802.11b - Wireless
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Last Revised 01/14/03
802.11b Operational Modes
- Ad-hoc mode (devices talk directly to one another without an access point)
- infrastructure mode (requires an access point)
Access Point Types:
- Bridge (bi-directional connection to a wired network)
- NAT router type (uni-directional, routes traffic only to a wired network)
- hybrid NAT router + Bridge ( bridges wired and wireless networks, routing them both to the internet using a single IP address)
- 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:
For further information see their excellent document in its entirety:
Security of the WEP algorithm
- Passive attacks to decrypt traffic based on statistical analysis.
- Active attacks to inject new traffic from unauthorized mobile stations, based on known plaintext.
- Active attacks to decrypt traffic, based on tricking the access point.
- Dictionary-building attacks which, utilizing analysis of about a day's worth of traffic, allows real-time automated decryption of all traffic.
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:
Three wireless parts make up
of single chip baseband
Media Access Controllers (MAC).
The family supports three popular system
interfaces: PCMCIA or Compact Flash
and PCI or mini-PCI
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:
Wi-Fi Networking News Daily reporting on Wi-Fi and the whole IEEE 802.11
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
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