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PowerPoint Presentation - Cabrillo College


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									Networking Fundamentals - Part 2

                CS 1
            Rick Graziani
           Cabrillo College
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1981 primitive Internet report on KRON

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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.

    Rick Graziani                                           16
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

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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

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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


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 Configuring the AP and Router

Wireless Settings:
• Security: WPA2, WPA, WEP, or none


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•   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)

• 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

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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
         • A 25 watt light bulb is safe, but it wouldn’t be safe at 250,000
     – 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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Inverse square law
                   10                     20            30           40           50                    100

             Point A                                                                   10 times the distance
                                               3 times the distance
                                               1/9 the power of Point A                1/100 the power of A

                      2 times the distance                                5 times the distance
                      ¼ the power of Point A                              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
•      Move 5 times the distance, signal decreases by 1/25.

    Rick Graziani                                                                    28
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.

    Rick Graziani                              32
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.

    Rick Graziani                          34
Wireless Security

                                      CommView   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
•   Wireless Hacking

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MAC Cloning

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Cell Phones do not cause explosions


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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 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

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What are Pop-ups? (

• 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
     – 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: about/

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•      For early advertising-supported websites, banner ads were sufficient revenue
•      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? (
    Rick Graziani                                                  51
What are Pop-ups? (


•     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
• 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.
 Rick Graziani                               52
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    Pop-up, looks real…

     Rick Graziani                     54
Block Pop-up Windows with Internet

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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
•   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 (

• 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
•    Spyware or Malware Can include:
      – keystroke loggers
      – denial-of-service (DoS) attack agents

    Rick Graziani                                        58
Fighting Spyware

• Spybot (
• PestPatrol (
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• 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
•   Cookies only store information
    that you provide.

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First time you login
                                      HTTP Requests: GET
                                      (first time)

       HTTP      HTTP: Response
       Server    Set-cookie: ID
                                HTTP Requests (GET)        HTTP Client
 Web server can now             now include ID -
 track clients activities       5551212
 on the web site.

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Each time you login…

                                       HTTP: Cookie 5551212 included

                                      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 self-
    replicating program that spreads by inserting copies of
    itself into other executable code or documents
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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
Rick the Chinese the entry into the Google work systems.”
     Graziani                                                 68
Computer Virus, Spyware

•   Computer Virus, Spyware

•   How Computer Viruses Work

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May 4th,

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Spam (Wikipedia)

•   Spamming is the act of sending unsolicited electronic
    messages in bulk.

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• 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
•   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".
Rick Graziani                                        72
The Nigerian Email Spam Scam

• Email SPAM Scam
• The Nigerian Email Spam Scam

•   ABC Report on Nigerian Scammers

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• 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,"
•   Avoid using only look-alike substitutions of numbers or symbols.
     – 'i' with a '1'
     – 'a' with '@‘
     – ‘o’ with a 0’
     – as in "M1cr0$0ft" or "P@ssw0rd"
•   At least 8 characters; more than14 characters is even better
•   But these substitutions can be effective when combined with other
     – 1$erf@h00k

Rick Graziani                                        74
Hoaxes, Scams, and Fraud

•   This hoax generated
    thousands of emails with
    the first day alone.

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Google name or go to

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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 <>
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:
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.

Leboyd Nichole
Webmail Administrator.

 Rick Graziani                                                                                         79
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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Changing Who From

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Create Fake Email

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Creating Fake Link

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Looking at Options doesn’t help

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Click on Link…

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Killer Whale Lands On Kayak (?)


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Sites to check for hoaxes


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Internet: Safe Surfing

           CS 1
       Rick Graziani

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