Wireless LAN Technology

Introduction Why look at WLANs? Who Cares? Maybe he hasn’t noticed, but we develop software for a living, not wire up networks…

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 neighbor’s weekly stock tips?

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

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

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

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

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

The /11b Standard Standard developed for WLAN technologies Lays out:  FH – Frequency Hopping  DSSS – Direct Sequence Spread Spectrum  Diffused infrared

Frequency Hopping(FH) Uses Bursts of signals Maintains a single logical channel Is one of the two recommended RF platforms found in the standard, has been omitted for new b platform

Direct Sequence Spread Spectrum(DSSS) Has been adopted in both the /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

Security RF signals are unfortunately prone to interception by unwanted parties(intentional/unintentional) 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…)

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

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

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)

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

Get Rich Quick Scheme Now… How to get those stock quotes…

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

Any Questions?