pam_usb
pam_usb provides hardware authentication for Linux using ordinary USB Flash Drives.
It works with any application supporting PAM, such as su and login managers (GDM, KDM).
Contents
Installation
Install the pam_usbAUR package.
Configuration
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've 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.
Note that MyDevice
can be any arbitrary name you'd 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 /etc/pam.d/system-auth
The default PAM configuration file should include the following line:
auth required pam_unix.so nullok_secure
Change it to:
auth sufficient pam_usb.so auth required pam_unix.so nullok_secure
The 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.
$ su
* 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.