pam_usb provides hardware authentication for Linux using ordinary USB Flash Drives.
Install the AUR package.
Setting up pam_usb requires the following, once pam_usb is installed:
- Set up devices and users
- Configuring PAM for system authentication
Setting up Devices and Users
Once you have connected your USB device to the computer, use pamusb-conf to add it to the configuration file:
# pamusb-conf --add-device MyDevice
Please select the device you wish to add. * Using "SanDisk Corp. Cruzer Titanium (SNDKXXXXXXXXXXXXXXXX)" (only option) Which volume would you like to use for storing data ? * Using "/dev/sda1 (UUID: <6F6B-42FC>)" (only option) Name : MyDevice Vendor : SanDisk Corp. Model : Cruzer Titanium Serial : SNDKXXXXXXXXXXXXXXXX Volume UUID : 6F6B-42FC (/dev/sda1) Save to /etc/pamusb.conf ? [Y/n] y Done.
MyDevice can be any arbitrary name you would like. Also, you can add as many devices as you want.
Next, configure users you want to be able to authenticate with pam_usb:
# pamusb-conf --add-user root
Which device would you like to use for authentication ? * Using "MyDevice" (only option) User : root Device : MyDevice Save to /etc/pamusb.conf ? [Y/n] y Done.
Check the configuration
You can run
pamusb-check anytime to check if everything is correctly worked. This tool will simulate an authentication request (requires your device to be connected, otherwise it will fail).
# pamusb-check root
* Authentication request for user "root" (pamusb-check) * Device "MyDevice" is connected (good). * Performing one time pad verification... * Verification match, updating one time pads... * Access granted.
Setting up the PAM module
To add pam_usb into the system authentication process, we need to edit
The default PAM configuration file should include the following line:
auth [success=2 default=ignore] pam_unix.so try_first_pass nullok_secure
Change it to:
auth sufficient pam_usb.so auth [success=2 default=ignore] pam_unix.so nullok_secure
sufficient keyword means that if pam_usb allows the authentication, then no password will be asked. If the authentication fails, then the default password-based authentication will be used as fallback.
If you change it to
required, it means that both the USB flash drive and the password will be required to grant access to the system.
Now you should be able to authenticate with the relevant USB device plugged-in.
* pam_usb v.SVN * Authentication request for user "root" (su) * Device "MyDevice" is connected (good). * Performing one time pad verification... * Verification match, updating one time pads... * Access granted.
su fails to use pam_usb
If you set:
auth sufficient pam_usb.so
su prompts for a password, and does not use pam_usb, add the same line at the beginning of
/etc/pam.d/su. This may be required for other pam-aware applications as well.