2013-01-12

Setting up fprintd with pam on Linux Mint 14

Last time, I talked about how to go about setting up fingerprint-gui on Linux Mint. This time, I will write about an alternative approach to getting your fingerprint reader working with Linux Mint, which has a more pleasing user experience.

Installing the necessary packages

Before we begin, we need to add a few packages:

sudo apt-get install fprintd libpam-fprintd

Mint comes preconfigured to use fprintd with PAM out of the box, so there is no need to fiddle with configuration files. All you need to do now is to enroll the fingerprints.

Enroll fingerprints from the graphical interface

Open up the main menu and find the app called User Accounts. Unlock it by clicking on the button in the top-right corner. Click the button labeled "Disabled" next to the fingerprint label (note: it doesn't look like a button at first sight, but it is clickable.

You will be asked to choose which finger you want to enroll and then you will swipe it five times. After you are done, you will be able to log in with your fingerprint, use your fingerprint with command-line commands and graphical apps that require administrative privileges, and pretty much anywhere where you needed your account password before.

Enroll fingerprints from the command line

The command-line utility is called fprintd-enroll. Run that command in your terminal app, and swipe the finger you want to use for autentication five times. After each successful swipe, the tool will show a message that says "enroll-stage-passed".

branko ~ -> fprintd-enroll 
Using device /net/reactivated/Fprint/Device/0
Enrolling right index finger.
Enroll result: enroll-stage-passed
Enroll result: enroll-stage-passed
Enroll result: enroll-stage-passed
Enroll result: enroll-stage-passed
Enroll result: enroll-stage-passed
Enroll result: enroll-completed

Comparison to fingerprint-gui

As I've said in the last article, fingerprint-gui just doesn't have the kind of user experience and streamlined integration that you get with this method. The method described in this article also doesn't need any PPAs. It just works with packages that are already there in the repositories.

A minor issue with fprintd as of this writing is the fact that the LED on the device won't light up when fingerprints are requested. In most cases, you will have other clues on your screen that tell you that you need to swipe, but it can be confusing in the login screen when the username field sort of becomes locked, and you are wondering what is going on.

The main disadvantage of fprintd over fingerprint-gui is inability to enroll more than one finger. For example, on my X220 convertible tablet, I find it inconvenient to use the right thumb when the computer is in tablet mode (and, therefore, the fingerprint reader is at the opposite side). However, because the integration is great, I find fprintd to be a good compromise.