version 1.1 2006slide 1 format of lecture introduction to wireless wireless standards applications...
TRANSCRIPT
Version 1.1 2006 Slide 1
Format of lecture
Introduction to WirelessWireless standardsApplicationsHardware devices Performance issues Security issues
Version 1.1 2006 Slide 2
Wireless Technology
Wireless and mobile computing are the keywords Very topical/excitingThis technology not yet maturePromises that we can improvise our existing
networks without having to lay new wires - roving staff will just have to insert a wireless card into their device and join the network
Interesting to compare the what the Telco’s are doing with 3G and how this rivals WiFi hotspots
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Wireless Technology
Wireless technology has to compete with digital satelliteCablephone lines (HomePNA) 10MbpsPower line (HomePlug) 14Mbps
Wireless broadband technology (WiMax) gives wire-free transmission of two way multimediaBandwidth is an issue here
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Wireless Technology
What is on the market/coming?Communication cards to allow data from personal
digital assistants to be synchronised with desktop PC’s
Cards to link laptops and PC’s with Global System for Mobiles(GSM) based phones and local area network devices
All the above enables firms to set up wireless networks without having to use Ethernet cable
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Wireless Protocols
Wireless LANBluetoothWAP/GPRS/UMTSSWAP - Shared Wireless Access Protocol3G - third generation cellular standard
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Wireless versus Wired networks
Using Radio frequency (2.4GHz and 5GHz)Easy to setup a small office or home office
(SOHO)MobilityTravel through wallEasy for network reconstruction
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What is WiFi?
Wireless LAN IEEE 802.11x networkPromulgated by an association called WiFi
AllianceWiFi Alliance certifies all wireless LAN
IEEE802.11x based products for interoperability
All IEEE802.11x based products that passed the WiFi Alliances are called WiFi
Wireless Fidelity
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WiFi Standards
IEEE 802.11aAn IEEE standard for a wireless network that
operates at 5 GHz with rates up to 54Mbps IEEE 802.11b
An IEEE standard for a wireless network that operates at 2.4 GHz with rates up to 11Mbps
IEEE 802.11g – referred to as 54g (but don’t confuse that with the 54Mbps!)An IEEE standard for a wireless network that
operates at 2.4 GHz with rates up to 54Mbps
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WiFi Standards
WPA (WiFi protected Access)TKIP encryption and protects against unauthorized
network access through the use of a pre-shared key (PSK)
WMM (WiFi MultiMedia)packet prioritisation that meet IEEE 802.11e
quality of service standard.Packets containing time-dependent data such as
audio or video to be sent ahead of data that can safely wait a few microseconds
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WiFi Hardware
Access points (APs)PCMCIA cards/ PC cardsUSB adaptersPCI network cardsWireless routers
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WiFi Applications
RetailsWarehousesHealthcareEducationhttp://www.wifinetnews.com/
News about wifi and also see if you can find out the hotspot(s) around the Stoke-on-Trent area
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WiFi topology
Ad HocWithout use of Access PointPeer-to-peer style communicationRecommended 3 or less users per channel
InfrastructureCommunication each other devices by the use of
Access Point About 10-30 users per access point
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Ad Hoc vs Infrastructure
Ad Hoc can be setup instantly for temporary solution
Scalability is limited to Ad HocCoverage ReliabilityEfficiency
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Security choices
Network security ensures the communications and files are protected
How important of the security depend on how you want to use the network.Browsing internet and mp3 streaming may not need a
securityInternet shopping or purchasing will use SSL security
There are several way to protect your data confidentiality while transmitting
In WLAN, you can change your SSID, WEP or WPA or latest technology WPA2
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Wireless surfing
Common knowledge that some users use someone else’s network connection to use the Internet “piggybacking”Hi-gain antenna example that I use
How do you know someone is using you?If infrastructure – you don’t – would have to look at router
logsAd-hoc – shows in connections window
How do they know you are not using them in return?
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WEP
Wired Equivalent PrivacyEncrypt data over the radio wavesImplemented in MAC layer – NIC encrypt the frame
before transmitUsing 64bits or 128bits encryption keysShared secret keyYou need to provide 40 bits (10 digit Hex) or 104bits (26
digit Hex)24 bits Initialisation Vector (IV) for generating key
sequence
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Limitation of WEP
Share, static keysWEP only encrypt frame within wireless
station but not within wired networkLimited IV numbers and may increase
collision - IV repeats after sending 26GB. Recovery attack - the data can be
manipulated after a few hours by tracking repeating IV
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WPA and WPA v2
WiFi Protected AccessDifferent key for each user48 bit IV – defeats recovery attack on WEPUse Temporal Key Integrity Protocol (TKIP)
which dynamic change keys on transmissionMore information on http://www.wifi.org