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Wifi at boot

August 7th, 2008 Leave a comment Go to comments

Some people may have noticed that wifi doesn’t exactly turn itself on until the user has logged in to the desktop. That’s a problem for some users. How is it a problem? It gets in the way of remote administration.

If I’m at work and am remotely logged in to my home PC (via SSH, for example) then there may come a time when I want to reset my PC. If my wireless does not turn itself on when the PC turns on then I end up with a PC turned on at home, not connected to the internet, and no one around to log in for me.

Note: In the following example, your wifi card may not be recognized as “wlan0″. Type “ifconfig” to see what yours may be. Substitute whatever yours is in place of wlan0.

How do you connect to a wireless access point from the command line?

First, you “turn on” your wireless card

sudo ifconfig wlan0 up

Now you should be able to

sudo iwlist wlan0 scan

which will show you all the wifi access points within range. The wifi card needs to know which access point to connect to. This is done by

sudo iwconfig wlan0 essid WhateverAPYouAreConnectingTo

and if it uses a (WEP) key then set the key

sudo iwconfig wlan0 key WhateverTheKeyIs

But you’re not connected yet. You need to establish the PC’s IP address within the network

sudo dhclient

and you’re set. You should see “bound to 192.168.x.x — renewal blah blah blah” as the last line. Test the connection

ping google.com

and you see that packets are being transmitted and received.

So how do you set that automatically? Stick the commands in your /etc/rc3.d/S99rc.local file, at the very bottom.

...blah blah...
esac

# Added on this date to get wifi on bootup
ifconfig wlan0 up
iwconfig wlan0 essid WhateverMyAccessPointIsCalled
iwconfig wlan0 key WhateverMyKeyIs
dhclient

Now every time you restart your computer, your computer will be connected to the network before you even log in.

Take a look at this article for some explanation of what rc.d scripts do.