Part 1 - Personal Psu

nervousripSecurity

Nov 5, 2013 (4 years and 2 days ago)

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Internet Infrastructure

Min Ding

Smeal College of Business Administration

Pennsylvania State University

The Future of Computers


"I think there is a world market for maybe five
computers."
--
Thomas Watson, chairman of IBM, 1943


"Computers in the future may weigh no more than 1.5
tons."
--
Popular Mechanics, 1949


"But what ... is it good for?"
--
Engineer at the Advanced
Computing Systems Division of IBM, 1968, commenting
on the microchip.


"There is no reason anyone would want a computer in
their home."
--
Ken Olson, president, chairman and
founder of Digital Equipment Corp., 1977


"640K ought to be enough for anybody."
--

Bill Gates,
1981

Today’s Topics


Internet Communication
--

Internet
Protocol Suite


Web Technology


building blocks of e
-
commerce


What does it take to have your own web
server?

Internet Protocol Suite


Communication among computers is
achieved by following a set of
agreements (or protocols);


Each protocol suite has multiple layers;


TCP/IP is the most widely implemented
protocol suite in use.

Layers of TCP/IP suite


Application layer (e.g., HTTP)


Transport layer (e.g., TCP)


Network layer (IP)


Physical layer (e.g., Ethernet)

Physical layers


Internet is a network of many different
networks
--

LAN (e.g., Ethernet, token ring)
and WAN (e.g., dialup, frame relay, point
-
to
-
point circuits);


Internet routers are used to connect these
networks;


Routing protocols determine how information
(packet) are forwarded;


Routers are often used as first line of defense
against network attack.

Network layer


Network layer takes care of IP address
and domain name service (DNS)


IP provides both packet (data) addressing
and best
-
effort forwarding services (kind
of like mailroom);


IP layer assigns a uniform address
structure (32 bit address) to each
computer connected to the network.


IP address, e.g., 255.255.255.255

Network layer (continued)


Domain Name Systems (DNS) offers
easily readable names for IP addresses





IP address and DNS name do not
always correspond to each other.

Transport Layer


Unreliable Datagram Protocol (UDP)



Transmission Control Protocol (TCP)

Application layer

Application protocols, include


FTP


HTTP


Telnet



Building blocks of e
-
commerce
(WWW technology)


Protocols


Browsers


Servers


Application development structures
(e.g., Java, Active X, CGI)

World Wide Web

You mean web is not the same as internet?


Web is only a part of internet mainly
based on one type of application
protocol, namely, HTTP.


HTTP:

hypertext transfer protocol

WWW browsers


Netscape Navigator, Microsoft Internet Explorer


Web browsers include built
-
in support for HTML
(hypertext markup language) and


MIME (multimedia internet mail extensions), e.g., image/gif,
video/mpeg


Plug
-
ins (added application to help browser display new data
type);


Scripting (permit executable scripts to be embedded in web
pages, e.g., JavaScript or VBScript);


Applets (written in Java, downloaded on demand from server)


ActiveX controls (used by Internet Explorer), similar to Java
applets, but has free control of the computer.


Takeaway:

Potential customers using less advanced



browsers may not be able to access all your features..

Web Servers


AOLserver (free)


Apache, most popular web server (free)


Microsoft IIS(internet information
server)/ASP(active server pages)

Server


API (application programming interface)


CGI(the common gateway interface)


Server
-
side scripting


Server
-
side includes (simple)


Server
-
side scripting (Java, JavaScript, VBScript),
Microsoft’s ASP is an execution environment for
server scripts and control.


Database
-
driven templates


Similar to server scripting

Uniform Resource Locators (URLs)

http://assets.wharton.upenn.edu/~min42


http://





protocol designator

assets.wharton.upenn.edu


server name

~min42




pathname to resource

Web content transport


Pull


information is retrieved by the
client browser


Push


user signs up for a channel of
content and relevant information is
automatically delivered to the desktop

Anybody can do it…

Source: http://www.nysaes.cornell.edu/comm/staff/zakour

Three levels of web hosting


Part of somebody else’s machine

assets.wharton.upenn.edu/~min42

www.planetding.com

(virtual hosting)


My machine in other people’s network

e.g., Exodus


My machine, my network


Choosing a computer


Unix


Run Linux on PC


Windows NT

Connect to the internet


ISDN (integrated services digital network),
128k point to point connection from the phone
company


Cable modems (AtHome, can’t be used as
server in this area), around 1 Mbps


ADSL(asymmetrical digital subscriber line), up
to 6 Mbps


T1:

1.5 Mbps dedicated connection to
somebody’s backbone network
($2000/month);


T3:

45 Mbps ($50,000/month)

Take Home Message

(translation: things to remember for final exam)


The concept of protocol suite, and
TCP/IP.


Understand the roles of browser and
servers.


What do you need to do to set up your
own web server?