Wireless LAN Technology

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Wireless LAN Technology
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Introduction

• Why look at WLANs?
• Who Cares?
• Maybe he hasnt noticed, but we develop software
  for a living, not wire up networks

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Topics of Discussion

• What is a Wireless LAN
• How does a WLAN work?
• Differing Technologies within the implementation
  of WLANs
  
• Advantages/Disadvantages
• How do I steal my rich stock broker neighbors
  weekly stock tips?
  

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What is a Wireless LAN

• A network of computers and other devices not
  bound by the normal constraints and costs that a
  traditional LAN involves

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How does a WLAN work?

• Data sent through the air using radio frequency
• Broken down into two basic components
  Transmitter/Transceiver
  
• Transmitters/Transceivers transmit data at the
  same radio frequency

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Transmitters

• Access Points(AP)
• Network device responsible for converting wired
  LAN signal into radio frequency
  
• Good for supporting users within a couple of
  hundred feet without degradation of signal

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AP Usability

• Up to three Access Points may be combined to
  create larger field
  
• Automatic strongest field detection allows user
  to wander around with changeovers staged
  transparently
  
• If longer range is necessary, directional
  antennae can be substituted in place of AP
  

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Transceivers

• Wireless Ethernet cards
• Manufactured for both PCMCIA/PCI slots
• Installs just like regular LAN adapters
• Be careful for the antennae

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The 802.11/11b Standard

• Standard developed for WLAN technologies
• Lays out
• FH Frequency Hopping
• DSSS Direct Sequence Spread Spectrum
• Diffused infrared

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Frequency Hopping(FH)

• Uses Bursts of signals
• Maintains a single logical channel
• Is one of the two recommended RF platforms found
  in the 802.11 standard, has been omitted for new
  802.11b platform

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Direct Sequence Spread Spectrum(DSSS)

• Has been adopted in both the 802.11/11b standard
• The use of a wider frequency range while sending
  data allows for higher bandwidth
  
• Breaks up data into small pieces, then transmits
  through a range of frequencies

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Security

• RF signals are unfortunately prone to
  interception by unwanted parties(intentional/unint
  entional)
  
• FH quickly switches from frequency to frequency
  making it hard to keep up
  
• DSSS is scrambled, reducing risk of unintentional
  interception(900 mhz phones, military comm, etc)

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The Big Gun

• WEP Wired Equivalent Privacy
• Uses a key on each end, much like an RSA model
• This implementation is the answer to a lot of
  firms crying out for privacy
  
• Allows for Geographically dependent security

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Performance

• 802.11 used to sustain at most a 6mb/s
  connection
  
• New 802.11b standard commands closer to 11mb/s
• Signal degrades with distance depending primarily
  on environment(open field vs. lead shielding)

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Disadvantages

• Limited range(500 ft, up to 1500 with additional
  AP hardware)
  
• Bandwidth quickly eaten by too many machines(load
  balancing has not yet fully matured within this
  technology)
  
• Limited Maximum Bandwidth (11mb/s)

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Advantages

• Easy, convenient setup
• Highly cost effective for small to mid-range
  shops, or as add-ons to large enterprise
  networks
  
• Minimal downtime for relocation of computer away
  from cubicle with annoying person next door

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Get Rich Quick Scheme

• Now How to get those stock quotes

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Use a Hidden Web Cam

• Or just go ask him, either way, it is
  substantially easier and cheaper than trying to
  hack into a wireless LAN using DSSS combined with
  WEP

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Any Questions?