Slackware Linux Essentials
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5.5 Wireless

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Wireless networking is still a relatively new thing in the world of computers, yet is -quickly catching on as more people begin to purchase laptops and want networking on the -go, without having to fool with some old twisted pair cable. This trend doesn't appear to -be slowing down. Unfortunately, wireless networking isn't yet as strongly supported in -Linux as traditional wired networking.

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There are three basic steps to configuring an 802.11 wireless Ethernet card:

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Hardware support for the wireless card
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Configure the card to connect to a wireless access point
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Configure the network
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5.5.1 Hardware Support

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Hardware support for a wireless card is provided through the kernel, either with a -module or built in to the kernel. Generally, most newer Ethernet cards are provided -through kernel modules, so you'll want to determine the appropriate kernel module and -load it through /etc/rc.d/rc.modules. netconfig may not detect your wireless card, so you'll probably need -to determine the card yourself. See http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/ for more -information on kernel drivers for various wireless cards.

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5.5.2 Configure the Wireless -Settings

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The vast majority of this work is done by iwconfig, so as -always read the man page for iwconfig if you need more -information.

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First, you'll want to configure your wireless access point. Wireless access points -vary quite a bit in their terminology, and how to configure them, so you may need to -adjust a bit to accommodate your hardware. In general, you'll need at least the following -information:

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The domain ID, or name of the network (called the ESSID by iwconfig)
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The channel the WAP uses
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The encryption settings, including any keys used (preferably in hexadecimal)
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A NOTE ABOUT WEP. WEP is quit flawed, but it's much better than nothing. If you wish a -greater degree of security on your wireless network, you should investigate VPNs or -IPSec, both of which are beyond the scope of this document. You might also configure your -WAP not to advertise its domain ID/ ESSID. A thorough discussion of wireless policy is -beyond the scope of this section, but a quick Google search will turn up more than you -ever wanted to know.

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Once you've gathered the above information, and assuming you've used modprobe to load the appropriate kernel driver, you can edit rc.wireless.conf and add your settings. The rc.wireless.conf file is a bit untidy. The least effort is to -modify the generic section with your ESSID and KEY, and CHANNEL if required by your card. -(Try not setting CHANNEL, and if it works, great; if not, set the CHANNEL as -appropriate.) If you're daring, you can modify the file so that only the necessary -variables are set. The variable names in rc.wireless.conf -correspond to the iwconfig parameters, and are read by rc.wireless and used in the appropriate iwconfig commands.

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If you have your key in hexadecimal, that's ideal, since you can be fairly confident -that your WAP and iwconfig will agree on the key. If you only -have a string, you can't be sure how your WAP will translate that into a hexadecimal key, -so some guesswork may be needed (or get your WAP's key in hex).

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Once you've modified rc.wireless.conf, run rc.wireless as root, then run rc.inet1, again as root. You can test -your wireless networking with standard testing tools such as ping, along with iwconfig. If you have a -wired interface you may wish to use ifconfig to turn those -interfaces off while you test your wireless networking to ensure there's no interference. -You may also want to test your changes through a reboot.

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Now that you've seen how to edit /etc/rc.d/rc.wireless for -you default network, let's take a closer look at iwconfig and see how it all works. This -will teach you the quick and dirty way of setting up wifi for those times when you find -yourself at an Internet cafe, coffee shop, or any other wifi hot spot and wish to get -online.

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The first step is to tell your wireless NIC what network to join. Make sure you -replace “eth0” with whatever network interface your -wireless card uses and change “mynetwork” to -the essid you wish to use. Yes, we know you're smarter than that. Next you'll have to -specify the encryption key (if any) used on your wireless network. Finally specify the -channel to use (if needed).

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-# iwconfig eth0 essid "mynetwork"
-# iwconfig eth0 key XXXXXXXXXXXXXXXXXXXXXXXXXXX
-# iwconfig eth0 channel n
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That should be all on the wireless end of things.

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5.5.3 Configure the Network

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This is done in the exact same way as wired networks. Simply refer to earlier sections -of this chapter.

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