I'm not really sure how it happened, but after installing 14.04 LTS I couldn't connect to my network over wifi.

I ran the LTS install from my CDROM - it walked me through connecting to my wifi ap. The installer uses this to initiate apt-get to download additional packages. All went well.

When I log in I found that there was no wifi configured and was left with a relatively empty /etc/network/interfaces file. So maybe I did it wrong - *shrugs*. If you happen to know what I did wrong - I'd be grateful for the answer!

If you find yourself in this position then my condolences to you. Here's what worked for me...please note I'm assuming you need to use a passphrase.

1. Check how far your install got, type this into your console to check if you ended up with some configuration:

ls /etc/wpa_supplicant.conf

If you dont have that file like me - then this post might be useful - now check if wpa_supplicant is installed ... try..


If this doesn't return with some usage tips - then this post will not help you as wpa_supplicant is not installed. My fix relies on it's existence. You may want to troubleshoot that, or decide if you even need to use it.

However, if it does exist, then you ended up like I did. While you are staring at the usage tips - take note of the drivers section. It will look a little bit like this:

  nl80211 = Linux nl80211/cfg80211
  wext = Linux wireless extensions (generic)
  wired = Wired Ethernet driver
  none = no dirver (RADIUS server/WPS ER)

I can't tell you what driver is right for you, but wext is what worked for me.

2. I'm using a root session for brevity. If you choose not to do this - please use sudo on each line that requires access to /etc/:

sudo -i

3. back up the network interfaces configuration file (/etc/network/interfaces) and then edit it

cp /etc/network/interfaces /etc/network/interfaces.old
vi /etc/network/interfaces

Use nano or something other than vi if thats your thing. But make the file look like this..

auto wlan0
iface wlan0 inet dhcp
wpa-driver wext
wpa-conf /etc/wpa_supplicant.conf

If your don't want to use dhcp - swap that out on line 2 for 'static'. Just be sure to add an address netmask and gateway line. See the man page for more on that... Note that I chose the wext driver (see step 1). You might need to select a more appropriate value for wpa-driver.

4. Now create /etc/wpa_supplicant.conf using the wpa_passphrase tool:

wpa_passphrase "YOUR_SSID_GOES_HERE" "YOUR SECRET_GOES_HERE" > /etc/wpa_supplicant.conf
vi /etc/wpa_supplicant.conf

If not, your file will look something like this...


Note that the #psk line, is actually a comment to help jog your memory. I prefer to use a password manager, so I generally turf that line. I made my file look more like this...

    proto=WPA RSN
    pairwise=CCMP TKIP
    group=CCMP TKIP

..now would be a good time to consult the man page for wpa_supplicant, because what you see above is a very generic take on the possible settings. It will ask your wifi card to try WPA/WPA2 and AES or TKIP crypto. In particular, scan_ssid is what tells the tool if you intend to use hidden SSIDs or not. Keep it set as above if you are connecting to a publicly visible SSID.

Whats the deal with the hexified psk? Well, even if you use a passphrase, supplicant encodes that before sending over the airwaves. You are cutting out the middle man here by pre-enconding the passphrase.

Now try cycling your wifi adapter:

ifdown wlan0
ifup wlan0

Hopefully you saw something like...

Listening on LPF/wlan0/12:23:34:45:56:67
Sending on LPF/wlan0/12:23:34:45:56:67

Final confirmation with a ping to your wifi router should let you know that it worked or not. Oh before you bail, you might want to tidy up any cleartext passes in your ~/.bash_history (and don't forget to log out from root if you copied my second step when your done)