Wifi on the Command Line

This article demonstrates how one can setup a fairly secure wireless connection using the GNU/Linux command line.

Before we get started though, I must say that dd-wrt makes for an interesting upgrade to many different kinds of routers. Even my Linksys WRT54Gv8, purchased in 2007, is supported by dd-wrt version 24 and above. This firmware provides everything from a telnet login to useage graphs to Quality of Service priority settings. If you're brave, as a faulty upload could brick your router, I recommend it!

The first step in setting up a wireless connection in linux is discovering what wireless hardware your computer has. Here, lspci is helpful. After installing this utility, I get the following results:

$ lspci
02:04.0 Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC (rev 01)

That's interesting; so I'm using an Atheros chipset for wireless on my computer. Sometimes lspci will find unknown hardware. Naturally if your wireless card is unknown it's not going to be very useful. If you find yourself in this situation, you may need to recompile your kernel with support for the wireless chipset according to it's documentation or simply install a distro specific program that can automatically set it up for you.

Once Linux recognizes your wireless card, we can use wpa_supplicant to translate with any WPA or WPA2 protocols in use by the router. As each wifi setup differs, I recommend to read the following man pages and use the information to setup your configuration file.

$ man wpa_supplicant
$ man wpa_supplicant.conf

Now to setup that configuration file. Remeber, your configuration file may be very different so please read those man pages!

vim /etc/wpa_supplicant/wpa_supplicant.conf

# Home sweet home network, featuring a WPA/WPA2 Personal connection!
network={
ssid="Protoss Pylon"
scan_ssid=1
key_mgmt=WPA-PSK # WPA/WPA2 Personal
psk="yaa123_3311" # Passkey
priority=1000
}

# This is a network block that connects to any unsecured access point.
# We give it a low priority so any defined blocks are preferred.
network={
key_mgmt=NONE
priority=-9999999
}

Once we have configured wpa_supplicant, we can run it in the background using the switches mentioned in the man pages.

# wpa_supplicant -Dmadwifi -iath0 -c/etc/wpa_supplicant/wpa_supplicant.conf &

Also, please remember that you must still run your DHCP client to request an IP address. wpa_supplicant just takes care of WPA encryption.

# dhcpcd ath0

I recommend reviewing your distro's documentation regarding setting up wifi automatically during boot as each seems to do things differently. Happy hacking from remote locations.