Google has launched an application for the authentication code. Applications is named Google Authenticator can be used for various smartphone platforms.
By using this application you can secure your Google account from hacker attacks, code that frequently changes from your phone with your regular password to use.Only your phone and Google knows that the key needed to generate a sequence of code. It provides two-factor authentication, you need to know your password and have your phone.
Google Authenticator is an open source project, and establish open standards. This project provides a pluggable authentication (module PAM) which allows the authenticator to be used to log into a Linux system with no involvement from Google servers. Now Google Authenticator package is available on server repository ubuntu Oneiric Ocelot
Google Authenticator Package can be directly installed on ubuntu 11.10 Oneiric Ocelot by typing the command on terminal
sudo apt-get install libpam-google-authenticator
How to run and use Google Authenticator, on terminal type
after typing the above command then terminal displays QR code that you can scan using smartphone applications. You will also get some emergency code if you do not have your cell phone.
Now how to activate (PAM module) Google Authenticator for SSH login. you have to do is edit the file /etc/pam.d/sshd,add this line:
auth required pam_google_authenticator.so
Next, open /etc/ssh/sshd_config,change or add the ChallengeResponseAuthentication line so it reads:
Restart SSH to make the configuration change take effect:
sudo service ssh restartvia: tombuntu