First I had to ensure that the stock debian packages are available for installation: $ tail /etc/apt/sources.list deb http://archive.debian.org/debian etch main Install g++ and other dependencies $ apt-get install g++ libpam0g-dev Download google-authenticator source code: $ git clone https://code.google.com/p/google-authenticator/ $ cd google-authenticator/ $ ./configure && make && make install Then simply follow the instructions over at here