/T3
• On-demand: Modem/PC/Phone line with SW: SLIP 9Serial Line Internet Protocol) PPP(Point to Point Protocol).
  Connect to your school/office
  Connect to on-line service (AOL)
  Connect to ISPs: Erols, CAIS and etc.

  ISDN (Integrated Service Digital Network): Contains 3 channels (i.e. 2B+D; B: conversations/data D: signal) Capable of handling 64 - 128 kbps up to 3 telephone devices.
  Modem Cable: operate over two-way HFC (hybrid fiber/coax; 20 -100 times faster than regular modem)
  ADSL (Asymmetric Digital Subscriber Lines): operate over existing copper phone lines. (9 Mbps)

Internet Services:

• E-mail: The UUCP mail network began in 1978.
  SMTP (Simple Mail Transfer Protocol): MTA (Mail transfer agent; e.g.: sendmail) and UA (User Agent; e.g.: elm). Note: PC users typically use Pop3 (Post Office Protocol) and IMAP4 (Internet Message Access Protocol) to fetch mail reside in mail servers.
  MIME (Multipurpose Internet Mail Extension): handle images and voice (non-7 bit).

• Usenet news service (1979): Usenet news: over 3000 discussion groups.
  News reader: UNix: tin, nn, and etc. PCs: Netscape/IE's news reader.
  FAQs: http://www.cis.ohio-state.edu/hypertext/faq/usenet/
  Servers: aidebbs.edu.tw, news.csie.nctu.edu.tw and etc.
  

• Domain Name Service (DNS): Allow users to use names rather than IP for hosts on the Net.
  Defined by the Zone: domain, subdomains and those delegated subdomains.
  Static/distributed database

• File Transfer Protocol (FTP): Down/Upload files on the Net.

• Gopher: Distributed information delivery server.(menu driven)

• Veronica: builds the Gopher server index.

  http://galaxy.einet.net/GJ/subject-trees.html
  http://www.cornell.edu/Computer/CUSERVERS.html

• HTTP (Hypertext Transfer Protocol): The Web

  http://www.csie.nctu.edu.tw/
  http://www.bsdi.com/info/becoming-an-isp-kolstad.html

• IRC, Real Audio, CU-SeeMe and MBone

Security

• Encryption:
  DES: Symmetry key (fast)
  Usage: encrypt a message and digital signature; (digital signature: generated by encrypting a msg digest - via a hashing function)
  Public key: Asymmetry key (slow - public and private components) Usage: encrypting a random key and msg digest; (digital envelope: encrypted random key) E.g.: RSA and PGP (free)
• Firewall: is a system or group of systems that control traffic passing between two networks. Conceptually there are two type firewall:
  Application level: FTP, Telnet and SMTP
  Network level: such as traditional router or more sophisticated one like Check Point's FireWall-1 Statefull Inspection Engine.

Future

• Multi user Internet games development
• E-commerce
• Medical applications
• Global low-orbit satellite system: Motorola and Teledesic (Bill Gates and Craig McCaw): 66 satellites v.s. 840 satellites.