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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 29