802.11b - Wireless

802.11b Characteristics

802.11b Operational Modes

1. Ad-hoc mode (devices talk directly to one another without an access point)
2. infrastructure mode (requires an access point)
     Access Point Types:
   1. Bridge (bi-directional connection to a wired network)
   2. NAT router type (uni-directional, routes traffic only to a wired network)
   3. hybrid NAT router + Bridge ( bridges wired and wireless networks, routing them both to the internet using a single IP address)

802.11b Speed

• Typical throughput of 2.5Mbps to 4Mbps
• WEP enabled networks may experience a 20% to 50% reduction in speed depending on the processing power of the access point
• 802.11b uses the same 2.4 GHz range availbalbe to cordless phones. Resulting interference may result in reduced speed or network failure.

802.11b Security via WEP

Without WEP (Wireless Encryption Protocol) enabled, all network adapters within range of an 802.11b network adapter or access point will connect and join the network. WEP has adequate security for the home / home office envrinoment, but can be compromised.

WEP security Flaws:

WEP uses a stream cipher, the RC4 encryption algorithm. Numerous schemes and programs exist to capitilize on the weakness of the "key scheduling slgorithm" of RC4. Programs such as Airsnort passively monitor the wireless network and devine the master WEP key, allowing unauthorized users to pose as a legitimate user of the network.

Borisov, Goldberg, and Wagner from Berkeley Univ. place the WEP security flaws in four basic categories:

1. Passive attacks to decrypt traffic based on statistical analysis.
2. Active attacks to inject new traffic from unauthorized mobile stations, based on known plaintext.
3. Active attacks to decrypt traffic, based on tricking the access point.
4. Dictionary-building attacks which, utilizing analysis of about a day's worth of traffic, allows real-time automated decryption of all traffic.
For further information see their excellent document in its entirety: Security of the WEP algorithm

802.11b protocol:

802.11b is a half duplex protocol; while it can send OR receive, it can not do so at the same time.

802.11b chipset offerings:

AtmelŪ Corporation
Three wireless parts make up their Fast-VirtualNet™ family of single chip baseband Media Access Controllers (MAC).

The family supports three popular system interfaces: PCMCIA or Compact Flash (AT76C504), USB (AT76C505), and PCI or mini-PCI (AT76C506).

Atheros Communication

The AR5001X Combo WLAN Solution supports three generations of WAN standards and contains three CMOS low-power chips:

• AR5111 5-GHz Radio-on-a-Chip (RoC)
• AR5211 Multiprotocol MAC/baseband processor
• AR2111 2.4-GHz Radio-on-a-Chip (RoC)

AMD 802.11b Report http://www.adapticom1.net/reports/802.11b/AMD-802.11b-report.html

Envara 802.11b Report http://www.adapticom1.net/reports/802.11b/envara-802.11b-report.html

Maxim 802.11b Report http://www.adapticom1.net/reports/802.11b/maxim-802.11b-report.html

Synad 802.11b Report http://www.adapticom1.net/reports/802.11b/synad-802.11b-report.html

Other 802.11b documents:

IEEE 802.11 WIRELESS LOCAL AREA NETWORKS

WiFi Alliance Index

Recipe for a Linux 802.11b Home Network

Planet - The source for 802.11 Business and Technology

Webopedia - 80211

802.11b Community Network List

Anatomy of IEEE 802.11b Wireless

Introducing Apple Airport Extreme

802.11b Networking help tutorial- a wireless DIY starter guide

a directory of public 802.11b hot spots for finding WiFi wireless Internet access network nodes

Exploiting and Protecting 802.11b Wireless Networks

Putting 802.11b to the test

Adapticom, Inc.
P.O. Box 91461
Raleigh, NC 27675-1461
919/870-0608
888-767-7501 (FAX)