Dave's Tech Blog
A Third Eye on Technology

(Special thanks to this blog post for showing me how to get this working finally).

About 2 months ago or so I read the tutorial in the above link to help get my fingerprint sensor setup in Ubuntu.  The problem was that it left one simple instruction out:  Paste a line of  text AT THE TOP of a config file (and not at the bottom like I did).  The mistake has been corrected and I’m happy to say my finger print sensor is working in Ubuntu 9.04.  Based on the directions from the the link above, here’s how to set it up (these instructions are meant for version 9.04; see the above link for instructions for 8.04 and 8.10):

Step 1: Click Applications>Accessories>Terminal and paste in the following command:

sudo apt-get update && sudo apt-get install aes2501-wy fprint-demo libfprint0 libpam-fprint

Step 2: Still in Terminal, paste in the following text:

sudo gedit /etc/pam.d/common-auth

This will open a text file called common-auth in Gnome Text Editor.  (Here’s where I screwed up last time).

Step 3: If you want to use both the password and the fingerprint to authenticate (more secure) add at the bottom:

auth required pam_fprint.so

If you want to use either the fingerprint or the password to authenticate (i.e. completely bypass the password through the fingerprint) the following string must be placed at the top of the file:

auth sufficient pam_fprint.so

Once pasted, save and close the file.

Step 4: Press Alt-F2, type “fprint_demo” without the quotes and press enter.

This will launch the fingerprint utility that you can use to enroll the finger you wish to use for future authentications.

That’s basically it.  Special notes:

• If you happen to screw something up in the config file by mistake and lock yourself out of your PC by accident, you can boot into Recovery Mode from the GRUB boot menu to access a root command prompt and edit the above config file using nano (nano /etc/pam.d/common-auth).
• Not all login screens are compatible with this feature.
• To test your finger print in fprint_demo, click on the verify tab at the top and use the verify button to compare an enrolled fingerprint to another finger (or the same finger) and you’ll see the difference.

As of Ubuntu 9.04, I’ve noticed the following quirks:

• Often you will not see an on-screen prompt asking you to swipe your finger across the sensor if the system is waiting for it.  Examples include the login screen, running Update Manager or Synaptic Package Manager, and otherwise most other programs that required your password to run them.
• The only actual on-screen requests I’ve seen so far is when you are unlocking a screen-saver, or are running a program with sudo privileges in a terminal window.