I know how to set up the fingerprint reader for my Thinkpad X220 in Ubuntu 11.10.

My question is: Is it possible to only use the fingerprint reader at the LightDM-Login and not when typing "sudo ..." in the terminal or starting an application that needs superuser rights?

  • What do you want to use for authentication for sudo and others? Password, something else, or nothing? The first two require changes to /etc/pam.d/sudo, the last to /etc/sudoers. Could you show contents of the relevant file in your system? – taneli Apr 1 '12 at 11:16
  • I would like to use password authentication all the time except at LightDM login. My /etc/pam.d/sudo: #%PAM-1.0 @include common-auth @include common-account @include common-session-noninteractive My /etc/sudoers: Defaults env_reset Defaults secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" # User privilege specification root ALL=(ALL:ALL) ALL # Members of the admin group may gain root privileges %admin ALL=(ALL) ALL # Allow members of group sudo to execute any command %sudo ALL=(ALL:ALL) ALL – lebenlechzer Apr 9 '12 at 23:09
  • Sorry, my post again, more readable: I would like to use password authentication all the time except at LightDM login. My /etc/pam.d/sudo: link My /etc/sudoers: link – lebenlechzer Apr 9 '12 at 23:15

This solution assumes that you only have (or had) to modify /etc/pam.d/common-auth to make fingerprint reader work.

  • Make a copy of the file sudo cp -p /etc/pam.d/common-auth /etc/pam.d/common-auth-finger and make the necessary changes to that file instead (if you use pam-auth-update or some other automated tool, just let it make changes, and swap the files afterwards)
  • In /etc/pam.d/lightdm replace the line that has @include common-auth to read @include common-auth-finger

This should be all that is needed. If you had changed pam configuration in a different way, please tell how.

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