Linux wireless networking with the wlan ng drivers

This little note began when I loaded Fedora Core 2 on my Toshiba laptop and then wanted to get my Prism 2.5 wireless PCMCIA card going again.
My card is (for the record) a Trendnet TEW-201PC. (This is an 11 Mbit 802.11b card, now discontinued. Before installing the wlanNG drivers this was detected as an unknown PCMCIA card with an Intersil Prism 2.5 ISL37300P chipset, the wlanNG drivers report a BroMax Freeport 11Mbps 802.11b WLAN Card (Prism 2.5))

Before we get too far into this, let me recommend the following link for background on wireless networking in a Linux context,
namely: Wireless LAN resources for Linux

Back in the good old days, there was an RPM that I just whacked in and away things went. My efforts may culminate in building an RPM myself once I work all this out, we shall see. As of Fedora Core 2, there does not seem to be an off the shelf RPM available. I was temporarily (but falsely) encouraged by the rumor that the drivers had made it into the 2.6 kernel, but alas this is not the case, at least not for the Prism 2.5 driver. (It is the case for a number of drivers for more up to date network chipsets though.)
The thing to do is to go to the linux wlan NG web site to get the driver. This outfile (Absolute Value Systems) maintains the Prism 2.5 driver, and heaven only knows why it never makes its way into the main kernel tree. Whatever the reason, the guys at Absolute Value Systems have a nice set of drivers that do the job.

At the time of my visit (November 1, 2004) the driver was available as linux-wlan-ng-0.2.1pre23.tar.gz on their download page. I downloaded this tarball, along with the FAQ and README on the ftp site and away we go. I note that it nicely has a bunch of wireless card firmware packaged as hex files along with the driver. The appropriate one of these get loaded into RAM in the wireless card, and run there (much less risky than flashing new firmware), very cool.

As per the instructions in the readme, I untarred the files, entered into the directory that results, typed make config, answered a lot of questions (that have reasonable defaults and that are explained in the README), then typed make all. I get a LOT of compile time warnings (makes a person worry), but things do --seem-- to build OK. A make install then puts things where they belong.

The next thing I did was

This is essential for any of the new stuff to be found. Then I insert my wireless card which now blinks and seems to go thru the sequence it always used to, finally ending up with the LED on solid green. A peek at /var/log/messages shows that there was some trouble loading a wlan0 module.

The next thing to do is to edit /etc/modprobe.conf and add the line:

I remove and reinsert the card and things again seem good and there is no more complaint about wlan0 in /var/log/messages. On the other hand, the card is not doing DHCP and getting and IP address and /var/log/messages does not show any chatter about DHCP activity. Running /sbin/ifconfig -a does show a wlan0 entry which is promising. A peek at /etc/sysconfig/network-scripts shows that there is no ifcfg-wlan0, that would indeed explain things.

The next step is to create a /etc/sysconfig/network-scripts/ifcfg-wlan0 file, which I did as follows: 

DEVICE=wlan0
BOOTPROTO=dhcp
ONBOOT=no
TYPE=Ethernet
After this, I pop the card out and in again and I connect to my access point and everything is cool. That are lots of other things you can configure and fiddle with, but for the basic functionality I want, this has me good to go.
Have any comments? Questions? Drop me a line!

Adventures in Computing / tom@mmto.org