Basic Networking

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Basic Networking
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History of the Internet

• 1957 - Soviets launch Sputnik, which leads U.S.
  to create the Advanced Research Projects Agency
  (ARPA)
• 1961 - Leonard Kleinrock Information Flow in
  Large Communication Nets. First paper on
  packet-switching theory
• 1965 - ARPA study on "cooperative network of
  time-sharing computers". Linked with a dedicated
  1200bps phone line!
• 1967 - First design paper on ARPANET
• 1968
• PS-network presented to ARPA
• Begin development of host-level protocols

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History of the Internet

• 1969 - ARPANET commissioned by DoD for research
  into networking
• Node 1 UCLA
• Node 2 Stanford
• Node 3 University of California Santa Barbara
• Node 4 University of Utah
• 1969 - first login (resulted in crash)

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When Things Were Simpler
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History of the Internet

• 1970 - ALOHAnet (first packet-based radio
  network) developed. Connected to ARPANET in '72
• 1971 - 15 Nodes email invented by Tomlinson
  based on SENDMSG
• 1972 -
• the '_at_' sign was chosen by Tomlinson (he modified
  the email program created by ARPANET).
• First email mgmt system 'RD' written
• First computer-to-computer chat
• French try to create CYCLADES
• Telnet specification created (RFC 318)

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History of the Internet

• 1973
• First international connections to University
  College of London
• Bob Metcalf creates Ethernet
• Bob Kahn thinks of gateways
• FTP specification
• Network Voice Protocol enables conference calls
• Study shows email comprises 73 of traffic

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History of the Internet

• 1974 - TCP designed (Cerf and Kahn)
• 1975
• first mailing list
• First satellite link across two oceans (Hawaii
  and UK)
• 1976 - Elizabeth II sends an email
• 1978 - TCP splits into TCP and IP
• 1979
• First MUD
• USENET
• Emoticons first used -) (tongue in cheek)

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History of the Internet

• 1980 - ARPANET grinds to halt because of virus
• 1982 - ARPA establishes Transmission Control
  Protocol (TCP) and Internet Protocol (IP)
• 1983 - Nameserver developed at Univ. Wisconsin
• 1984
• DNS introduced
• Nodes breaks 1000

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History of the Internet

• 1985 - Symbolics.com assigned first registered
  domain. (others were cmu.edu, perdue.edu,
  rice.edu, think.com, css.gov, mitre.org)
• 1987
• Al Gore invents internet (actually helped lobby
  the US research and education network)
• Number of hosts breaks 10,000

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History of the Internet

• 1988 - Internet Worm affects 6000 of the 60,000
  hosts
• IRC developed by Jarkko Oikarinen
• 1989
• hosts break 100,000
• CompuServe and MCIMail first commercial email
  carriers
• 1990
• ARPANET ceases to exist
• First internet dial-up access (world.std.com)

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History of the Internet

• 1991
• Gopher released
• World Wide Web released (Tim Berners-Lee)
• PGP (Pretty good privacy) released by Paul
  Zimmerman
• 1992
• Hosts break 1,000,000
• First audio/video multicast
• "Surfing the Internet" is coined by Jean Polly

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History of the Internet

• 1993
• InterNIC created by NSF
• First internet talk-radio
• Mosaic becomes popular (WWW grows at 341,634
  annually)
• 1994
• Web traffic beats Telnet traffic
• Shopping malls online
• First banner ads on hotwired.com

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History of the Internet

• 1995
• Sun launches Java
• Real Audio
• WWW surpases FTP traffic
• Traditional Online dialup (AOL, CompuServe)
  provide Internet Access
• Netscape becomes popular
• Restrictions of the internet in certain countries
• 2000 - 1 billion indexable pages
• Internet2 backbone network deploys

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Growth

• As of July 2002, there are 162,128,493 hosts.

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Conclusion

• The internet is popular

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So What is It?

• The internet (currently) is simply the physical
  connection between machines.
• Computers
• Cables
• Basic Infrastructure
• The World-Wide-Web is a structure of documents
  that resides on machines connected to the
  internet
• People often confuse the two!

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Network Configurations

• LAN - Local Area Network
• Think Clayton State
• WAN - Wide Area Network
• Think University System of Georgia
• Connects multiple LANs together
• Internet - system of linked networks
• Intranet - a private network often used in
  business
• Ethernet - most popular physical layer
• Others include Token Ring, Fiber, ATM

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Hardware

• Network Interface Cards (NICs) - connect a PC to
  the network
• Hubs - takes incoming signal and repeats it
• Bridge - connects separate networks together
• Switch - examines packets before forwarding
• Router - filter out packets by protocol (or
  ports) instead of packet
• 802.11 - a standard for wireless networking

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Protocols

• Simply a way of how computers identify one
  another on the network (TCP/IP, IPX, AppleTalk,
  etc)
• Also a way of establishing how information will
  be sent
• Usually a handshake
• Then data

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Packets

• Also called "datagram"
• TCP/IP is a "connectionless" technology
• Information is sent in the form of packets
• Header information, such as srcIP and destIP
• Port numbers
• Sequence number
• Checksum
• Number of hops
• Etc..

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TCP/IP

• TCP (Transmission Control Protocol)
• Make sure data gets through to other end
• Rebroadcasts if necessary
• Breaks large data into smaller packets (later)
  and then re-assembles them again
• Make sure everything arrives correctly
• Puts things in order
• Sits on top of IP
• IP (Internet Protocol)
• Provides basic service of getting packets to
  their destination
• Responsible for routing individual packets

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TCP vs UDP

• Two major modes
• TCP a guaranteed protocol (receive ACKs)
• UDP a non-guaranteed protocol (why have it?)
• Simpler protocol than TCP
• Good for small data
• No sequence numbers
• What about UDP mail? A good idea?
• Simpler protocol (ICMP doesn't even contain port
  numbers!)

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Ethernet Level

• Broadcast medium
• When you send data out, all machines on the
  network receive that data
• Ethernet card has a unique MAC address on it
• Only supposed to listen for it's MAC address
• Can "sniff" the network (promiscuous mode) to
  pick up other people's datagrams off the network

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IPs

• Every computer is assigned a unique number
• IPs (AKA addresses) are very similar to URLs in
  structure and meaning.
• Example 168.28.245.183 is an IP
• Notice no http at beginning
• This number directly translates to
  kahuna.clayton.edu
• Use Winipcfg or ipconfig to determine your own IP

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IPs

• Static IPs - you have to pay for these by
  registering
• Networksolutions.com
• Domainit.com
• DHCP - Dynamically allocated IP. This means you
  are granted an IP temporarily!
• Not guaranteed the next time
• Clayton runs on DHCP

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URLsUniform Resource Locators

• Tells us the path to data on the internet.
• Example http//kahuna.clayton.edu/chastine
• http is protocol used (how to send info)
• www. is location also has numbers like
  199.77.144.111
• chastine is a directory where info is kept
• A DNS (Domain Name Server) translates these IPs
  to names and vice-versa
• Unix and nslookup

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Ports

• Several thousand ports/IP
• allows multiple connections on your comp
• Ports 1024 and lower are reserved
• Web Servers (port 80)
• FTP (port 21)
• SSH (secure-shell port 22)
• Telnet (port 23)
• Mail (port 25)
• Gopher (port 70)
• HTTP (port 80)

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The Client/Server Relationship
User 2
Me
kahuna A vault full of important info
You
User 1
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Information Passing

• Requests are made for services

User 2
Me
kahuna A vault full of important info
You
User 1
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Server Side

• Services/information passed back

User 2
Me
kahuna
You
User 1
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Good site

• http//oac3.hsc.uth.tmc.edu/staff/snewton/tcp-tuto
  rial/