Transcript Networking Fundamentals - Part 2 CS 1 Rick Graziani Cabrillo College ISP Internet Service Provider 24.205.224.36 IP Address = Sub Mask = Default Gateway = Default Gateway 75.140.156.1 Rick Graziani [email protected] DNS Server =

Networking Fundamentals - Part 2
CS 1
Rick Graziani
Cabrillo College
ISP
Internet
Service
Provider
24.205.224.36
IP Address =
Sub Mask =
Default Gateway =
Default
Gateway
75.140.156.1
Rick Graziani [email protected]
DNS Server =
ISP
Internet
Service
Provider
24.205.224.36
DHCP
IP Address =
75.140.157.97 (Public)
Sub Mask =
255.255.255.252
Default Gateway =
75.140.156.1
Default
Gateway
75.140.156.1
Rick Graziani [email protected]
DNS Server =
24.205.224.36
DSL/Cable Modem
Rick Graziani [email protected]
Router
4
Rick Graziani [email protected]
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Rick Graziani [email protected]
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Rick Graziani [email protected]
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ISP
Internet
Service
Provider
IP Address =
Sub Mask =
Default Gateway =
24.205.224.36
DNS Server =
IP Address =
Default
Gateway
75.140.156.1
Sub Mask =
Default Gateway =
DNS Server =
Public IP
Address
75.140.157.97
Router/Default Gateway
Default Gateway: 192.168.1.1
DHCP Server:
Network = 192.168.1.0 (Private)
Sub Mask = 255.255.255.0
First host: 192.168.1.100
Rick Graziani [email protected]
Network Address Translation
75.140.157.97  192.168.1.host
IP Address =
Sub Mask =
Default Gateway =
DNS Server =
8
ISP
Internet
Service
Provider
IP Address =
192.168.1.100
Sub Mask =
255.255.255.0
Default Gateway =
192.168.1.1
24.205.224.36
DNS Server =
24.205.224.36
Default
Gateway
75.140.156.1
DHCP
IP Address =
192.168.1.101
Sub Mask =
255.255.255.0
Default Gateway =
192.168.1.1
DNS Server =
Public IP
Address
75.140.157.97
24.205.224.36
Router/Default Gateway
Default Gateway: 192.168.1.1
DHCP Server:
Network = 192.168.1.0
Sub Mask = 255.255.255.0
First host: 192.168.1.100
Rick Graziani [email protected]
Network Address Translation
75.140.157.97  192.168.1.host
IP Address =
192.168.1.102
Sub Mask =
255.255.255.0
Default Gateway =
192.168.1.1
DNS Server =
24.205.224.36
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Rick Graziani [email protected]
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Rick Graziani [email protected]
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IP Address =
192.168.1.100
I need an IP address
www.bayfed.com
Sub Mask =
255.255.255.0
Default Gateway =
192.168.1.1
24.205.224.36
www.bayfed.com is at
65.64.172.199
ISP
Internet
Service
Provider
DNS Server =
24.205.224.36
Default
Gateway
75.140.156.1
Public IP
Address
75.140.157.97
Bay Federal
65.74.172.199
Rick Graziani [email protected]
Router/Default Gateway
IP Address =
192.168.1.100
Sub Mask =
255.255.255.0
Default Gateway =
192.168.1.1
24.205.224.36
DNS Server =
85.255.112.1
ISP
Internet
Service
Provider
Default
Gateway
75.140.156.1
I need an IP address
www.bayfed.com
Public IP
Address
75.140.157.97
Bay Federal
65.74.172.199
Router/Default Gateway
85.255.112.1
85.255.112.99
Rick Graziani [email protected]
www.bayfed.com is at
85.255.112.99
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1981 primitive Internet report on KRON
http://www.youtube.com/watch?v=5WCTn4FljUQ&feature=pl
ayer_embedded
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Circuit Switched
• Circuit Switching: A form of data communication which establishes a
•
•
single connection or circuit between source and destination to carry the
data stream.
Like a conventional telephone system.
When a subscriber makes a telephone call the dialed number is used
to set switches in the exchanges along the route of the call so that
there is a continuous circuit from the originating caller to that of the
called party.
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Packet Switching
• Packet Switching: A form of data communications which breaks
•
a data stream into small sections, sends them separately by the
best available channels and reassembles the original data
stream at its destination.
An alternative is to allocate the capacity to the traffic only when it
is needed, and share the available capacity between many
users.
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Wireless Access Point
•
A wireless access point is a device that connects
wireless devices (laptops, etc.) to a wired network, usually
an Ethernet LAN.
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Wireless Access Point
•
In our example the wireless access point (AP) will include a
Router.
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Putting it together
•
Exactly the same as connecting a router without an AP.
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Configuring the AP and Router
Wireless Settings:
• SSID (Service Set Identifier) – Name of your network
• Security: WPA2, WPA, WEP, or none
SSID
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Configuring the AP and Router
Wireless Settings:
• Security: WPA2, WPA, WEP, or none
WPA2
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SSID
•
The SSID is what will be displayed when people with
wireless computers are looking for a wireless LAN.
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Linksys WRT54G
Router Information
• IP Address from ISP
• Connects to your DSL/Cable Modem
• NAT (Network Address Translation)
Local Network
• Ethernet Switch
• Connect “wired” computers
• DHCP Server (optional)
Wireless
• SSID: MyHomeNetwork
• DHCP Server: (optional)
• Channel: 11
• Encryption Function: WPA
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You choose…
•
•
•
•
There are many resources to discuss the possible health
risks or wireless LANs.
As a networking and WLAN user and instructor I have my
own thoughts which I will share.
If you are concerned, then research the information and
come to your own conclusions.
The following information is from my own research and
experience.
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Wireless Frequency
• Wireless APs operate at:
•
•
– 2.4 GHz
– 5 GHz
2 GHZ! That’s the same as my microwave oven, isn’t that dangerous?
Answer: No.
– Electromagnetic waves happen naturally.
• Light is an electromagnetic wave
– It is not the frequency, but the wattage, the power.
• Any electromagnetic wave can be dangerous with too much
power.
• A 25 watt light bulb is safe, but it wouldn’t be safe at 250,000
watts
– Wireless access points generate signals at 1/10th of a watt.
• Like all electromagnetic waves, the signal does not fade in a
linear manner, but inversely as the square of the distance.
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Rick Graziani [email protected]
www.britishlibrary.net
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Inverse square law
10
Point A
20
30
40
3 times the distance
1/9 the power of Point A
2 times the distance
¼ the power of Point A
50
100
10 times the distance
1/100 the power of A
5 times the distance
1/25 the power of Point A
• Double the distance of the wireless link, we receive only ¼ of the
•
•
original power.
Triple the distance of the wireless link, we receive only 1/9 the original
power.
Move 5 times the distance, signal decreases by 1/25.
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Putting it in some perspective
• Measurements from an antenna transmitting 100mW at 1 inch
• Remember a milliwatt is 1/1,000th of a Watt
• Microwave oven typically operates at 1,000 watts in a confined space.
•
•
1”
100 mW
1/10th watt
2”
25 mW
1/40th watt
4”
6.25 mW
1/166th watt
8”
1.56 mW
1/1000th watt
16”
0.39 mW
4/10,000th watt
32”
0.097 mW
1/10,000th watt
64” (5.3 ft)
0.024 mW
2/100,000th watt
128” (10.6 ft)
0.006 mW
6/1,000,000th watt
256” (21.3 ft)
0.0015 mW
15/10,000,000th watt
Light bulbs would also be dangerous the were 10,000 to
1,000,000,000,000 stronger.
A 250,000 watt up to a 250,000,000,000,000 watt light bulb would also
be dangerous.
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Wireless N
•
•
Wireless N provides better speeds (bandwidth) and better
range by utilizing multiple antennas.
Backwards compatible with 802.11 b and g.
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Wireless Security – Everyone can hear
•
•
Others can “hear” or capture your information.
Wireless signals are propagated, sent, similar to our voice
sound waves.
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Wireless Security – Everyone can hear
• If we don’t want them to understand what they hear, we can encrypt or
•
code the information.
As long a our wireless computer and access point are using the same
encryption algorithm, such as WEP or WPA.
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Wireless Security
•
Without any security, anyone can:
– Use your wireless access point to access your network
and the Internet.
– Capture your information from your wireless computer.
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Wireless Security
CommView
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DriftNet
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Wireless Security
• Your web browsing or email access should already be secured.
• Look for the lock
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Wireless Security
•
•
Why you should protect your wireless network with WPA
– http://www.youtube.com/watch?v=A88XB7_Jz7s
Wireless Hacking
– http://www.youtube.com/watch?v=qP1BOZqrp5g&featur
e=related
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MAC Cloning
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Cell Phones do not cause explosions
• http://www.youtube.com/watch?v=OQ0aTMMITp8
• http://www.youtube.com/watch?v=NRGrFLRs9xE&feature=
related
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Careers in Information Technology
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Computer Support Specialist
•
•
•
Installing computer hardware
and software.
Troubleshooting
Maintenance and upgrades
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Networking: System Administrator
• Installing, configuring, and maintaining network servers
• UNIX, LINUX, Microsoft
• Web, DNS, DHCP, Mail Servers
• Backup and recovery, user administration
• Security
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Networking: Network Technician/Analyst
• Install, manage, troubleshoot network infrastructure:
•
– Routers, Switches, Cables, Wireless Access Points
Issues: Security, Quality of Service, Video On Demand,
Voice over IP
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Keeping up on technology
• Wireless
• Security
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Internet: Safe Surfing
Safe Surfing
• Adware
•
•
•
•
•
– Pop-ups
– Spyware
– Blocking Pop-ups
Java Traps or Pop-Up Hell
Spyware
– Blocking Spyware
Cookies
Virus Protection
Spam
– Blocking Spam
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Adware
• Adware or advertising-supported software is any software application
•
in which advertisements are displayed while the program is running.
Adware helps recover programming development costs, and helps to
hold down the price of the application for the user (even making it free
of charge)—and, of course, it can give programmers a profit, which
helps to motivate them to write, maintain, and upgrade valuable
software.
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What are Pop-ups? (Wikipedia.org)
• Pop-up ads are a form of online advertising on the Web where certain
•
•
websites open a new web browser window to display advertisements.
Usually generated by JavaScript
A less intrusive variation on the pop-up window is the pop-under
advertisement.
– This opens a new browser window, but in the background, so as
not to interrupt the user's page-view.
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From Gain Publishing:
www.gainpublishing.com/ about/
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•
•
•
•
For early advertising-supported websites, banner ads were sufficient revenue
generators.
But in the wake of the dot com crash, prices paid for banner advertising
clickthroughs decreased and many vendors began to investigate more
effective advertising methods.
Pop-up ads by their nature are difficult to ignore or overlook, and are claimed
to be more effective than static banner ads.
Pop-ups have a much higher click rate than web banner ads do.
– What are Pop-ups? (Wikipedia.org)
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What are Pop-ups? (Wikipedia.org)
Ultimate
irony!
•
•
Most users regard pop-ups as a nuisance.
In the early 2000s, all major web browsers except Internet
Explorer allowed the user to block pop-ups almost
completely.
• In 2004, Microsoft released Windows XP SP2, which
added pop-up blocking to Internet Explorer.
• Many of the latest pop-ups are created using Flash and
have extensive animation and trickery.
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Pop-up, looks real…
http://www.news3insider.com/finance/google-hiring-you.html
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Block Pop-up Windows with Internet
Explorer
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C/NET – Pop-ups mean more $$$
• Publishers willingly allow pop-ups or pop-unders
because they command higher prices, and they're
in high demand by advertisers.
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“Java Trap” or
“Pop-up Hell”
• Pornographic websites are among the most common users of pop-up
•
•
•
•
ads.
Some particularly vicious types of pop-up ads have been specifically
designed to "hijack" a user's Internet session.
As each window is closed by the user it activates another window -sometimes indefinitely.
Usually the only way to stop this is to close the browser.
Mouse Trapping: Another variation of pop-up fills an entire screen
with an ad or Web page, removing any menu bars or other on-screen
icons by which the user can close the window.
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Spyware (Wikipedia.org)
• Spyware is computer software that gathers and reports information
•
•
about a computer user without the user's knowledge or consent.
May perform many different functions, including:
– Delivery of unrequested advertising (pop-up ads in particular),
– Harvesting private information
– Re-routing page requests to illegally claim commercial site referral
fees
Spyware or Malware Can include:
– keystroke loggers
– denial-of-service (DoS) attack agents
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Fighting Spyware
• Spybot (www.safer-networking.org)
• PestPatrol (www.pestpatrol.com)
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Cookies
• A cookie is information sent by a
•
•
server to a browser and then sent
back to the server each time it
accesses that server.
Amongst other uses, cookies
enable websites to be customized
for individual users once
browsing patterns have been
established.
Cookies only store information
that you provide.
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First time you login
HTTP Requests: GET
(first time)
HTTP: Response
Set-cookie: ID
5551212
HTTP Requests (GET)
Web server can now
now include ID track clients activities
5551212
on the web site.
HTTP
Server
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HTTP Client
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Each time you login…
HTTP: Cookie 5551212 included
HTTP
Server
HTTP data customized
for Rick Graziani
HTTP Client
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Cookies - Purpose
• Typically this is used to authenticate or identify a registered user of a
•
web site as part of their first login process or initial site registration
without requiring them to sign in again every time they access that site.
Other uses are maintaining a "shopping basket" of goods selected for
purchase during a session at a site, site personalization (presenting
different pages to different users), and tracking a particular user's
access to a site.
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Cookies - Permissions
• A browser may or may not allow the use of cookies.
• The user can usually choose a setting.
• Microsoft Internet Explorer
– Tools > Internet Options > Privacy Tab
– Use slider to set options, or use advanced options
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Virus Protection
•
In computer security technology, a virus is a selfreplicating program that spreads by inserting copies of
itself into other executable code or documents
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http://techguylabs.com/
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Be careful when opening attachments!
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•
“According to folks working on the case who talked to us at the HTCIA
HighTech Crime Investigation Association international training this fall, the
major method used by the Chinese hackers was to identify Google workers
through their Facebook pages, trace back through their home town /
highschool information, get the yearbook, make fake email / facebook accounts
in the names of others from the yearbook, and make friends with the Google
workers on the net. Eventually they sent them malware in photos which gave
Chinese
the entry into the Google work systems.”
Rick the
Graziani
[email protected]
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Computer Virus, Spyware
•
•
Computer Virus, Spyware
http://www.youtube.com/watch?v=uK5ija2gVbY
•
•
How Computer Viruses Work
http://www.youtube.com/watch?v=sxal31zIKdE&feature=rel
ated
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May 4th,
2009
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Spam (Wikipedia)
•
Spamming is the act of sending unsolicited electronic
messages in bulk.
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Anti-Spam
• Spammers obtain e-mail addresses by a number of means:
•
•
•
– Web pages
– guessing common names at known domains
– "e-pending"
– searching for e-mail addresses corresponding to specific persons
Many e-mail spammers go to great lengths to conceal the origin of their
messages.
Spoofing e-mail addresses - spammer modifies the e-mail message
so it looks like it is coming from another e-mail address.
Among the tricks used by spammers to try to circumvent the filters is to
intentionally misspell common spam filter trigger words, ie. "viagra"
might become "vaigra", or by inserting other symbols within the word,
i.e. "v/i/a/g./r/a".
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The Nigerian Email Spam Scam
•
•
•
Email SPAM Scam
The Nigerian Email Spam Scam
http://www.youtube.com/watch?v=kYNi2gVpuig
• ABC Report on Nigerian Scammers
• http://www.youtube.com/watch?v=8PQANsFisvU&feat
•
•
ure=related
http://www.youtube.com/watch?v=7PVK0R01tRw&feat
ure=related
http://www.youtube.com/watch?v=puYEUs18MFI&featu
re=related
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Passwords
• Combine letters, numbers, and symbols.
• Use words and phrases that are easy for you to remember, but difficult
•
•
•
•
for others to guess.
Avoid sequences or repeated characters. "12345678," "222222,"
"abcdefg,"
Avoid using only look-alike substitutions of numbers or symbols.
– 'i' with a '1'
– 'a' with '@‘
– ‘o’ with a 0’
– as in "M1cr0$0ft" or "P@ssw0rd"
At least 8 characters; more than14 characters is even better
But these substitutions can be effective when combined with other
measures:
– 1$erf@h00k
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Hoaxes, Scams, and Fraud
•
This hoax generated
thousands of emails with
the first day alone.
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Google name or go to Snopes.com
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Virus Hoax
•
While it is true that
PowerPoint files are
capable of containing
computer viruses, there
is no evidence that an
infected file called "Life Is
Beautiful" even exists, let
alone is circulating on
the Internet.
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Swiffer Wetjet
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Typical Email Scam
Subject: Account Confirmation {Account Expires in 4 days}
Date:
Mon, 15 Sep 2008 06:14:39 -0400
From:
Leboyd, Nichole <[email protected]>
Dear Staff/Student
This message is from the IT Service messaging center to all subscribers/webmail users. We are currently upgrading the
webmail data base and e-mail centers due to an unusual activities identified in our email system. We are deleting all
unused Webmail Accounts. You are required to verify and update your Webmail by confirming your Webmail identity.
This will prevent your Webmail account from been closed during this exercise. In order to confirm your Webmail
identity, you are to provide the following data;
Confirm Your WebMail Identity Below;
First Name:
Last Name:
Username/ID:
Password:
Date of Birth:
Warning: Any subscriber/webmail user that refuses to verify and subsequently update his/her Webmail within 4 days of
receiving this warning will lose his/her Webmail Account permanently.
We thank you for your prompt attention to this matter. Please understand that this is a security measure intended to help
protect your Webmail Account. We apologise for any inconvenience.
Regards,
Leboyd Nichole
Webmail Administrator.
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Wells Fargo (Scam)
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Fake Site
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Fake and Real Sites
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Wells Fargo – Reporting Fraud Emails
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PayPal
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USAA
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Changing Who From
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Create Fake Email
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Creating Fake Link
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Receiver
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Looking at Options doesn’t help
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Click on Link…
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RickRoll’D
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Killer Whale Lands On Kayak (?)
•
•
http://www.youtube.com/watch?v=H2KBpauoDNs
http://www.youtube.com/watch?v=NjwxAJYKFbE
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93
Sites to check for hoaxes
•
•
•
http://urbanlegends.about.com/od/internet/a/current_netlor
e.htm
http://www.snopes.com/
http://www.hoax-slayer.com/
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Internet: Safe Surfing
CS 1
Rick Graziani