6 Networking Part2

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Computer Networking Part 2

andInternet Safe Suring

CS 1

Rick Graziani

Cabrillo College

Spring 2006


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Rick Graziani [email protected] 2

Review

Network LANs IP Configuration Internet

TCP/IP DSL/Cable Modem with a Router


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What is a network?

A computer network is a series of computers and other devicesinterconnected by communication paths.

Computer networks include: LANs and WANshttp://www.albany.edu


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LAN Local Area Network

A LAN: Operates within a limited geographical area

Controlled by local administration

Allows local users to:

Share printers

Access local file servers with software and data

Access the Internet


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Creating an Ethernet Network

To start, your computer must have an Ethernet Network Interface Card (NIC).

Ethernet NICs have an RJ-45 interface or port. Hubs and Switches are used to connect computers, printers and other devicesin the Ethernet LAN.

Ethernet cables, i.e. Cat-5 or Cat-6 cables (Category 5, Category 6) are usedto connect computers to the hubs and switches.

Cat-5 cable connects computer NIC to hub or switch.


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IP Configuration

To communicate with other computerson your network you need to properlyconfigure:

IP Address (of your computer)

Subnet Mask (of your computer)

To communicate with computersoutside your network you need toproperly configure:

Default Gateway IP Address

To be able to use domain names, like

www.cabrillo.edu, instead of IPaddresses you need to properlyconfigure:

DNS (Domain Name System)Server IP Address


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IP Configuration: Default Gateway

Any information that needs to be sent to IP Addresses outside your

network is sent to the Default Gateway or Router.

To the Internet192.168.1.10

192.168.1.1



IP Configuration: DNS

Hey, 207.62.87.54, what is the IPAddress for www.yahoo.com?

It is 66.94.230.47

YahooWebServer

Hey, 66.94.230.47,please send me yourweb page.

Here, 192.168.1.10,here is my web page.



Setting the IP Configuration Information

IP information can be configured: Statically

Dynamically

Using a DHCP (Dynamic Host Configuration

Protocol) Server



IP Configuration: Dynamic Configuration

Im booting up, if there is a DHCP

Server out there, I need my IPConfiguration Information!

DHCPServer

Here is your IPAddress, SubnetMask, IP Address for

the Default Gateway(router), and IPAddress for the DNSServer!

Wh i h



What is theInternet?

The Internet was originally designed by DARPA (DefenseAdvanced Research Projects Agency) in response to the

U.S.S.R. launching Sputnik, the first satellite. Out of this came the Internet, a way for computers to

communicate from different parts of the world.

These computers can be any type of computer using anytype of operating system, as long as they are using theprotocol TCP/IP.



What is TCP/IP? What is a protocol?

A protocol is nothing more than an agreement or rules togovern a way of communicating.

The sender and receiver, and everyone in between, must

agree on the rules, the protocol.

The actual letter(data) is inside(encapsulated)the envelope.



What is TCP/IP? What is a protocol?

Protocol: An agreed form of communications.



YahooWeb

Server

Source IP Address:192.168.1.10

Destination IP Address:

66.94.230.47

Destination IP Address:192.168.1.10

Source IP Address:66.94.230.47

192.168.1.10 66.94.230.47

Inside envelope:Request for webpage

Inside envelope:Web page



DSL or Cable Modem: No Router

204.180.205.1Public Address

Hacker can only get to publicaddress and not private address

DSL or CableModem

Routers can help protect your DSL or Cable ModemNetwork.



When using NAT (Network

Address Translation, theRouter helps hide yournetwork from attackers.

204.180.205.1

Public Address

192.168.1.10Private Address

Hackers can only get to public

addresses and not private addresses

DSL or Cable Modem: With a Router

Internet



Bandwidth

Bandwidth - The amount of information that can flow through anetwork connection in a given period of time.

Usually measured in bits per second (bps) bps: bits per second

Kbps: thousands of bits per second

Mbps: millions of bits per second



Networking Part 2

Circuit Switching versus Packet Switching Wireless Careers in Information Technology



WAN Link Options



Circuit Switched

Circuit Switching: A form of data communication which establishes a

single connection or circuit between source and destination to carry thedata 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 thatthere is a continuous circuit from the originating caller to that of thecalled party.



Packet Switching

Frame Relay,X.25, ATM

Packet Switching: A form of data communications which breaksa data stream into small sections, sends them separately by thebest available channels and reassembles the original datastream at its destination.

An alternative is to allocate the capacity to the traffic only when itis needed, and share the available capacity between many

users.



Wireless Access Point

A wireless access point is a device that connectswireless devices (laptops, etc.) to a wired network, usuallyan Ethernet LAN.



Wireless Access Point

In our example the wireless access point (AP) will include aRouter.



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: WPA, WEP, or none

Router settingsinclude: IP Address,Subnet Mask,Default Gateway,and DNS Serverinformation


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SSID

The SSID is what will be displayed when people withwireless 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

Switch or Hub Connect wired computers DHCP Server (optional)

Wireless

SSID: MyHomeNetwork DHCP Server: (optional) Channel: 11

Encryption Function: WPA

MAC address forAPs IP address


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You choose

There are many resources to discuss the possible healthrisks or wireless LANs.

As a networking and WLAN user and instructor I have myown thoughts which I will share.

If you are concerned, then research the information andcome to your own conclusions.

The following information is from my own research andexperience.


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Wireless Frequency

Wireless APs operate at:

2.4 GHz

5 GHz

2 GHZ! Thats the same as my microwave oven, isnt 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 muchpower.

A 25 watt light bulb is safe, but it wouldnt be safe at 250,000watts

Wireless access points generate signals at 1/10th of a watt.

Like all electromagnetic waves, the signal does not fade in alinear manner, but inversely as the square of the distance.


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Rick Graziani [email protected] 30www.britishlibrary.net


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Inverse square law

Double the distance of the wireless link, we receive only of theoriginal power.

Triple the distance of the wireless link, we receive only 1/9 the originalpower.

Move 5 times the distance, signal decreases by 1/25.

Point A

2 times the distance the power of Point A

10 20 30 40 50 100

3 times the distance1/9 the power of Point A

5 times the distance1/25 the power of Point A

10 times the distance1/100 the power of A


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Putting it in some perspective

Measurements from an antenna transmitting 100mW at 1 inch

Remember a milliwatt is 1/1,000thof 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 to1,000,000,000,000 stronger.

A 250,000 watt up to a 250,000,000,000,000 watt light bulb would alsobe dangerous.


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Wireless Security Everyone can hear

Others can hear or capture your information.

Wireless signals are propagated, sent, similar to our voicesound waves.


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Wireless Security Everyone can hear

If we dont 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 - WPA

WPA (WiFi Protected Access) is currently the best option.

The password is configured on both the wireless access point and thecomputer.


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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

DriftNetCommView

Wi l S i


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Wireless Security

Your web browsing or email access should already be secured.

Look for the lock


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C i I f i T h l


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Careers in Information Technology

C t S t S i li t


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Computer Support Specialist

Installing computer hardwareand software.

Troubleshooting Maintenance and upgrades

N t ki S t Ad i i t t


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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

N t ki N t k T h i i /A l t


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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

K i t h l


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Keeping up on technology

Wireless Security


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Internet: Safe Surfing

S f S fi


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Safe Surfing

Adware

Pop-ups Spyware

Blocking Pop-ups

Java Traps or Pop-Up Hell Spyware

Blocking Spyware

Cookies Virus Protection Spam

Blocking Spam

Adware


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Adware

Adware or advertising-supported software is any software applicationin which advertisements are displayed while the program is running.

Displays the ads in pop-up windows or through a bar that appears on acomputer screen.

Adware helps recover programming development costs, and helps tohold down the price of the application for the user (even making it freeof charge)and, of course, it can give programmers a profit, whichhelps to motivate them to write, maintain, and upgrade valuablesoftware.

What are Pop ups? (Wikipedia org)


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What are Pop-ups? (Wikipedia.org)

Pop-up ads are a form of online advertising on the Web where certainwebsites 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.

From Gain Publishing:


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gwww.gainpublishing.com/ about/

http://www.gainpublishing.com/about/http://www.gainpublishing.com/about/


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For early advertising-supported websites, banner ads were sufficientrevenue generators.

But in the wake of the dot com crash, prices paid for banneradvertising clickthroughs decreased and many vendors began toinvestigate more effective advertising methods.

Pop-up ads by their nature are difficult to ignore or overlook, and areclaimed to be more effective than static banner ads.

Pop-ups have a much higher click rate than web banner ads do.



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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-upblocking to Internet Explorer.

Some users install non-Microsoft ad-blocking software instead. Advertisers continually seek ways to circumvent such restrictions. Many of the latest pop-ups are created using Flash and have extensive

animation and trickery.

Ultimateirony!


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From Microsoft


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From Microsoft

With Windows XP Service Pack 2 (SP2) Internet Explorer allows youto prevent most pop-up windows from appearing over pages you wantto view while you're using the Internet.

When you install SP2, Pop-up Blocker is turned on in Internet Explorerand set to the medium setting, which means it will block mostautomatic pop-ups.

Block Pop-up Windows with Internet


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p pExplorer

http://www.microsoft.com/windowsxp/using/web/sp2_popupblocker.mspx

C/NET Pop ups mean more $$$


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C/NET Pop-ups mean more $$$

Publishers willingly allow pop-ups or pop-unders because theycommand higher prices, and they're in high demand byadvertisers.

Ad executives say they can cost advertisers about $10 perthousand sent for top-rated sites.

That compares with between $2 and $3 per thousand for astatic banner ad that appears on the same popular site.

The Web sites that sold or disseminated the most pop-up adsin the month of April 2005 include CNN.com, ESPN.com,Excite.com, Weather.com, and The New York Times.

Java Trap or


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pPop-up Hell

Pornographic websites are among the most common users of pop-upads.

Some particularly vicious types of pop-up ads have been specificallydesigned 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.

What are Pop-ups? (Wikipedia org)


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Pop-up ads can also be spawned as a separate process (that is to say,apart from the browser) on the user's local computer.

This is typically because of a spyware infestation, or because the userhas voluntarily (or involuntarily) installed adware.

Spyware (Wikipedia org)


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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:

the delivery of unrequested advertising (pop-up ads in particular),

harvesting private information

re-routing page requests to illegally claim commercial site referal fees Spyware as a category overlaps with adware Spyware or Malware in a broader sense can include: adware, remote

access trojans (RATs), keystroke loggers, denial-of-service (DoS) attackagents, probe tools, and other backdoor network threats (including most

popular remote access tools).

Fighting Spyware


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Fighting Spyware

Spybot (www.safer-networking.org) PestPatrol (www.pestpatrol.com)

Cookies


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Cookies

A cookie is information sent by a

server to a browser and then sentback to the server each time itaccesses that server.

They were invented by LouMontulli, a former employee ofNetscape Communications.

Amongst other uses, cookiesenable websites to be customizedfor individual users oncebrowsing patterns have beenestablished.

Cookies can however causepotential security problems asinformation such as credit carddetails might be collected via acookie.

Cookies can however, only store

information that you provide.

Cookies - Purpose


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Cookies - Purpose

Typically this is used to authenticate or identify a registered user of aweb site as part of their first login process or initial site registrationwithout requiring them to sign in again every time they access that site.

Other uses are maintaining a "shopping basket" of goods selected forpurchase during a session at a site, site personalization (presentingdifferent pages to different users), and tracking a particular user's

access to a site.

Cookies - Permissions


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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

Virus Protection


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Virus Protection

In computer security technology, a virus is a self-replicating program that spreads by inserting copies ofitself into other executable code or documents

Spam (Wikipedia)


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Spam (Wikipedia)

Spamming is the act of sending unsolicited electronic messages inbulk.

The most common form of spam is that delivered in e-mail as a form ofcommercial advertising.

Spamming has been considered by various commercial, government,and independent entities to be one of the foremost social problemsfacing electronic media today.

Many attempts have been made to curb this problem including e-mailfiltering, contractual measures such as Internet Service Providers'acceptable-use policies, laws such as the Can Spam Act of 2003 and

market pressures such as boycotts of those who use or support spam.

CAN-SPAM Act of 2003 (Wikipedia)


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CAN SPAM Act of 2003 (Wikipedia)

The CAN-SPAM Act of 2003, signed into law by President Bush on

December 16, 2003, establishes the first national standards for thesending of commercial e-mail and requires the Federal TradeCommission (FTC) to enforce its provisions.

The bill's full name is an acronym: Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003.

It also requires the FTC to promulgate rules to shield consumers fromunwanted mobile service commercial messages.

The bill permits e-mail marketers to send unsolicited commercial e-mailas long as it contains all of the following:

an opt-out mechanism;

a functioning return e-mail address;

a valid subject line indicating it is an advertisement; and the legitimate physical address of the mailer.

The legislation also prohibits the sale or other transfer of an e-mailaddress obtained through an opt-out request. It criminalizes the useof automated means to register for multiple e-mail accounts from

which to send spam. It prohibits sending sexually-oriented spamwithout clear markin s.

Anti-Spam
http://www.giantcompany.com/?PID=A22227


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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 theirmessages.

Spoofing e-mail addresses - spammer modifies the e-mail messageso it looks like it is coming from another e-mail address.

Among the tricks used by spammers to try to circumvent the filters is tointentionally 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".

Spam
http://www.giantcompany.com/?PID=A22227http://www.giantcompany.com/?PID=A22227http://www.giantcompany.com/?PID=A22227


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Spam


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Internet: Safe Surfing

CS 1Rick Graziani

Spring 2006

6 Networking Part2

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