Connecting Your Computer to a Wireless Network


So you're traveling with your SUSE Linux laptop and want to connect to your hotel's wireless network. This can be a problem, but the hurdles can be overcome.

You have basically three problems to deal with when trying to connect to a wireless network:

  • Making sure your card is supported, and the proper drivers and firmware are in place.

  • Locating the access point.

  • Configuring a profile.

This section will cover each of these issues.

Getting Firmware and Drivers in Place

The first issue can be the easiest to solve. Linux supports many different wireless cards, although not always with every feature that the card supports. Firmware (system code that communicates directly with the card) often must be downloaded separately from a Linux distribution. You can download firmware for ACX100, ACX111, and PrismQT cards directly through YaST Online Update, but these packages do not come with the distribution.

Most wireless card manufacturers still produce only Windows drivers, which can present a major headache for non-Windows users. Too often this requires manual setup and configuration of your network configuration file, ifcfg-eth2. This task, however, has been simplified. A second package, ndiswrapper, installable through YaST lets you use the Windows drivers directly in Linux.

To make this work, you need the *.inf driver file. If your laptop dual-boots, this file is likely in the \Windows\System folder. It may also have come on a CD with the card, and is otherwise downloadable from the manufacturer's website.

Note

Downloadable hardware drivers often appear as *.exe files. Usually this is just a self-extracting archive. To pull the INF file out of the archive, you may need to run the program in Wine, Crossover Office, or Windows itself before using ndiswrapper to use the driver in Linux.


Once you have the INF file, open a shell as the SuperUser, and navigate to the directory where the INF file is. Run this command to confirm that ndiswrapper can identify the driver:

ndiswrapper  l <driverfilename>.inf 

You should see a message confirming that ndis installed, and the driver is present.

Now you need to make the kernel recognize the driver. This is done through modprobe.

modprobe ndiswrapper 

The final step is to add these two commands to your rc.local configuration file. The kernel will now load the driver each time at boot.

Finding an Access Point

Ideally with your drivers in place, you should now be able to scan the area for a nearby access point. If your wireless interface point is eth2, you can just type iwlist eth2 scan from the shell. You would then need to use iwconfig to configure your connection.

There is a KDE tool that can simplify this process, however. The Wireless Assistant will perform the scan and connect you. Download the Wireless Assistant SUSE Linux package from http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=/Network/wlassistant and install it through YaST. You can also use apt if you have the suser-guru repository in your sources.list.

Launch Wireless Assistant from the KDE Kicker menu, or run it from the shell with wlassistant. The first time, it checks for your active network card. The card name should appear in the Device line at the top of the Wireless Assistant screen. It will then scan the area for access points, and display the results of the scan in the main window. Look carefully, as you will also learn the quality of the wireless signal with a star ranking. The WEP column indicates whether a connection supports the relatively secure Wireless Encryption Protocol. This requires a password, but is still a big improvement over allowing open access to whatever comes across the network transom (including any passwords you may send out while you're surfing the Web).

Click the access point you want, and you will be prompted for the Root password on your system. Enter it, click OK, and you're connected.

Configuring Your Wireless Card

YaST can help you connect to your wireless network as well. If you know the network you want to connect to, using YaST will set things up for you. In YaST, go to Network Devices, then Wireless Network Card. Figure 12.9 will appear.

Figure 12.9. Configure your wireless card to connect to a stable network here.


At the top of the screen is the network Operating Mode. Nearly all the time, you want to choose Managed mode, as this is a connection with a wireless access point. An ad-hoc network is a peer-to-peer setup with no access point, and Master mode sets up your machine as an access point.

The next line indicates the name of the network you want to connect to. In wireless networking, access points are identified with an Extended Service Set Identifier (ESSID). You should enter the name of your network here, otherwise the card will select the first access point it finds.

The last section deals with authenticating yourself to the network. There are three types of wireless networks, "open" networks that are open to anyone (and that means anyone) without authentication. Generally speaking, you want to leave these networks to the bad guys who will invariably find them. WEP, or "shared key" authentication, is the prevalent, if not superior, option with many wireless networks. When severe holes were found in WEP, a new secure protocol was developed for wireless networks, WiFI Protected Access (WPA). This protocol is still not widely used, but is supported by the Linux kernel and SUSE Linux.

Select the appropriate protocol from the Authentication Mode drop-down menu, then define your pass-key using the mode buttons and the Encryption Key edit box. Selecting a passphrase is the best way to proceed, if you want to have more control over your security. If you select Passphrase, enter a word or a character string from which a key is generated according to the length previously specified. ASCII requests an input of 5 characters for a 64-bit key and 13 characters for a 128-bit key. For Hexadecimal, enter 10 characters for a 64-bit key or 26 characters for a 128-bit key in hexadecimal notation.

Tip*

Tips on creating passwords and passphrases are located in Chapter 19, "Managing Users, Managing Security."


You may keep up to four different keys to encrypt the transmitted data. Click Multiple Keys to enter the key configuration dialog. By default, this is set for 128-bit security, but you can lower the level to 64 bit here (not that you should).

In the list area at the bottom of the dialog, up to four different keys can be specified for your computer to use for the encryption. Press Set as Default to define one of them as the default key. Unless you change this, YaST uses the first entered key as the default key. If the standard key is deleted, one of the other keys must be marked manually as the default key.

You should now be successfully connected to your wireless network.



SUSE Linux 10 Unleashed
SUSE Linux 10.0 Unleashed
ISBN: 0672327260
EAN: 2147483647
Year: 2003
Pages: 332

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