Wireless

Bill Moss
January 2002

Introduction

The C600 laptop program machine comes with a Dell TrueMobile 1150 Series mini-PC card that is installed internally. This card is manufactured by Lucent and is based on the Intersil Prism 2 chipset. As mentioned in the article Dual Booting the Clemson Dell Latitude C600 ... and Red Hat 7.1 written last April, everything worked with a default installation of Red Hat 7.1 except for wireless. As of January 2002, we have a choice of two drivers, wavelan2_cs from the manufacturer and orinoco_cs from the open-source community. The driver orinoco_cs is included in the 2.4 kernels. Beginning with 7.2, Red Hat has changed the way network interfaces are configured at boot. Unfortunately, there are a number of bugs in RH 7.2 networking.

Wireless Security

Clemson is currently using a static 128 bit WEP key for wireless security. The only way to configure the Dell C600 mini-PC card wireless card for use on campus is to put the key in plain text in a configuration file. Linux users cannot be given this key and so cannot use this card on campus. Faculty users can configure the card for use with home access points (see home wireless). The good news is that as of August 2002, Clemson will convert from using a static WEP key for wireless security to a virtual private network implementation which will eliminate this problem.

Configuring the orinoco_cs driver

Edit the file /etc/pcmcia/config. Search for the text

card "Intersil PRISM2 11 Mbps Wireless Adapter"
manfid 0x0156, 0x0002
bind "wvlan_cs"

and change wvlan_cs to orinoco_cs.

Installing and Configuring the ORiNOCO wavelan2_cs driver

• Download and install the kernel source from the Red Hat updates site: ftp updates.redhat.com, cd 7.2/en/os/i386, get kernel-source-2.4.9-21.i386.rpm.
• Download the wavelan2_cs driver distribution: http://www.wavelan.com -> Software -> Download Software -> Select a product (Client Products) -> Select a Operating System -> Linux -> Search -> Linux Driver for ORiNOCO (Read this wavelan2_cs release document) -> Download now. You will download WLLI616.TGZ. Rename this file wavelan2_cs-6.16.tar.gz. The document wavelan2_cs release contains all the instructions you will need.
• Download the latest Linux PCMCIA package from http://pcmcia-cs.sourceforge.net.
• You now have down downloaded the three pieces you need. Follow the instructions in the wavelan2_cs release document beginning with Section 4.2. Note that in step 4 you have to specify the directory "/usr/src/linux-2.4" which was created when you installed the kernel source. Also notice that in step 4, you will be notified that your installation uses in-kernel PCMCIA.
  

Edit /etc/pcmcia/config. Find the lines

card "Intersil PRISM 2 11 Mbps Wireless Adapter"
manfid 0x0156, 0x0002
bind "wvlan_cs"

and change them to wvlan_cs to wavelan2_cs. Also make sure this file contains the lines

device "wavelan2_cs"
class "network" module "wavelan2_cs"

Configuring the Wireless Interface RH 7.1

Make a backup copy of /etc/pcmcia/wireless.opts and create a new wireless.opts file containing the following lines.

Case "$ADDRESS" in

   *,*,*,00:02:2D:*)
   ESSID="cuairnet"
   MODE="Managed"
   KEY="**************************"
   ;;

esac

Use the Network Configuration Tool to configure eth1, assuming that your Ethernet card has already been configured as eth0. Set the interface to use the dhcp protocol. The first line in the wireless.opts file create above contains four fields separated by commas. The first field is a scheme field. You can change the first * to "office" and create another entry for your home wireless network with a scheme name of "home". You can switch the scheme from office to home using the command cardctl scheme home. The scheme designated by a * is called the default scheme. You can also use append in lilo.conf to pass the scheme to the kernel at boot giving you a choice of booting wired or wireless. See Wireless Lans in use for more details. Using cardctl ident, you can determine the socket that your card uses. You can then turn your card off using cardctl eject 2 and back on using cardctl insert 2. The command iwconfig will show you the card configuration and link statistics. This command can be used to experiment with the wireless configuration. Permanent changes should be put into the wireless.opts file.

Configuring the Wireless Interface RH 7.2

Start the network configuration tool by looking for "Network Configuration" in the desktop menus or else start the tool by typing neat at the commandline. Under the devices tab choose wireless and configure your wireless card. The configuration information including the wireless key will be written into the file /etc/sysconfig/network-scripts/ifcfg-eth1 assuming that your Ethernet card has already been configured as eth0. The information in this file is read at boot in Red Hat 7.2. The root user can take eth0 and eth1 down and up using the commands ifdown and ifup.Configuration information is read from the files ifcfg-eth0 and ifcfg-eth1. The ONBOOT=no option in the ifcfg-eth1 file does not work. Interface eth1 always comes up at boot.

If you use the cardctl command to eject and then insert the card, configuration information is read from the wireless.opts file (see the previous section) but the interface eth1 does not get updated properly and so does not work. The scheme option for the cardctl command does not work. So there is no way to switch between a home scheme and an office scheme. It appears that RH 7.2 new networking approach is not compatible with the Linux wireless tools. Having configuration information in /etc/pcmcia and in /etc/sysconfig is a mistake. These bugs have been reported to bugzilla. Note also that the command iwconfig eth1 txpower off is not support by wavelan2_cs or by orinoco_cs so it it not possible to turn the radio off as you can in Windows 2000.

Cisco 350 Wireless PC Cards

Clemson is officially supporting on the TrueMobile mini-PC card in the Dell C600 and the Cisco 352 PC card. A Cisco wireless driver is available which supports the 2.4.x kernels. To download the driver, go to http://www.cisco.com -> Software Center -> Wireless Software -> Cisco Aironet Driver & Utilities For Linux -> download AIROLINUXv15000.tar.gz. This is release 1.5.000 dated August 27, 2001. Matt Salzman of Mathematical Sciences indicates that a fully updated RH 7.1 or 7.2 installation, supports the Cisco 352 PC card making the installation of the Cisco driver unnecessary.