It's perfectly safe to try as long as you do not disable password logins. There are packages for several Linux distributions, with instructions here. I'll run through a source installation; don't worry, it's easy. In addition to your usual build environment, you need the development libraries for USB and PAM. Install these first, then grab the latest tarball from ThinkFinger, and unpack it thusly:

$ tar zxvf thinkfinger-0.3.tar.gz

Then run these commands to compile and install it:

$ ./configure  --with-securedir=/lib/security \
  --with-birdir=/etc/pam_thinkfinger
$ make
# make install
# modprobe uinput

# tf-tool --acquire
[...]
Please swipe your finger (successful swipes 0/3, failed swipes: 0)...

Snug your finger into the little indent above the scanner, and slowly draw your finger across the scanner. You need three successful scans. The scan will be stored in /tmp/test.bir. Now you can test it- run this command, and swipe your finger, again slowly:

# tf-tool --verify
Result: Fingerprint does match

Next: Logging In With Your Fingerprint »