Wired Equivalent Privacy (WEP) Security for madwifi

=========================================================================

This document details the commands currently used to configure
a station or AP to use WEP security.

WEP is known to have vulnerabilities that make it a less attractive
for networks with stringent security requirements. However, wide
deployment and relative ease-of-use make it a simple way to add
link layer encryption between stations (STAs) and access points
(APs).

The WEP modes most commonly available on 802.11 implementations
are:

    1) WEP 40/64 bit key, open 802.11 authentication
    2) WEP 104/128 bit key,  open 802.11 authentication
    3) WEP 40/64 bit key, shared key 802.11 authentication
    4) WEP 104/128 bit key, shared key 802.11 authentication


The commands used to configure an Atheros interface (in this case,
'ath0') are the standard Linux wireless tools (iwconfig, iwpriv
and ifconfig).

To configure the madwifi to use WEP encryption, simply add an
encryption key to the interface using iwconfig. To configure the
driver to use 802.11 shared key authentication, iwpriv is used
to change the protocol authentication mode.

    iwpriv ath0 authmode 1		# open authentication
    iwpriv ath0 authmode 2		# shared key authentication
    iwpriv ath0 authmode 3		# 802.1x authentication

These sets of commands work for a station in each of the 4
cases above.

    1) iwconfig ath0 essid <yourAPssid> key 0123-4567-89

    2) iwconfig ath0 essid <yourAPssid> key 0123-4567-8901-2345-6789-0123-4567-8901

    3) iwconfig ath0 essid <yourAPssid> key 0123-4567-89
       iwpriv ath0 authmode 2

    4) iwconfig ath0 essid <yourAPssid> key 0123-4567-8901-2345-6789-0123-4567-8901
       iwpriv ath0 authmode 2

If you want the driver to perform as an AP, you can add 'mode
master' to the iwconfig line.

The interface MUST be brought UP for the driver to associate
with the AP (or an AP to accept new stations). This is achieved
using ifconfig

     ifconfig ath0 X.X.X.X up


Known Problems
==============

Switching 802.11 authentication modes after entering a WEP key
AND after entering a new authmode sometimes erases the key from
the driver configuration. e.g. issuing

     iwpriv ath0 authmode 1

after following steps 3 or 4 clears the WEP key.


Happy privacy :)