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 802.11/11b 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 802.11 standard, has been omitted for new 802.11b platform

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

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

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)

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?