Transcript Anatomy of an 802.11 Wi-Fi Enterprise Wireless LAN

Anatomy of an 802.11 Wi-Fi
Enterprise Wireless LAN
Chris De Herrera
Pacific Crest Bank
Chief Information Officer
Webmaster, Tablet PC Talk,
CEWindows.NET
Overview
Glossary of the terms used in Wi-Fi
Wi-FI Characteristics
Hardware Requirements
Ad Hoc vs. Infrastructure
Positioning APs
Security
Demonstration
Competing Wireless LAN Options
Questions and Answers
Glossary
802.11, Wireless Ethernet, Wi-Fi - A wireless local area network
protocol which allows high speed access to network resources. It
operates at 11, 5.5, 2 and 1 megabits per second depending on
distance. It uses the 2.4 ghz spectrum using direct sequence
spectrum (DSS).. WECA is the industry consortium which works
with vendors on interoperability.
ESSID – Extended Service Set Identifier - Specifies which 802.11b
network you are joining. Some systems allow you to specify ANY
SSID as an option so you can join any network.
WEP - Wired Equivalent Privacy - the standard for encrypting data over
an 802.11b wireless network. This 40 or 128 bit encryption has been
shown to be insecure. So the current recommendation is to use a
VPN, limit MAC Address, or 802.1x to secure corporate data.
Additional terms are defined at http://www.cewindows.net/glossary.htm
Wi-Fi Characteristics
• Supports 1,2,5.5 and 11mb/s speeds
• Provides coverage of up to 500 feet indoors and 1500
feet outside
• Up to 100mW of transmit power
• Limited to 3 simultaneous channels of communication –
This affects the coverage design for a given area to
prevent overlapping channels
• Half Duplex – Only one device can transmit at a time
• Supports roaming between access points if they are on
the same subnet and use the same SSID.
Hardware Requirements
• PC Card or Compact Flash Card – see
http://www.cewindows.net/peripherals.htm
(includes antenna sensitivity, power
output, etc)
• Access Point – Really just a bridge
between Wi-Fi and Ethernet.
• Local Area Network
• Ethernet Switch
Ad Hoc vs. Infrastructure
• Ad Hoc is the term used to explain when a user
is connecting to another 802.11b device directly
without an access point. The user must decide
what IP address and subnet to communicate.
• Infrastructure is the term used to explain when a
user is connecting to the wireless LAN using an
Access Point. The Access Point or another
network device can provide services like DHCP
and NAT.
Positioning APs
• Get a floorplan to indicate
where to place APs to
cover the area.
• Test for interference –
2.4 gHz equipment,
Microwaves, Other
Metal Objects
• Test coverage
Security
• You need to secure your data that is sent via
wireless.
• Using WEP is not enough to prevent unauthorized
access to your Wi-Fi LAN. WEP is easy to crack.
• Limiting MAC addresses does not encrypt your data.
• Using 802.1x limits who can access your Wi-Fi LAN
but does not encrypt your data
• Using a VPN encrypts your data and restricts who is
authorized to access your Wi-Fi LAN
• Don’t forget physical security of APs.
• Future – 802.11i
Demonstration
• Basic configuration of a Linksys WAP11
Access Point
Competing Wireless
LAN Options
• 802.11a – Current high speed standard –
54 mb/s. Uses 5 gHz. About ½ the
coverage of Wi-Fi.
• 802.11g – Up and coming standard that
has not been ratified. Backward
compatible with Wi-Fi. Operates at 54
mb/s. Uses 2.4 gHz. About the same
coverage as Wi-Fi.
Anatomy of an 802.11 Wi-Fi
Enterprise Wireless LAN
Questions and Answers
Chris De Herrera
Pacific Crest Bank
Chief Information Officer
Webmaster, Tablet PC Talk,
CEWindows.NET
Anatomy of an 802.11 Wi-Fi
Enterprise Wireless LAN
Chris De Herrera
Pacific Crest Bank
Chief Information Officer
Webmaster, Tablet PC Talk,
CEWindows.NET