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Pertemuan 14

Komunikasi, Jaringan, & Pengamanannya (Lanjutan)

Matakuliah : T0604-Pengantar Teknologi Informasi

Tahun : 2008

Versi : 2.0/0.0

Williams, B.K, Stacy C. Sawyer (2007). Using Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition, McGraw-Hill, New York. ISBN-13: 978-0-07-110768-6

Sumber: Chapter 6. Communications, Networks, & Safeguards, p.309

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :

• menjelaskan kegunaan dan jenis-jenis media komunikasi nirkabel, ancaman dan pengamanan jaringan, serta teknologi komunikasi di masa depan (C2)

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Outline Materi

• Wireless Communications Media

• Cyberthreats, Hackers, & Safeguards

• The Future of Communications

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Wireless Communications Media• Electromagnetic spectrum of radiation is the basis of all

telecommunications signals– Includes the longest radio waves (9 kHz) and audio waves (sound),

up through gamma rays that come from nuclear decay (thousands of gigahertz)

– Radio-frequency spectrum is the part of the electromagnetic spectrum that we use for radio communication

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Wireless Communications MediaBandwidth

• Narrowband (or Voiceband)– Used for regular telephone communications– Transmission rate < 100 kilobits per second

• Medium Band– Used for long-distance data transmission or to connect

mainframe and midrange computers– Transmission rate 100 kb to 1 megabit per second

• Broadband– For high-speed data and high-quality audio and video– Transmission rate 1 megabit per second to 100 megabits

per second• US households get 4 – 5 MB while Japanese get 100

MB per second

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Wireless Communications Media

• Infrared Transmission– Sends signals using infrared light– Frequencies are too low to see (1-4 Mbits per second)

• Broadcast Radio– AM/FM, CB, ham, cellphones, police radio– Sends data over long distances using a transmitter

and a receiver

• Microwave Radio– Superhigh frequency radio waves (1 gigahertz)– Requires line-of-sight transmitters and receivers

• Communications Satellites

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Wireless Communications Media

• Communications Satellites– These are microwave relay stations in orbit around the earth

- Uplinking: transmitting a signal from ground station to a satellite

– Cover broad service area– Cost $300 million to $700 million each + launch costs– Can be placed at different heights: GEO, MEO, LEO

• GEO – geostationary earth orbit – 22,300 miles up above earth– Always above equator

• MEO – medium-earth orbit– 5,000 – 10,000 miles up

• LEO – low-earth orbit– 200 – 1,000 miles up– Has less signal delay than GEO, MEO satellites

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Wireless Communications MediaGPS

• Global Positioning System– 24 earth-orbiting satellites continuously transmitting

timed radio signals– Each satellite circles earth twice each day at 11,000

miles up– GPS receivers pick up transmissions from up to 4

satellites and pinpoint the receiver’s location– Accurate within 3 – 50 feet, with a norm of 10 feet

accuracy– GPS receivers contain map files that are displayed

based on the GPS position to guide users– Many GPS receivers have speech chips, too

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Wireless Communications MediaOne-way Pagers

• One-way pagers are radio receivers that receive data sent from a special radio transmitter– Radio transmitter sends out signals over the special

frequency– Pagers are tuned to that frequency– When a particular pager hears its own code, it

receives and displays the message

Discussion Question: Why do airplane rules require you to turn off pagers and cellphones during flight?

Answer: Pilots use radar and radio to determine their position and communicate with ground control. Pager and cellphone signals use radio, too, and competing signals can interfere with each other

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Wireless Communications MediaLong-Distance Wireless

• Two-way pagers: Blackberry and Treo• 1G: First Generation Cellular

– Analog cellphones– Designed for voice communication using a system of

hexagonal ground-area cells around transmitter-receiver cell towers

– Good for voice – less effective for data due to handing off

• 2G: Second Generation Cellular– Use same network of cell towers to send voice and

data in digital form over the airwaves– Required digital receivers on original analog

celltowers

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Wireless Communications Media2G Wireless

• There are two competing, incompatible standards– CDMA – Code Division Multiple Access

• Transmission rates 14.4 kilobits per second• Used by Verizon and Sprint

– GSM – Global System for Mobile Communications• Transmission rates of 9.6 kilobits per second• Used by Cingular and T-Mobile, as well as Western Europe,

Middle East and Asia• US GSM and European GSM use different frequencies

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Wireless Communications Media2.5G Wireless

• Data speeds of 300–100 kilobits per second– GPRS – General Packet Radio Service

• An upgrade to 2.5G• Speeds of 30 – 50 kilobits per second

– EDGE is Enhanced Data for Global Evolution• A different 2.5G upgrade• Speeds of up to 236 kilobits per second

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Wireless Communications Media3G Wireless

• Third generation wireless– High speed data: 144 kilobits per second up to 2

megabits per second– Accept e-mail with attachments– Display color video and still pictures– Play music – Two important upgrades:

• EV-DO – Evolution Data Only– Average speeds of 400 – 700 kilobits per second, peaks of 2

megabits per second

• UMTS – Universal Mobile Telecommunications System– Average speed of 220 – 320 kilobits per second

Discussion Question: If your cellphone can download and play music, do you still need an i-pod?

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Wireless Communications MediaShort-range Wireless

• Local Area Networks– Range 50 – 150 feet– Include Wi-Fi (802.11) type networks

• Personal Area Networks– Range 30 – 32 feet– Use Bluetooth, Ultra wideband, and wireless

USB

• Home Automation networks– Range 100 – 250 feet– Use Insteon, Zigbee, and Z-Wave standards

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Wireless Communications MediaShort-range Wireless

• Wi-Fi (802.11) networks– Wi-Fi b, a, and g correspond to 802.11b, 802.11a, and 802.11g– 802.11 is an IEEE wireless technical specification– 802.11b is older, transmits 11 megabits per second – 802.11a is faster than b but with weaker security than g– 802.11g is 54 megabits per second and transmits 50 ft– Wi-Fi n with MIMO extends range of Wi-Fi using multiple

transmitting and receiving antennas – 200 megabits per second for up to 150 ft

• Warning! Security is disabled by default on Wi-Fi

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Wireless Communications MediaShort-range Wireless

• Wi-Fi Security– Why is it disabled by default?

• So non-technical users can get Wi-Fi working more easily

– Why should this bother me?• A person with a $50 antenna can eavesdrop on everything

your computer sends over wireless from a block or two away• This is called “wardriving”

– To read more about this problem, follow these links• http://www.webopedia.com/TERM/W/wardriving.html• http://www.wardriving.com/

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Wireless Communications MediaPersonal Area Wireless

• Bluetooth– Short-range wireless standard to link cellphones,

PDAs, computers, and peripherals at distances up to 30 ft

– Named after King Harald Bluetooth, the Viking who unified Denmark and Norway

– Transmits 720 kilobits per second– When Bluetooth devices come into range of each

other, they negotiate. If they have information to exchange, they form a temporary wireless network

– Bluetooth can also be used to eavesdrop on networks– Turn it off on your cellphone unless you need it at that

time

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Wireless Communications MediaPersonal Area Wireless

• Ultra Wideband (UWB)– Developed for military radar systems– Operates in 480 megabit per second range up to 30 ft– Uses a low power source to send out millions of

bursts of radio waves each second– 100 times as fast as Bluetooth

• Wireless USB– USB is the most used interface on PCs– The wireless version could be a hit– Range of 32 ft and maximum data rate of > 480

megabits per second

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Wireless Communications MediaShort-Range Wireless for Home

• Insteon– Combines electronic powerline and wireless technology– Can send data at 13.1 kilobits per second with 150 ft range– Replaces X10

• ZigBee– Entirely wireless very power-efficient technology– Can send data at 128 kilobits per second with 250 ft range

• Z-Wave– Entirely wireless power-efficient technology– Can send data at 127 kilobits per second to range of 100 ft– Allows you to remotely program your house!

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Cyberthreats, Hackers, & Safeguards

• Problem: internet was begun to foster collaboration among universities and scientists. They trusted each other. No security was built into the internet.

• Problem: the internet is open-access and is used by some people who are not trustworthy, who take advantage of the lack of built-in safeguards.

• Problem: Most people connect to the internet and use their computers in LANs. All it takes is one computer on a LAN that has been compromised for all computers on it to be vulnerable.

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Cyberthreats, Hackers, & Safeguards

• Denial of Service Attacks– Consist of making repeated requests of a computer or

network device, thereby overloading it and causing legitimate requests to be ignored

– Used to target particular companies or individuals• Worms

– A program that copies itself repeatedly into a computer’s memory or disk drive

– May copy itself so much it crashes the infected computer

– Famous worms include: Code Red, SQL Slammer, Nimda, MyDoom, Sasser

– Primarily target PCs running Microsoft Windows

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Cyberthreats, Hackers, & Safeguards

• Viruses– A deviant program that hides on a floppy, hard

drive, CD, or e-mail that causes unexpected side effects such as destroying or corrupting data

– Viruses self-replicate and try to secretly distribute themselves to other systems

– Famous viruses include the “I Love You” virus– Viruses are published at the rate of about one per

day– To see what the latest ones are, go to

• http://www.symantec.com/avcenter/vinfodb.html

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Cyberthreats, Hackers, & Safeguards

• Trojan Horses – Programs that pretend to be a useful program

such as a free game or screensaver.– Carry viruses or malicious instructions that

damage your computer or install a backdoor or spyware

– Backdoors and spyware allow others to access your computer without your knowledge

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Cyberthreats, Hackers, & Safeguards

• How they spread– Via e-mail attachments– By infected floppies or CDs– By clicking on infiltrated websites– By downloading from infected files from websites– Through infiltrated Wi-Fi hotspots– From one infected PC on a LAN to another

• What can you do about it?– Install anti-virus software and subscribe to the

automatic anti-virus update service

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Cyberthreats, Hackers, & Safeguards

• Hackers are either– Computer enthusiasts, people who enjoy learning about

programming and computers (good)– People who gain unauthorized access to computers or

networks, often for fun or to see if they can (not good)• Crackers

– Malicious hackers who break into computers for malicious purposes

• Script kiddies are technically unsophisticated teenagers who use downloadable software for perform break-ins

• Hacktivists are hacker activists who break into systems for a political purpose

• Black-hat hackers are those who break into computers to steal or destroy information or to use it for illegal profit

• Cyberterrorists attack computer systems so as to bring physical or financial harm to groups, companies, or nations

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Cyberthreats, Hackers, & Safeguards

• Safeguards– Use antivirus software, and keep it current– Install a firewall to monitor network traffic and filter out

undesirable types of traffic and undesirable sites– Use robust passwords –

• Minimum 8 characters with letters, numbers, characters• 4cats is not a good password, but f0UrK@tTz is

– Install antispyware software– Encrypt financial and personal records so only you

can read them– Back up your data, so if your PC is attacked and must

be reformatted, you can restore your data– Never download from a website you don’t trust– Consider Biometric authentication

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Cyberthreats, Hackers, & Safeguards

• Encryption– The process of altering readable data into unreadable

form to prevent unauthorized access• Uses powerful mathematical ciphers to create coded

messages that are difficult to break

– Two forms: • Private Key encryption means the same secret key is used

by both the sender and receiver to encrypt and decrypt a message

• Public Key encryption means that two keys are used – The public key of the recipient is published and is used by the

sender to encrypt the message– The private key of the recipient is secret and is the only way to

decrypt the message

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Future of Communications

• This is a big area of development

• There is a lot of money to be made from faster and more secure broadband communications

• Areas of development include– Global high-speed low—orbital satellite networks for

rural internet and voice connectivity– 4G wireless technology– Photonics to speed up fiber-optic lines– Software-defined radio– Grid computing

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