Wireless networking

1
Wireless networking

• Unit objectives
• Identify the hardware components needed to create
  a wireless connection
• Differentiate between the various communications
  standards used in wireless networks
• Install and configure a wireless network
  connection

2
Topic A

• Topic A Wireless network devices
• Topic B Wireless networking standards
• Topic C Wireless configuration

3
Wireless

• Technologies and systems that dont use cables
  for communication
• Examples
• Public radio
• Cellular telephones
• One-way pagingSatellite
• Infrared
• Private, proprietary radio
• Wireless networks LAN or WAN

4
Wireless connections

• Can link devices
• Methods
• Infrared
• Radio
• Bluetooth
• Infrared and Bluetooth
• Create wireless connection between two devices
• Radio technology
• Forms larger wireless network

5
Infrared

• Uses pulses of invisible infrared light to
  transmit signals
• Low-speed, line-of-sight connection
• Cant pass through obstructions or around corners
• 9600 bps to 4 Mbps data rate
• 10-20 feet maximum range
• Devices must aim their transceivers at each other
  (line-of-sight technology)

continued
6
Infrared, continued

• No more than a 45 degree angle
• Most popular form Infrared Serial Data Link
  technology
• Serial connection
• 1.5 Mbps
• 20 foot range
• Often found on laptops and PDAs

7
Radio

• Signals sent over electromagnetic radio waves
• Can pass through most nonmetallic obstructions
  and around corners
• Not a line-of-sight technology
• Offers moderate- to high-speed local and wide
  area connections
• Most common technologies
• 802.11b
• 802.11g

continued
8
Radio, continued

• 10 Mbps
• Sometimes called RF technologies
• RF stands for radio frequency
• RF devices have antennae

9
Bluetooth

• Short-distance radio (up to 10 meters)
• Developed by the Bluetooth Special Interest Group
• Includes over 1,000 companies
• Siemens, Intel, Toshiba, Motorola, and Ericsson
• Enables devices to discover other Bluetooth
  devices within range
• Devices self-configure and begin communicating

continued
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Bluetooth, continued

• Shouldnt need to configure communication
  parameters
• Bluetooth devices have antenna often hidden
  inside the device

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Wireless communications

• Enables users to
• Make Internet connection while traveling
• Connect to network while moving about house or
  office
• Important technology for
• Mobile devices
• Internet access in remote locations
• Three types of wireless links
• Indoor point-to-multipoint LANs
• Outdoor point-to-point links
• Outdoor point-to-multipoint links

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Indoor point-to-mulitpoint LANs
13
Outdoor point-to-point links
14
Outdoor point-to-multipoint links
15
Wireless connection components

• Requires
• Wireless network card in the computer
• Wireless router or wireless access point device
  on the network
• Router or WAP broadcasts radio signals
• Wireless network cards pick up the broadcasts

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Wireless NICs
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Wireless access points
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Wireless speeds

• Distance and data rate affected by
• Obstructions within building
• Environment noise
• Recommend wireless LAN access points within 60 to
  90 meters of wireless clients

IEEE speed Data rate Distance (meters)
High 4.3 Mbps 40 to 125
Medium 2.6 Mbps 55 to 200
Standard 1.4 Mbps 90 to 400
Standard low 0.8 Mbps 115 to 550
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WAP placement

• Informal site survey
• Temporary installation WAPs
• Use wireless client to test signal
• Use actual locations for clients
• Formal site survey
• Use field-strength measuring equipment
• Install test antenna in the estimated WAP
  locations
• Strength of test signal at various points within
  the range the WAP will service
• Move test antenna to obtain the best possible
  signal for the wireless coverage area

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Activity A-1
Examining wireless devices
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Topic B

• Topic A Wireless network devices
• Topic B Wireless networking standards
• Topic C Wireless configuration

22
Standards

• Frequency bands divisions
• Military
• Broadcasters
• Amateur radio operators
• Broadcast signal is a security issue
• IEEE standards 802.1x and 802.11

23
802.1x standard

• Port-based, authentication framework for access
  to Ethernet networks
• Designed for wired Ethernet networks
• Applies to 802.11 WLANs
• Requires three roles in authentication process
• Device requesting access
• Authenticator
• Authentication server
• Allows multiple authentication algorithms
• Is an open standard

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802.11 standard

• Operates in the 2.4 through 2.5GHz band
• Used for wireless networks
• OSI Data Link layer
• Two ways to configure a network
• Ad-hoc
• Infrastructure
• Places specification on Physical and MAC layers

25
Access point

• Transparent bridge between wireless clients and
  wired network
• Includes
• At least one interface to connect to the existing
  wired network
• Transmitting equipment to connect with wireless
  clients
• IEEE 802.1D bridging software

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802.11 WLAN standards

• 802.11a
• 802.11b
• 802.11c
• 802.11d
• 802.11e
• 802.11F
• 802.11g

• 802.11h
• 802.11i
• 802.11j
• 802.11k
• 802.11l
• 802.11m
• 802.11n

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Wireless protocols

• Wi-Fi (Wireless Fidelity)
• IEEE 802.11b 11 Mbps 2.4 GHz band
• IEEE 802.11g 20 Mbps 2.4 GHz band
  transmission range of up to 35 meters
• Experience interference from other common
  household devices
• Bluetooth
• Short-range about 100 meters or less
• Low speeds 721 Kbps

continued
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Wireless protocols, continued

• 802.11a
• Improved version of original Wi-Fi
• 54 Mbps 5 GHz band
• Indoor range of up to 35 meters
• Not compatible with 802.11b devices
• WiMAX (IEEE 802.16 Air Interface Standard)
• Point-to-multipoint broadband access
• 10-66 GHz licensed
• 2-11 GHz unlicensed
• 70 Mbps
• 31 miles direct line-of-site

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LAN technologies

• IEEE 1394
• FireWire (Sony) and iLink (Apple)
• Main use video and graphics transfers
• Serial protocol
• FireWire 400 100 to 400 Mbps
• FireWire 800 up to 800 Mbps
• USB
• Bidirectional serial interface
• Main use connect peripheral devices
• USB 1.1 1 to 12 Mbps
• USB 2.0 480 Mbps

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Wi-Fi

• Called AirPort. 802.11b
• Frequency range of 2.4 GHz
• Distance range of about 100 meters
• Up to 11 Mbps
• Range depends on type of signal obstructions
  between transmitter and receiver
• 802.11b popular and inexpensive network
  solution
• Many cordless phones use the 2.4-GHz frequency
  and can interfere with 802.11b network

31
Bluetooth

• Standard for short-range wireless communication
  and data synchronization between devices
• Transmitters and receivers are application-specifi
  c integrated circuits (ASICs)
• Can transmit data at rates as high as 721 Kbps
• Up to three voice channels available
• Easy to configure

32
802.11a/802.11g

• 802.11a
• 5.0-GHz band
• Isnt compatible with 802.11b
• 50 meters max between AP and client
• Faster than 802.11b
• Doesnt encounter interference from 2.4 MHz
  devices
• 802.11g
• 2.4-GHz band
• Backwards compatible with 802.11b
• 54 Mbps

33
WiMAX

• Worldwide Interoperability of Microwave Access
• Wireless DSL and T1-level service
• Emerging Wide Area and Metropolitan Area Networks
  technology standard
• Enables 802.16e devices to roam between current
  wireless hot spots
• Coverage measured in square miles
• Doesnt rely on line-of-sight for connection

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Activity B-1
Comparing wireless networking standards
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Topic C

• Topic A Wireless network devices
• Topic B Wireless networking standards
• Topic C Wireless configuration

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WLAN security risks

• Devices can be lost or stolen
• Session hijacking
• Man-in-the-middle attacks
• Rogue AP
• WAP no default security
• Broadcasts make breaking in easy
• IEEE and WECA developed standards for user
  authentication and media access control

37
Additional risks

• Detectable radio-frequency traffic
• Data is passed in clear text form
• Encryption isnt always strong
• WEP
• One-way authentication mechanism
• One-way open broadcast client connection
• Wardriving
• Warchalking

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WLAN security components

• Access control
• Turn off SSID broadcasts
• Enable a MAC filter on your AP
• Encryption
• Clients and AP use same encryption scheme
• Clients must possess correct encryption key
• Wireless encryption systems vary in ability to
  keep data secure

continued
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WLAN security, continued

• Authentication
• Server authenticates clients
• Stronger access control protection than SSID
  hiding or MAC filtering
• Should still use encryption
• Isolation
• Segregates network traffic
• Two types wireless client isolation (AP
  isolation) and network isolation
• Network isolation through custom routing
• Isolation through your general network design and
  firewall configuration

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Transmission encryption

• Wired Equivalent Privacy (WEP)
• Wi-Fi Protected Access (WPA) Personal
• WPA2
• WPA Enterprise
• RADIUS
• 802.11i

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802.1x authentication
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Activity C-1
Identifying the technology used to implement WLANs
43
Wireless access point configuration

• Assign a service set identifier (SSID)
• Clients use the SSID to distinguish between WLANs
  
• AP typically broadcasts the SSID
• Broadcasts identify the security mechanisms to
  enable clients to auto-configure connections

44
Securing your AP

• Set most secure encryption method compatible with
  clients
• Change AP default admin passwords
• Change default SSID
• Disable SSID broadcasts
• Separate wireless network from wired network
• Put wireless network in an Internet-access only
  zone or DMZ

continued
45
Securing your AP, continued

• Disable DHCP within WLAN
• Enable MAC address filtering on AP
• Enable 802.1x
• Periodically survey site with wireless sniffing
  tool

46
Activity C-2
Configuring a wireless access point (instructor
demo)
47
Wireless clients

• Submit its credentials to the Authenticating
  server
• Secured or 802.1x authenticated connections
• Wireless AP issues a challenge to the client
• AP sets up restricted channel allowing client to
  communicate only with RADIUS server
• RADIUS server accepts only trusted AP connections
• RADIUS server validates the client credentials
• Transmits client master key to wireless AP

48
Wireless Auto Configuration

• Dynamically selects wireless network connection
  attempt
• Based on
• Configured preferences
• Default settings
• Wireless Zero Configuration
• Windows Vista
• Windows XP
• Windows 2000 with download
• Automatically configures address items
• TCP/IP settings,
• DNS server addresses
• IAS server addresses

49
Auto Configuration, continued

• IEEE 802.1x authentication defaults
• Infrastructure before ad hoc mode
• Computer authentication before user
  authentication.
• If NIC is preconfigured with WEP shared key,
  attempts to perform IEEE 802.11 shared key
  authentication otherwise NIC reverts to open
  system authentication

50
Windows CE wireless clients

• Windows CE .NET palm-top computers include
  Wireless Zero Configuration
• Manual configuration options similar to those
  found on Windows Vista and Windows XP
• Supports 802.11a and Native Wireless Fidelity
  (Wi-Fi)
• Non-.NET palm-tops wireless configuration is like
  Windows 2000

51
Activity C-3
Configuring a wireless client (instructor demo)
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Unit summary

• Identified the hardware components needed to
  create a wireless connection
• Differentiated between the various communications
  standards used in wireless networks
• Installed and configured a wireless network
  connection