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Matakuliah
Tahun
Versi
: T0604-Pengantar Teknologi Informasi
: 2008
: 2.0/0.0
Pertemuan 14
Komunikasi, Jaringan, &
Pengamanannya (Lanjutan)
Sumber:
Chapter 6. Communications,
Networks, & Safeguards, p.309
Williams, B.K, Stacy C. Sawyer (2007).
Using Information Technology: A
Practical Introduction to Computers &
Communications. Seventh Edition,
McGraw-Hill, New York. ISBN-13: 978-007-110768-6
1
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)
2
Outline Materi
• Wireless Communications Media
• Cyberthreats, Hackers, & Safeguards
• The Future of Communications
3
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
6-4
Wireless Communications Media
Bandwidth
• 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
6-5
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
6-6
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
6-7
Wireless Communications Media
GPS
• 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
6-8
Wireless Communications Media
One-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
6-9
Wireless Communications Media
Long-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 transmitterreceiver 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
6-10
Wireless Communications Media
2G 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
6-11
Wireless Communications Media
2.5G 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
6-12
Wireless Communications Media
3G Wireless
• Third generation wireless
– High speed data: 144 kilobits per second up to 2
megabits per second
Discussion
– Accept e-mail with attachments
Question: If your
cellphone can
– Display color video and still pictures
download and
– Play music
play music, do
you still need an
– Two important upgrades:
• EV-DO – Evolution Data Only
i-pod?
– 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
6-13
Wireless Communications Media
Short-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
6-14
Wireless Communications Media
Short-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
6-15
Wireless Communications Media
Short-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/
6-16
Wireless Communications Media
Personal 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
6-17
Wireless Communications Media
Personal 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
6-18
Wireless Communications Media
Short-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!
6-19
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.
6-20
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
6-21
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
6-22
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
6-23
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
6-24
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
6-25
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
6-26
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
6-27
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
6-28
Kesimpulan
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