Informational

First, install the package:

$ sudo apt-get install libpam-radius-auth
That was pretty painless. Now let's configure it. First, let's tell pam_radius which radius server to talk to:

$ sudo vi /etc/pam_radius_auth.conf

Edit the line "other-server other-secret 3" replacing 'other-server' with the IP address or hostname of your radius server.

Edit your /etc/pam.d/sshd file and add the line:

auth       required     /lib/security/pam_radius_auth.so

Just above:

# Standard Un*x authentication.
@include common-auth

Now, you are ready to test. I recommend you run 'tail -f /var/log/auth.log' while you test.