Transcript Domain name - Computer Science Department

Using the Internet:
Making the Most of the Web’s Resources
Topics
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Internet communications
Online annoyances
How the Internet works
Internet Basics
Origin of the Internet
Future of the Internet
Voice over Internet Protocol
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VoIP - The Internet as a means to place phone calls
Uses technology similar to e-mail to send voice data
digitally
Requires
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a microphone
an Internet connection
A VoIP provider
Services differ
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Free services require an account on both ends
Paid services connect phone to computer
Cable and DSL providers offer phone through broadband
WiFi IP phones call through Internet hotspots and
wireless networks
Wikis
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A wiki is a Web site that allows anyone to
change its content
Wikis provide an excellent source for
collaborative writing
Unlike blogs, wikis can be edited for a
“common” opinion
Edits can be anonymous or named
Be careful of bias in entries
“wiki” is a Hawaiian word for “fast”
First site with wiki in the name set up in 1995
Newsgroups
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Usenet "News"
formed in 1980
Online discussion
forums
Post and reply to
messages publicly
Need a feed from
a news server most ISPs have
one
E-mail
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fast,
convenient,
cheap
asynchronous
E-mail accounts
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Client-based
Web-based
Forwarding
(image from Wikipedia "How
Email Works")
Mailing lists
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"Listservs"
people must subscribe
messages sent by email
sent only to people who subscribe,
not general public
do NOT use the "Reply All" option
unless you mean to!
Social Networking
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MySpace, FaceBook
easy, cheap
danger of identity theft
danger of revealing information
which can be harmful later
danger of sexual predators
E-commerce
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buying, selling, advertising, banking
look for secure "signed" sites
https:// versus http://
check with Better Business before
buying
use credit card for purchase
Online Annoyances
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Spam – electronic junk mail
Pop-ups – intrusive advertising
Cookies – tracking user’s browsing
habits
Malware - software that has a
malicious intent - spyware, viruses,
Trojans, worms, etc.
Phishing and Hoaxes – Ruses to fool
and maybe steal from users
Spam
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Junk e-Mail
May soon comprise 90%
of email volume
Named after a Monty Python sketch Link
Antispam practices
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Don’t reply to it, even to “unsubscribe”!
Use “dummy” addresses – can get free ones
Read privacy statement on a site before you
give them your address
Spam filters
Pop-ups
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Usually advertising
Pop-up
automatically
Can also contain
spyware
Most browsers can
prevent them
Pop-up blockers
Cookies
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Text files stored on
client computers
when visiting Web
sites
Used on return visits
to Web sites
Unique ID number
Personal information
remembered
Privacy risk
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Selling information
Spyware
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Added as a program
piggybacked with a
requested program
Secretly gathers
information, usually
about surfing habits
Antivirus software
doesn’t detect it
Spyware removal
programs are
required
Spyware
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Very often comes in from file-sharing,
P2P sites
Ties up system resources, can modify
browser settings, can spawn popups
and other ads
Read the EULA for any software you
install before you install!
Run Ad-Aware to clean it up
Phishing and Hoaxes
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Phishing is a phony
communication from a
trusted source
Phishing attempts to
scam someone into
sending vital
information
Hoaxes are attempts to
scam people into
sending money, or join a
chain letter
Malware
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Software that has a malicious intent
Spyware is a form of malware
Other forms are viruses, worms,
and Trojan horses
Designed to render a computer
useless or control it completely
How the Internet works
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Domain Names
URLs
Navigating the Web
Domain Names
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Easy-to-remember names for Internet
servers
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Every domain name corresponds to a
unique IP address
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Ends with an extension that indicates its toplevel domain
Domain Name System
cybersquatting
ICANN coordinates technical management
of the Internet’s Domain Name System
Domain Names
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Most specific information on the
LEFT
Top Level Domain Names
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.gov .com .edu .net
Subnets and Sub Domains
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uky.edu
cs.uky.edu
www.cs.uky.edu
ftp.cs.uky.edu
Current Top-Level Domains
.aero
industry
.biz
.com
.coop
.edu
.gov
.info
.mil
.museum
.name
.net
.org
.pro
Members of the air transport
Businesses
Can be used by anyone
Cooperative associations
Degree granting institutions
United States government
Information service providers
United States military
Museums
Individuals
Networking organizations
Organizations (often nonprofits)
Credentialed professionals
Top Level Domains - Country
Codes
URL
Uniform Resource Locator
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Unique Internet address
Protocol could be http, mailto, ftp, news,
…
 NOTE difference between http and https
Path
Domain name
identifies the
contains the
subdirectories
host and topwithin the
level domain
Web site
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Protocol
identifies
the means
of access
URL http:// www.nytimes.com/ Pages/cartoons/
Navigating the Web: Web Browsers
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Software running
locally on your
machine
Graphical
Enables Web
navigation
Popular browsers:
 Internet Explorer
 Firefox
 Camino (Mac OSX)
Web Sites
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Web site:
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Collection of related Web pages
First page known as Home or Index
page
Web pages:
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HTML documents
Hyperlinks
Related
pages
The Internet and Copyright
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All original material on the Net is
copyrighted, © or not
Copyright is violated when you get
economic benefit from using the
material
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Exception of "academic fair use"
Plagiarism is different from
copyright violation – it is presenting
someone else's work as your own
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Credit your sources!
Search Engines
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“Spider” or “Web
Crawler” program scans
Web pages
Information found is
entered in their
database
User enters keyword or
phrase in search box in
browser
Results (hits) are sent
to the client software
and displayed
Evaluating Web Sites
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Who is the author of the article or
Web site sponsor?
What audience is the site geared
toward?
Is the site biased?
Is the information current?
Are links available?
Who is hosting? Is it a .gov site?
.edu? .com?
File-sharing - P2P networks
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Files traded from machine to
machine - broadband
Majority of files are copyrighted and
permission has not been given for
the copying
Risks
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Legal problems
Malware in both the software and the
files
Software Copyrights and Licenses
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Different types of software licenses
where the money come from?
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Commercial software -from sale of licenses
Shareware - from registrations and ads
Freeware - from advertising and spyware
Open source - free labor of volunteers and
donations
Public domain - donations from community
The Internet: The Basics
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Protocols
IP numbers
Clients and servers
Connecting to the Internet
Origin of the Internet
The Internet vs. the Web
Internet Protocols
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TCP and IP serve as the primary
protocols responsible for message
transmission on the Internet
Internet Protocol
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Messages are divided into small
pieces called packets
These are labeled with the IP
numbers of the machine they came
from and the one they are going to,
and a order number ( like 1 of 5)
The protocol says how to route
them to get to the destination
Not all packets take the same route!
IP Addresses
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IP addresses are addresses that
identify computers on the Internet
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Static IP address
Dynamic IP address
IP Addresses
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IP addresses have the problem in
TCP/IP of running out
Internet 2 consortium designing
new protocols that fix the problem
Dynamic IP numbers – short term
fix
Client and Server
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Client computer:
 Users connect to the Internet
 Request data and Web pages
Server computers:
 Store Web pages and data
 Return the requested data to the client
Client
Server
Connecting to the Internet
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Dial-up connection:
 Uses standard
telephone line
 Least costly
connection
 Requires a modem
 Converts analog
to digital and
vice versa
 Slowest connection
speed (56Kbps)
Broadband Connections
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Digital Subscriber Lines
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Faster than dial-up
Upload (300Kbps – 1.5Mbps)
 Download (1Mbps – 1.5Mbps)
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Requires special DSL modem
Symmetrical
or Asymmetrical
DSL
modem
Broadband Connections
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Cable:
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Uses TV coaxial
cable
Fast connection
speed (500Kbps –
4Mbps)
Speed depends on
number of users
Not available in all
areas
Requires a cable
modem
Coaxial
cable
Satellite Connections
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Uses a satellite
dish and coaxial
cable
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Download speed
500 kbps
Upload speed 100
kbps
Signal is affected
by location and
weather
Comparing Internet Connection Options
Connectio
n Option
Maximum Upload Data
Transfer Rate
(approximate)
Maximum Download Data
Transfer Rate (approximate)
Dial-Up
56 Kbps
56 Kbps
DSL
(ADSL)
300 Kbps
1 Mbps
DSL
(SDSL)
1.5 Mbps
1.5 Mbps
Cable
500 Kbps
4 Mbps
Satellite
100 Kbps
500 Kbps
Choosing an ISP
Factors to consider:
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Cost
Local access numbers
Services Offered – email, web page
hosting, news reading
Reliability
Speed
Support and Customer Service
ISP Infrastructure
The Origin of the Internet
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ARPANET:
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Advanced Research Projects Agency Network
Funded by the U.S. government in the 1960s, lasts until 90's
Allowed computers at leading universities and research
organizations to communicate with each other over great
distances
First Working Version of the Packet Switching Network
NSFNet – National Science
Foundation Network
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Connecting 5 supercomputers and the researchers
using them, 1986
commercialization of the Internet - late 80's
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NSF stops funding the Net - 1994
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Internet Structure
The Web
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The Web is a part of the Internet
distinguished by:
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common communication protocols TCP/IP and
HTML
special links (called hyperlinks)
Web invented in 1989 by Tim Berners-Lee
1993, National Center for
Supercomputing Applications (NSF)
releases the Mosaic browser
Developers of Mosaic release Netscape
(1994)
The Internet vs. The Web
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Internet – part of the system that is primarily
hardware infrastructure (telecommunications,
routers, servers, disk drives, etcetera)
Web – part of the system that contains
intellectual property in many formats (text files,
graphic files, sound files, video files, etc.)
The Internet existed before the WWW interface –
people used command line programs
Future of the Internet
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Large Scale Networking
(LSN):
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Research and
development of cuttingedge networking and
wireless technologies
Internet2:
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Project sponsored by
universities,
government, and
industry to develop new
Internet technologies
Internet2 backbone
supports transmission
speeds of 9.6 Gbps
Internet Access Security
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"always on" is security risk - turn
the computer off!
keep OS and anti-virus software up
to date
USE firewall software
browser security settings
for LAN, use NAT - router Network
Address Translation
virtual private network (VPN)
Issue: Free Wi-Fi access
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Some people offer wireless access
for free to the community
A good point - people who can't
afford to pay for it can use it
Broadband providers don't like
people giving it away for free
A bad point - can be used for illegal
activities