HowTo: WPA with wpa_supplicant

**luca_linux** · September 22nd, 2006

Here was my first HowTo about this topic. It made a success, but now it's a bit out-to-date, as it was written for Hoary.
This stuff has started getting easier to configure since Breezy and now it's really very easy to have it work.
This HowTo will help you get WPA to work, no matter what wireless card you have. (This HowTo has been tested with an ipw2200).
So, let's start:

1) Open a terminal window and type:

Code:

wpa_passphrase your_ssid your_psk

Note: your_ssid is the name of your wireless network (a.k.a. SSID) and your_psk is the password you want to use to protect your network. (Look below for an example).

2) Now copy the psk string you got as output.

3) Type:

Code:

sudo gedit /etc/wpa_supplicant.conf

Then paste this as follow:

Code:

ctrl_interface=/var/run/wpa_supplicant
#ap_scan=2

network={
       ssid="your_ssid"
       scan_ssid=1
       proto=WPA RSN
       key_mgmt=WPA-PSK
       pairwise=CCMP TKIP
       group=CCMP TKIP
       psk=your_psk
}

Note: your_psk is the psk string you got from step 1.

Here is an example:

Code:

luca@laptop1:~$ wpa_passphrase mywlan thisisthepassword
network={
        ssid="mywlan"
        #psk="thisisthepassword"
        psk=b22ec921c254c73f99b31b76ff876692ecde36839a1f2d92150829e6afcb5515
}

The red string is what you have to paste into /etc/wpa_supplicant.conf as your_psk (without quotes obviously). So you'll have something like this:

Code:

ctrl_interface=/var/run/wpa_supplicant
#ap_scan=2

network={
       ssid="mywlan"
       scan_ssid=1
       proto=WPA RSN
       key_mgmt=WPA-PSK
       pairwise=CCMP TKIP
       group=CCMP TKIP
       psk=b22ec921c254c73f99b31b76ff876692ecde36839a1f2d92150829e6afcb5515

4) Save the file and close Gedit.

5) Now we have to make wpa_supplicant load when system boots, so go back to the terminal window and type:

Code:

sudo gedit /etc/network/interfaces

6) Add the following lines in the part regarding your wireless card, as in the example below:

Code:

pre-up wpa_supplicant -Bw -Dwext -ieth0 -c/etc/wpa_supplicant.conf
post-down killall -q wpa_supplicant

Note: "eth0" is your wireless device and "wext" is the driver; this is a kind of generic driver, so it should work with most wireless cards. If it doesn't, please try another driver, such as hostap, ndiswrapper, etc.
Here is an example:

Code:

iface eth0 inet static
address 192.168.1.15
netmask 255.255.255.0
wireless-essid my_essid
gateway 192.168.1.1
pre-up wpa_supplicant -Bw -Dwext -ieth0 -c/etc/wpa_supplicant.conf
post-down killall -q wpa_supplicant

7) Now run wpa_supplicant:

Code:

sudo wpa_supplicant -Bw -Dwext -i eth0 -c/etc/wpa_supplicant.conf

You should be online!

Troubleshooting:

You can run wpa_supplicant with -dd flag for a detailed debug output.

1) If you don't manage to connect to the AccessPoint, try to uncomment line 2 in /etc/wpa_supplicant.conf.
2) If that doesn't help, try change its value to 0 or 1.
3) If you get troubles while authenticating, try removing "RSN" and/or "CCMP" strings from /etc/wpa_supplicant.conf.

**yopnono** · September 24th, 2006

Only like to say that if you put the string in "/etc/network/interfaces" you will get an error if you try to reload the DHCP "sudo ifup -a --force"

I would go for a boot script in the /etc/init.d/your_own_script
And add it using

Code:

update-rc.d -f your_own_script start 40 S .

**luca_linux** · September 25th, 2006

If you use DHCP, your /etc/network/interfaces should look like the following:

Code:

auto eth0
iface eth0 inet dhcp
pre-up wpa_supplicant -Bw -Dwext -ieth0 -c/etc/wpa_supplicant.conf
post-down killall -q wpa_supplicant

Does this cause that error?

**yopnono** · September 25th, 2006

I know you should not enter the IP etc if using DHCP.
I did get an error

Code:

/etc/network/interfaces:12: misplaced option
ifup: couldn't read interfaces file "/etc/network/interfaces"

But what was because of this:

Code:

iface eth0 inet dhcp
auto eth0

Instead of:

Code:

auto eth0
iface eth0 inet dhcp

Strange this only happen if I enter the pre-up/down to the interface file

**yopnono** · September 25th, 2006

Another thing is that if you use the interface file and you dis/enable you network interfaces, it over writes the interface file.

**matthewboh** · September 25th, 2006

I am so close - I can almost taste it, but still not having luck. Can someone direct me?

I am running a LAMP server with a Linksys card running the Broadcom chipset. It can see the access point, but it won't hook up correctly. Here's the output of iwlist

Code:

eth0      Scan completed :
          Cell 01 - Address: 00:0C:41:D0:46:A0
                    ESSID:"matthewboh"
                    Protocol:IEEE 802.11g
                    Mode:Master
                    Channel:6
                    Encryption key:on
                    Bit Rates:54 Mb/s
                    Extra: Rates (Mb/s): 1 2 5.5 6 9 11 12 18 24 36 48 54 
                    Quality=100/100  Signal level=-145 dBm  
                    IE: WPA Version 1
                        Group Cipher : TKIP 
                        Pairwise Ciphers (1) : TKIP 
                        Authentication Suites (1) : PSK  
                    Extra: Last beacon: 270ms ago

and here's what the iwconfig brings back

Code:

eth0      IEEE 802.11b/g  ESSID:"matthewboh"  Nickname:"Broadcom 4318"
          Mode:Managed  Frequency=2.484 GHz  Access Point: Invalid   
          Bit Rate=11 Mb/s   Tx-Power=19 dBm   
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

The contents of the wpa_supplicant.conf

Code:

# Minimal /etc/wpa_supplicant.conf to associate with open
#  access points. Please see 
#  /usr/share/doc/wpasupplicant/wpa_supplicant.conf.gz for more complete
#  configuration parameters.

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0

eapol_version=1
ap_scan=1
fast_reauth=1

### Associate with any open access point
###  Scans/ESSID changes can be done with wpa_cli
# network={
#         ssid=""
#         key_mgmt=NONE
# }


# reading passphrase from stdin
network={
	ssid="matthewboh"
	proto=WPA RSN
	key_mgmt=WPA-PSK
	pairwise=CCMP TKPI
	group=CCMP TKPI
	psk=c43ae013621f4aa1db2d1127664349f425a2852c352c2c1d6913bfb056736b8d
}

**luca_linux** · September 25th, 2006

@ mattewboh: Are you trying without any protection/encryption? Otherwise, could you post the output of

Code:

sudo wpa_supplicant -Bw -Dwext -i eth0 -c/etc/wpa_supplicant.conf -dd

?

**luca_linux** · September 25th, 2006

Originally Posted by yopnono

I know you should not enter the IP etc if using DHCP.
I did get an error

Code:

/etc/network/interfaces:12: misplaced option
ifup: couldn't read interfaces file "/etc/network/interfaces"

But what was because of this:

Code:

iface eth0 inet dhcp
auto eth0

Instead of:

Code:

auto eth0
iface eth0 inet dhcp

Strange this only happen if I enter the pre-up/down to the interface file

Yeah, that's a bit strange.

**matthewboh** · September 25th, 2006

It just comes back with

Daemonize...

**luca_linux** · September 25th, 2006

Originally Posted by matthewboh

It just comes back with

Daemonize...

Oh sorry, my mistake, I meant:

Code:

sudo wpa_supplicant -w -Dwext -i eth0 -c/etc/wpa_supplicant.conf -dd

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