Ralink rt73 and wpa_supplicant

rt73 is a WLAN chipset from Ralink. Most of the following information probably also applies to other Ralink WLAN devices if they provide similar wpa_supplicant support, but you will have to extract the wpa_supplicant driver from their packages yourself and possibly search fixes.

To use the rt73 with Linux, the following drivers exist currently:

Drivers

• rt73 provided by Ralink under the GPL (Thanks, Ralink!). Can be downloaded from Ralink's Linux site
• rt73 improved by the rt2x00 Project. I recommend this over the original version, as they integrate better with a current system.
• rt2x00 also by the rt2x00 Project. Completely rewritten and mac80211-based, so it will replace rt73, but the rt73 isn't supported well yet.

rt2x00 should provide support for WPA with wpa_supplicant as soon as its ready, but last time I tried it was unusable with my rt73 (an Asus WL-167G by the way).

rt73 supports WPA-PSK with iwpriv from the Linux wireless-tools, for for WPA-EAP (aka WPA-Enterprise) you need wpa_supplicant. In order to use wpa_supplicant with the rt73 driver by the rt2x00-project, you need two patches: One adds support for the rt73 driver itself, and another fixes a small error which prevents wpa_supplicant from working.

With this patched wpa_supplicant, I can use my rt73 with WPA2 (i.e. 802.11i with CCMP/AES) and radius-based X.509 certificate authentication right now.

Files

• wpa_supplicant-ralink_rt73.patch adds the actual support
• wpa_supplicant-ralink_rt73-fix.patch: fix for the current rt73
• wpa_supplicant_rt73.tar.bz2: gentoo portage overlay containing net-wireless/wpa_supplicant. USE=legacy_ralink_rt73 to enable the patches.
• portage_net-wireless_wpa_supplicant.diff: patch from net-wireless/wpa_supplicant to the version from my overlay

Compiling wpa_supplicant with the patches

tar xzf wpa_supplicant-0.5.7.tar.gz
cd wpa_supplicant-0.5.7
patch -p1 < wpa_supplicant-ralink_rt73.patch
patch -p1 < wpa_supplicant-ralink_rt73-fix.patch
make
# install as usual, e.g.
cp wpa_cli wpa_supplicant /usr/local/bin

wpa_supplicant and gentoo portage

If you don't know how to use the overlay, Gentoo Overlays: Users' Guide is a good resource. Only use the patch if you know how to use it.

Using wpa_supplicant

Currently, I'm using wpa_supplicant as follows:

wpa_supplicant -D ralink -i rausb0 -c /etc/wpa_supplicant/wpa_supplicant.conf -B

The most important port is -D ralink to use the ralink driver for the rt73. I add IP addresses etc. with a custom shell script; I don't know whether/how the driver can also be specified in wpa_supplicant.conf so that no special options need to be passed.

wpa_supplicant.conf looks like this:

ctrl_interface=/var/run/wpa_supplicant

network={
	ssid="my_ssid_here"
	key_mgmt=WPA-EAP
	proto=WPA2
	pairwise=CCMP
	group=CCMP
	eap=TLS
	identity="client"
	ca_cert="/etc/wpa_supplicant/cert/ca.crt"
	client_cert="/etc/wpa_supplicant/cert/client1.crt"
	private_key="/etc/wpa_supplicant/cert/client1.key"
}