Wireless Networking Basics - Setting up the Support Software
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Configuring the software is the tough part. This is where all the hard questions get asked.
Configuring the Linksys WMP11 for Windows
I was presented with this when I tried to configure my card:
The Linksys utility was looking for a service set identifier (SSID). The SSID is like a Windows workgroup name where if you connect to the right workgroup, you're in the right network. What I needed to do is create a default profile so that my computer knew what to do so I didn't have to reconfigure it on reboot.
Clicking on "Profiles" leads me to this:
I chose Expert Mode, because as in most installers, the wizards sometimes make assumptions on what you want.
I'm being asked for a few things here, and these are the essential settings to getting up and running.
In infrastructure mode, your computer is looking for a router or an access point. In ad-hoc mode, I would be using the wireless equivalent to a cross-wired ethernet cable. This mode allows two computers to talk directly to each other without the use of an access point or a router. This is great for a quick transfer of files if you don't have a burner or USB memory key handy.
The transfer rate lets us choose a speed for the wireless card to transmit. Leave this at auto and let the software decide what's good for you. I've seen my transfer rate change once in a while, but it is almost always at 11 Mbps.
The channel is similar to the channel button on cordless phones and hand-held two-way radios. Setting your channel to one that is already in use by another network can cause lots of connectivity problems as they will interfere with each other. Its a very good idea to keep the distance between channels as much as possible. Channels 2, 6, and 11 are usually a good choice.
Clicking on "Network Setting" gave me a screen which would look familiar if you've ever set up a network before:
Here I'm being asked if I'm using the dynamic host configuration protocol (DHCP) or if I'm using a static IP address for my computer, and if I have specific domain name service (DNS) servers to use.
Selecting "Obtain an IP address automatically" sets my card in DHCP mode, meaning my router will be giving me an IP address. This will be enough for most users, and beginners should definitely be using this. Choosing 'Use the following IP address' gives you a lot more flexibility, but you have to know a bit about networking to use it properly. Use this if you're an advanced user or your network administrator tells you to. You will need your IP address, your gateway, and the subnet mask of your network.
Using DHCP to get an IP address also allows you to use it to get your DNS server addresses. DNS servers are the servers that computers go to when they have "http://ocaddiction.devhardware.com" and need "64.43.71.141". Without DNS servers, we would need to memorize numbers in order to go to our favourite websites. If you have your own DNS server, you can type it in, but I recommend leaving the DNS setting to the default of 'Obtain DNS server address automatically.'
Finally, I had to set up the Windows network for File and Printer Sharing. It took five minutes, and works just like any other wired network.
Linux wireless setup from the command line
Most distributions do this in pretty much the same way. You may find that some of the files are in different locations, but the concept is essentially the same. I'll use my examples from my Red Hat boxes, but you should be able to do this in any Linux distribution. I'll admit that I did use Red Hat's Internet Connection Wizard, but it didn't work and it forgot to set the routing tables, which I'll talk about later. Command line methods are guaranteed to work and after you use the command line, you can make a small script to do stuff like this for you. I have two or three scripts like that, made with tinkering with the command line tools. Besides, who needs a GUI anyway?
You need your root password and the name of the device that iwconfig said had the wireless extensions, and the MAC address of your card.
Red Hat keeps a list of startup scripts for setting up devices on boot. The networking scripts are kept in /etc/sysconfig/network-scripts. If you already have a wired ethernet connection, you'll probably find a file called ifcfg-eth0.
Red Hat was nice enough to put in a comment saying that if we needed help with documentation, we should look in a file called sysconfig.txt. Its really wordy, but it does have a section on wireless networks. Since on my Red Hat 8 box, the wireless card is eth1, I copied the file for eth0, edited it, and called it ifcfg-eth1. All the info we put in a Windows configuator, like the SSID, and the mode, go in this file. Managed mode is the Linux way of saying infrastructure mode.
When you're done, run ./ifup eth1. The ifup script does some magic for you, like setting up the DHCP client or manually setting the IP address. You can use ifconfig to see if your device was activated properly.
Great! eth1 has an IP address. Time to start surfin' the 'net, right?
The Linux kernel may not know how to use it yet. The kernel has internal routing tables, which we can change. If you have a wired ethernet device in your box as well as a wireless one, you may think that your wireless is working, but what you are really using is the other device. My Red Hat 9 box had this problem when I set it up because I had a USB ethernet attached to it.
As root, type route at a shell.
The default line tells me that the kernel is using eth0 instead of wlan0 for everything that doesn't have an IP address beginning with 192.168.81, 192.168.0, 169.254.0, and 127.0.0.1. That really means that all web surfing, downloading, etc goes through eth0. We need to change that with two route commands - one to delete the current route, and one to make a new one:
What I've done here is change the default gateway to 192.168.81.1, which is my wireless router's IP address. All web traffic should go there anyway, since wireless networks connect to the internet through the router or access point.
Next: Securing the Wireless Network >>
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