Basic Networking

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

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 first login (resulted in crash)

When Things Were Simpler

History of the Internet History of the Internet ALOHAnet (first packet-based radio network) developed. Connected to ARPANET in ' Nodes; invented by Tomlinson based on SENDMSG –the sign was chosen by Tomlinson (he modified the program created by ARPANET). –First mgmt system 'RD' written –First computer-to-computer chat –French try to create CYCLADES –Telnet specification created (RFC 318)

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 comprises 73% of traffic

History of the Internet TCP designed (Cerf and Kahn) 1975 –first mailing list –First satellite link across two oceans (Hawaii and UK) Elizabeth II sends an TCP splits into TCP and IP 1979 –First MUD –USENET –Emoticons first used -) (tongue in cheek)

History of the Internet ARPANET grinds to halt because of virus ARPA establishes Transmission Control Protocol (TCP) and Internet Protocol (IP) Nameserver developed at Univ. Wisconsin 1984 –DNS introduced –Nodes breaks 1000

History of the Internet 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

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

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

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

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 billion indexable pages –Internet2 backbone network deploys

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

Conclusion The internet is popular

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!

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…

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 a standard for wireless networking

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

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..

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

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!)

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

IPs Every computer is assigned a unique number IPs (AKA addresses) are very similar to URLs in structure and meaning. Example: 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

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

URL’s Uniform Resource Locators Tells us the path to data on the internet. Example: –“http” is protocol used (how to send info) –“www….” is location; also has numbers like “ ” –“~chastine” is a directory where info is kept A DNS (Domain Name Server) translates these IPs to names and vice-versa Unix and nslookup

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)

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

Information Passing Requests are made for services kahuna A vault full of important info Me You User 1 User 2

Server Side Services/information passed back kahuna Me You User 1 User 2

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