Fingerprint login on Linux Mint streamlines authentication for both login and privilege escalation tasks, but its success depends on device compatibility and proper configuration. Supported fingerprint readers integrate smoothly with the system, while unsupported hardware may require additional troubleshooting or lack Linux driver support entirely.

Check Device Compatibility

Device compatibility is the main factor determining whether fingerprint login will work. Linux Mint relies on the fprintd framework, which supports a wide range of fingerprint readers. To verify compatibility, identify your device and check it against the official list.

Step 1: Identify your fingerprint device using lsusb. This command lists all USB devices and their IDs.


lsusb

Step 2: Locate the fingerprint reader in the output and note its vendor and product ID (the format is usually xxxx:yyyy).

Step 3: Visit fprint supported devices and search for your device ID to confirm support. If your device is not listed, check the unsupported devices page for additional information.

If your hardware is unsupported, Linux Mint may not be able to use the fingerprint reader. Some users have reported partial success with community drivers or by compiling custom firmware, but these approaches require advanced troubleshooting and are not guaranteed.

Install Required Packages

Supported devices work best using the fprintd and libpam-fprintd packages, which handle fingerprint enrollment and authentication. Additional libraries may be needed for some hardware models.

Step 1: Update your package list to ensure you get the latest versions.


sudo apt update

Step 2: Install fprintd and libpam-fprintd to enable fingerprint management and authentication.


sudo apt install fprintd libpam-fprintd

For some devices, you may also need to install libfprint-2-2 and libfprint-2-tod1:


sudo apt install libfprint-2-2 libfprint-2-tod1

These libraries provide additional driver support for newer fingerprint readers.

Configure PAM for Fingerprint Authentication

Linux Mint uses the Pluggable Authentication Module (PAM) system to manage authentication methods. By updating PAM settings, you can allow fingerprint authentication for login and sudo operations.

Step 1: Run the PAM authentication update tool to enable fingerprint support.


sudo pam-auth-update

Step 2: In the interactive menu, make sure "Fingerprint authentication" is selected. Use the Space bar to toggle selection, then press Tab to highlight "Ok" and Enter to save changes.

This step tells the system to prompt for fingerprint scans during login and sudo operations, in addition to passwords.

Enroll Your Fingerprint

Enrolling a fingerprint associates your biometric data with your user account. You can enroll multiple fingers for convenience or redundancy.

Step 1: Start the enrollment process for a specific finger using fprintd-enroll. Replace [finger-name] with a valid finger identifier (e.g., right-index-finger):


fprintd-enroll -f right-index-finger

Available finger names include:

  • left-thumb
  • left-index-finger
  • left-middle-finger
  • left-ring-finger
  • left-little-finger
  • right-thumb
  • right-index-finger
  • right-middle-finger
  • right-ring-finger
  • right-little-finger

The prompt will guide you through the scanning process. Follow on-screen instructions to complete enrollment.

Step 2: Test your fingerprint enrollment with:


fprintd-verify

If the verification succeeds, your fingerprint is ready for use in authentication scenarios.

Fingerprint Login at the Display Manager (Login Screen)

By default, Linux Mint uses LightDM as its display manager. Fingerprint login support at the login screen depends on both hardware compatibility and PAM configuration. If your home directory is encrypted with eCryptfs, you must use your password for the initial login, as fingerprint data alone cannot decrypt the encrypted folder.

To enable fingerprint login for the display manager:

  • Ensure fprintd and libpam-fprintd are installed.
  • Confirm that "Fingerprint authentication" is enabled in pam-auth-update.

For systems where fingerprint login is not desired for the initial login (e.g., with encrypted home directories), you can customize the LightDM PAM configuration to require passwords at login while still allowing fingerprint authentication for sudo and privilege escalation.

Step 1: Back up the existing LightDM PAM file:


sudo cp /etc/pam.d/lightdm /etc/pam.d/lightdm.bak

Step 2: Create a custom LightDM PAM configuration (for example, using vi or nano):


sudo vi /etc/pam.d/lightdm-custom

Paste the following content, which prioritizes password authentication at login:


#%PAM-1.0
auth    requisite       pam_nologin.so
auth    required        pam_unix.so
auth    optional        pam_ecryptfs.so unwrap
auth    optional        pam_gnome_keyring.so
account required        pam_unix.so
session required        pam_limits.so
session required        pam_env.so readenv=1
session required        pam_env.so readenv=1 user_readenv=1 envfile=/etc/default/locale
session required        pam_unix.so
session optional        pam_ecryptfs.so
session optional        pam_gnome_keyring.so auto_start
session optional        pam_systemd.so

Step 3: Replace the default LightDM PAM file with your custom configuration:


sudo ln -sf /etc/pam.d/lightdm-custom /etc/pam.d/lightdm

This configuration ensures password authentication is required at login, but fingerprint can still be used for sudo and other privilege escalations.

Troubleshooting Common Issues

Some users encounter "No devices available" or similar errors during enrollment. These issues usually indicate either missing drivers or unsupported hardware.

  • If you see Impossible to enroll: GDBus.Error:net.reactivated.Fprint.Error.NoSuchDevice: No devices available, double-check device support and make sure all required packages are installed, including libfprint-2-2 and libfprint-2-tod1.
  • If your device is not supported by fprintd, research community drivers or alternative projects like open-fprintd, but success is not guaranteed.
  • For some models, downloading or compiling third-party drivers may resolve the issue. Refer to device-specific forums or AskUbuntu threads for guidance.
  • Always restart your system after major authentication or driver changes to ensure new settings take effect.
  • If you encounter issues with the keyring asking for a password after login, this is a known quirk in some Linux Mint versions and may require additional configuration of the GNOME Keyring or PAM files.

Alternative: Graphical User Management

On some systems, you can enroll fingerprints using the graphical Users settings:

  • Open Settings → Users.
  • Select your user account and look for the Fingerprint Login option.
  • Follow the prompts to scan and register your fingerprint.

This method is less flexible than the command-line approach and may not be available on all editions or with all hardware.

Security Considerations

Fingerprint authentication speeds up login and sudo operations, but it is not as secure as strong passwords. Biometrics can be compelled or spoofed in some scenarios. For systems with sensitive data, consider using fingerprint login for convenience but retain password authentication for critical actions. Disk encryption with LUKS or eCryptfs still requires a password at boot or initial login.

Fingerprint login in Linux Mint simplifies authentication when your hardware is supported and properly configured. Always verify device compatibility, install the right packages, and adjust PAM settings to match your security needs.