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RE: Wireless range limiting
From: Nico Darrow <ndarrow () airdefense net>
Date: Wed, 16 Apr 2008 16:29:19 -0400

I wish I had the screenshot of the Newbury demo at defcon. But I remember their entire location tracking system was 
brought down by fake-ap running a cloned AP MAC address.
It's a good idea, but not practical. They required such a high density of sensors to make accurate location 
predictions. And this can be easily circumvented by a well placed MAC-spoofed AP.

Here's my recommendation. If you want to limit the range of an AP, then just disable it's lower bitrates.

Take 802.11b/g router.
Enable 802.11G only mode (if you can. Most internal cards are B/G cards at least).
If you have a high-end AP (Cisco,Symbol,etc), then disable the lower bitrates.

Not only will you lower your range and increase throughput (by not having to worry about slower B clients with longer 
transmit windows), but you also get out of reach of most script kiddies with their 802.11b prism2 chipset ;-P

Just make sure everything is thoroughly tested before rolling out a change like this. Home environments are easy to 
tweak, work environments are harder. Remember nothing beats a good Wireless IDS/IPS :-P

-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of Joshua Wright
Sent: Wednesday, April 16, 2008 12:42 PM
To: Charles Hardin
Cc: wifisec () securityfocus com; security-basics
Subject: Re: Wireless range limiting

Hash: SHA1

Hi Charles,

Charles Hardin wrote:
| A co-worker of mine was recently telling me of a tool he had seen
| several years ago. A utility where you could upload a floor plan of
| your building and specify where your access points are located. You
| could then walk around your perimeter with a wireless client with an
| agent on it that would allow you to marcate the physical boundries of
| where you want the wireless signal to reach and it would reject
| clients outside this range based on the signal.

This is the Newbury Networks product
(http://www.newburynetworks.com/products-rf-firewall.htm).  I don't know
if I trust such a system, since they do not know the transmit power of
someone inside or outside of your facility (they probably assume
something like 100 mW + 3 dBm antenna).  If an attacker has a
higher-gain antenna, they can appear to be inside your facility with a
stronger signal.

I do not claim to know the full detail of the product, but that is my
skeptical 2 cents for today.

- -Josh
Version: GnuPG v1.4.7 (Darwin)


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