Skip to content

How to connect to a wireless network from the Ubuntu command line

Why use a friendly GUI when there’s cryptic shell commands out there?

Phoenix Coffee offers free wireless access without an access key and they broadcast their ESSID. Here’s how I connect:


$ sudo iwlist eth1 scan # eth1 is my wireless card.
eth1      Scan completed :
          Cell 01 - Address: 0A:1D:19:15:C2:C1
                    ESSID:"bestcoffee"
                    Mode:Master
                    Channel:5
                    Frequency:2.432 GHz (Channel 5)
                    Quality=88/100  Signal level=-44 dBm  Noise level=-81 dBm
                    Encryption key:off
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                              9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s
                              48 Mb/s; 54 Mb/s
                    Extra:tsf=0000003befa89182

That scan lists every available access point. The important piece of information to extract here is the ESSID. Now I set my wireless card up to connect to that ESSID:

$ sudo iwconfig eth1 essid "bestcoffee"

And finally, I tell my card to request an IP address from the router:

$ sudo dhclient eth1 # gimme an IP address plz!
There is already a pid file /var/run/dhclient.pid with pid 6911
killed old client process, removed PID file
Internet Systems Consortium DHCP Client V3.0.6
Copyright 2004-2007 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
wmaster0: unknown hardware address type 801
Listening on LPF/eth1/00:1c:bf:96:7e:21
Sending on   LPF/eth1/00:1c:bf:96:7e:21
Sending on   Socket/fallback
DHCPREQUEST of 192.168.1.112 on eth1 to 255.255.255.255 port 67
DHCPACK of 192.168.1.112 from 192.168.1.1
bound to 192.168.1.112 -- renewal in 251284 seconds.

I can type these three commands way faster than waiting for the GUI to fire up. Here they are again, without all the output:

$ sudo iwlist eth1 scan
$ sudo iwconfig eth1 essid "bestcoffee"
$ sudo dhclient eth1

Sometimes, I need to connect to a network with a hidden ESSID. That’s just as easy. I just configure the ethernet card to connect to anything:

$ sudo iwconfig eth1 essid any # any is a keyword, not the name of an ESSID.

Finally, some networks require an access key. Sometimes, people can give you the human-friendly version, and you can type that in like this:

$ sudo iwconfig eth1 key s:password # translates to the hex for me.

Note the s: in front. That translates what I type into the hex jibberish.

Other times, people insist on giving you the goofy string of hex digits, so you can set it like this:


$ sudo iwconfig eth1 key ACDB-1234-1234-EFG2

Posted in Ubuntu, Unix.

By matt
June 13, 2008

Comments

Viewing 13 Comments

 
close Reblog this comment
Powered by Disqus · Learn more
blog comments powered by Disqus