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Chapter Overview

Wireless Technologies Wireless Security

Wireless communication Wireless communication is the transfer of information over a

distance without wire Short distance – TV remote Long distance – radio

Wireless communication can be via: radio frequency communication, microwave communication, for example long-range line-of-sight

via highly directional antennas, or short-range communication, or infrared (IR) short-range communication, for example from remote

controls or via Infrared Data Association (IrDA). Applications may involve

point-to-point communication, point-to-multipoint communication, broadcasting, cellular networks and other wireless networks.

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Wireless networking Use various types of unlicensed 2.4 and 5 GHz WiFi

(Wireless Fidelity) devices Is used to connect computers (mostly laptops) users Another common use is for mobile networks that connect

via satellite. We use wireless network:

To span a distance beyond the capabilities of typical cabling to overcome situations where wiring is difficult or financially impractical,

To link portable or temporary workstations, To remotely connect mobile users or networks.

Generally, we refer them as IEEE 802.11

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Basic operation model

Half-duplex Broadcast Using 2.4 and 5 GHz radio frequencies

These are FCC released for public use The 900MHz and 2.4 GHz are referred as

ISM (Industrial, Scientific, and Medical) The reason you cannot use cell phone in hospitals

The 5 GHz is knowns as (UNII) Unlicensed National Information Infrastructure

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Where is 2.4 GHz

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802.11 network standards (Wiki)

802.1Release

Freq. Bandwidth Data rate per stream

Allowable

ModulationApx. indoor range

Apx. Outdoor range

Protocol (GHz) (MHz) (Mbit/s) MIMO str

eams(m) (ft) (m) (ft)

– Jun-97 2.4 20 1, 2 1 DSSS 20 66 100 330

a Sep-995

206, 9, 12, 18, 24,

36, 48, 54 1 OFDM35 115 120 390

3.7 -- -- 5,000 16,000

b Sep-99 2.4 20 1, 2, 5.5, 11 1 DSSS 38 125 140 460

g Jun-03 2.4 201, 2, 6, 9, 12, 18,

24, 36, 48, 54 1 OFDM, DSSS 38 125 140 460

n Oct-09 2.4/5

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7.2, 14.4, 21.7, 28.9, 43.3, 57.8,

65, 72.2

4 OFDM

70 230 250 820

4015, 30, 45, 60,

90, 120, 135, 150 70 230 250 820 6

In door range

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Channels

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Benefits of 802.11n

Up to 250 Mbps 40 Mhz channels

Waste less “real estate” MAC Efficiency

Less protocol communication overhead Multiple-Input Multiple-Output (MIMO) support

(pronounced my-moh or me-moh) Need support of both NIC and AP

Great for home video $$$, with little business values

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MIMO

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Wireless Network Components

Wireless Access Points Can be very different for an enterprise vs. home

usage Always has a port to connect to wired network

Wireless Network Interface Card Many types

Build in PCI USB

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Antennas

Omni directional Directional (Yagi)

Point to point Longer range

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Installing a wireless network

Add an access point (AP) Configure it with its IP address 192.168.1.2 and a browser or

software cames with it At least add a name for your network

You can select not to broadcast the network name, but it must have a name (also called Service Set ID, SSID)

May consider not to set the security initially Make sure the wired ports work

NIC part Turn on the Wi-Fi button and let your computer search for a

Wi-Fi network Move it up the list of networks if necessary

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Infrastructure Mode: Basic Service Set (BSS)

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Security Open access out of the box Basic security

Service Set ID – need to know the network to access The device name Does not have to broadcast SSID is sent clear text in client messages (required )

Shared key authentication Wired Equivalent Privacy (WEP) A key entered at the NIC config AP sends client a message and asks the client to encrypt with

the key and authenticated only if it can do that It is possible to decipher the key with the clear text and the respond Or just “replay” if the same message is sent for authentication

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Security (2) Wired Equivalent Privacy (WEP)

A key entered at the NIC config and AP config Key must match in order to communicate with the AP Save enough for home network, not suitable for large networks May have multiple so you can issue a few temporary ones Still has holes

MAC address authentication The MAC address of NICs are entered to

communicate

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Security (3)

RADIUS (Remote Authentication Dial In User Service) Authentication, Authorization, centralized

access, and accounting supervision User ID and password in clear text on the

RADIUS server

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Security (4)

TKIP (Temporal Key Integrity Protocol) Build on top of WEP Use up to 128-bit encryption Each package has it own key = Basic Key + Mac

Address + 48-bit packet serial number Cannot replay

Can still be attacked (differ from our book) Wi-Fi Protected Access (WPA and WPA2)

Use an encryption mode with mathematically proven security when select AES as the encryption method

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WPA/WPA2

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Locking things down

Once you have tested the AP and NIC with open access – no security, locking everything down with WPA

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Wireless for enterprise

Very different game APs need to have 10% overlap in terms of

coverage areas Security considerations

Keys MAC Accounting

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The ad hoc mode

Computer and computer can communicate without access points

Generally not recommended Need to change setting at the NIC

configuration level

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?

Will wireless networks replace wired networks

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