Transcript Chap 8 The Internet - California State University, Sacramento

Chap 8 The Internet
• How the Internet works, the short answer
• What does the internet offer?
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Online services and ISP
The World Wide Web and Hypertext Transfer Protocol
E-mail
FTP – File Transfer Protocol
Newsgroup
Chatting, Instant Message and Internet Relay Chat
Telephony
Virtual Networks and other Connections
Accessing the Internet
with Windows XP
Accessing the Internet
with Windows XP
This lesson will cover:
• The definition of the Internet
• The “Web”
• E-Mail
• Newsgroups
• Internet Tools
• Web Browsers
• Search Engines
• FTP
• Using Internet Explorer
What is the Internet?
The Internet is a worldwide computer network. It is a network
of networks. There is no central control, all the computers and
sub-networks are linked together on a voluntary basis.
These computers use the TCP/IP (Transmission Control
Protocol/Internet Protocol) as the method of connecting to each
other and transferring information. TCP/IP is a “suite” of
software programs that ensure traffic flows freely and efficiently
on the ‘net.
Before we really get started with the details you may want to go over a
Glossary of Internet and Web Jargon courtesy of the UC Berkeley
Library…
More…What is the Internet?
In 1969 four host computers were connected together to form ARPANET,
this would later become the Internet as we know it. The first connections
were between:
•Stanford Research Institute
•University of California Los Angeles
•University of California Santa Barbara
•University of Utah
Although this project was highly motivated by the US Department of
Defense, several separate networks were created by the Department of
Energy, NASA and the National Science Foundation. These networks
were unconnected…for a while…
Click this link for a A Brief History of the Internet courtesy of the The
Internet SOCiety (ISOC)…
More…What is the Internet?
…ARPANET grew into the Internet by connecting to other
networks as technology advanced. The development of
networking protocols like TCP/IP and Ethernet allowed
greater connectability of diverse systems.
Finally the growth of Local Area Networks (LAN) and the
widespread use of PCs forced new growth, until in 1996 there
were over 50,000 networks interconnected on the Internet.
Originally the main concern of the Department of Defense
was the “survivability” of the network, could it withstand a
major attack and still operate effectively.
More…What is the Internet?
The "internetwork" in Theory
redundant connections...
More…What is the Internet?
The "internetwork" in Theory
redundant connections...
mean no central control.
More…What is the Internet?
LAN sends a request out on the Internet to a "remote" network...
LAN
Router
Remote LAN
Router
Telecom
Connection
Firewall
LAN Server
Router
Telecom
Connection
How the Internet Works, the short
answer
• Because the internet is a network, each computer must have a unique
address just like any node on a network.
• Every Computer has an IP address, that is unique; for example the IP
address of CSUS.edu is 130.86.90.1
• When the request is issued it first goes to a server that determines the
address of the remote server and then it goes to a router that “routes” it to
the destination. The routing can include visits to other routers that will
reroute the request according to the current traffic and “state” of the
Internet.
• With Visual Route you can see the routers implicated and their place in the
world
What does the Internet Offer?
Servers on the Internet can provide the following services to
the users that logon to them:
• FTP - The File Transfer Protocol is an efficient way to send or receive
files from another computer.
• E-mail - Provides electronic mail services which include mailing lists
(listservs®) and discussion groups.
• Newsgroups - These are organized “discussion” forums, sometimes
called USENET, and are very narrowly classified by subject, such as
rec.photo.equipment.35mm, or microsoft.public.windowsxp.general.
• World Wide Web - Servers that use the HTTP to exchange files are
part of the largest group users on the Internet. These computers “serve”
HTML files, which are rendered as “web” pages on the users local
computer.
Online services and Internet
Service Providers
An internet Service Provider (ISP) is a business that provides its
clients an access to the internet through a Point of Presence (POP).
Dial-up connection

The Internet
ISP
Point of Presence
(POP)
POP
NAP
Network Access
Point (NAP)
LAN using a leased line (T1)
connection to the POP
Main ISP
• AOL :
Leader of the market , 30 million subscribers
Services: chat rooms, Shopping, AOL instant messenger,
Internet Email, DSL Communication
• CompuServe : Initially directed toward large companies
Bought in 1997 by AOL.
• Prodigy : Developed by IBM an Sear in 1984.
Propriety of SBC Communication
3.5 million customers
• MSN :
Newcomer on the market
Presence under the Name Microsoft Network
The world wide web –Hyper Text
Transfer Protocol
The World Wide Web is a collection of computers
connected via the Internet that support the use of documents
written in HyperText Markup Language (HTML).
The “web” uses the HyperText Transfer Protocol (HTTP)
as the standard for the formatting and transmission of these
documents.
Not every server on the ‘net uses HTTP, and therefore is
not part of the Web.
The Web
Since the World Wide Web
supports documents that are formatted using HTML, you
need to use a special application known as a “Web Browser”
to open and view them. Most modern browsers also include
the capability to “play” multimedia files such as video and
audio. Retrieving files via FTP and accessing e-mail servers
is another feature that has been added, but are really not web
functions.
The browser works by downloading (or retrieving from the
remote server) a file and then rendering it according to the
HTML specifications…
E-mail
• E-mail (or Electronic Mail) refers to the transmission of
messages over computer network.
• Although most browser includes e-mail capabilities, many
people still rely on single purpose mail programs, like Pine,
Eudora and Outlook.
• Most Internet e-mail is sent from mail clients to mail servers
using th Single Mail Transfer Protocol (SMTP).
• Webmail account is e-mail that can be accessed without having
an account with an ISP, like Hotmail or Yahoo!mail.
FTP…Internet File Transfers
The File Transfer Protocol is simply the protocol used on the Internet for
sending files from one computer to another. It can be as “simple” as the
command line program that comes with Windows 2000…
The command ftp starts the program,
and help displays help…transferring
files like this takes a bit of skill
because you need to access remote
computers and navigate through
their file systems, and it is all done
by typing in commands like ls for a
directory listing…
Entering the command “bye” closes the session…
…or you can…
WS_FTP…
WS_FTP is a Windows program that takes the work out of sending and
receiving files on the Internet…this program can be used for free by students
and is available from ZDNet…click the “About WS_FTP” window below to
go to the download site…the next 2 slides show a few of the features of
WS_FTP Limited Edition (the free version)…
WS_FTP…
Enter the address of the host you want to open a session with…the user name
anonymous is a universal id that will gain access to many “public” computers.
With an anonymous login you need only use a “dummy” password…many
systems ask for your e-mail address, but you need not use your real one…
WS_FTP…
You are now browsing the /pub directory of the host computer cdrom.com
Transferring files is now as easy as highlighting the filename(s) and clicking
the appropriate arrow…the left arrow moves a file from the right pane (the
remote computer) to the left pane (your computer)…and visa versa.
Internet Newsgroups
An Internet newsgroup is a specific type of online forum or
discussion group. Newsgroups use a different application level
protocol, the Network News Transfer Protocol, or NNTP to
deliver its data to users. These groups are sometimes called
USENET. They are like private e-mail lists that maintain the emails or “posted” messages in the order that they were sent and
answered. This arrangement is called message threading.
By using a newsgroup you can follow the messages of others,
which is called lurking; or you can participate in the action by
posting questions, comments or answers to other messages.
Internet Newsgroups
Newsgroups are an excellent way to connect with people that
have the same interests, hobbies and problems. They are good
for getting answers to technical questions on many subjects, as
they generally deal with very narrow subjects.
When using a newsgroup you should be careful about posting
your e-mail address (or any contact information for that
matter)…in fact, many people use a phony address like
[email protected]. This is because spammers also lurk
among the newsgroups looking for addresses that they can use
or sell.
Internet Newsgroups
Newsgroups are accessed on the Internet by using a program
called a newsreader. Most modern browsers include news
reading capabilities in their software.
The following slide shows Microsoft’s Internet Explorer 6 in its
newsreading mode. There are, however, many more single
purpose readers that incorporate added features, including
enhanced security.
Use this link to see a large list of newsreader programs on
CNET.
Using Internet Explorer 6 to “read” Newsgroups
The listing of
posted messages
The current
Newsgroup
…and the
number of
messages
posted to it.
The text of
the selected
“post”…
Chatting
• Chat rooms as offered by service providers such as AOL
are not features of the internet.
• They exist only within the boundaries of the service
provider, only subscriber of that provider can access them.
• Chat room provide real time contact between users
Instant Messaging and Internet
Relay Chat (IRC)
The original IRC network is EFNET
(Eris Free).
Instant messaging (IM) allows a real time
discussion between two specific users.
Two different users have to use the
same software to converse.
The most popular IM software are
AOL Instant messenger and
the MSN Messenger.
Telephony
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Internet Telephony is a segment of
internet technology that combines
capabilities of a telephone system,
such as voice communication and fax
transmission, with Internet protocols.
This idea promises low costs on long
distances.
Companies providing such services
are Net2phone, ICQphone and
NetMetting