Configuring idle timeout for openSSH
We can configure idle timeout for ssh so that if there is no activity for given period, the user is automatically logged out. To configure idle timeout edit file '/etc/ssh/sshd_config'
ClientAliveInterval 300 ClientAliveCountMax 3
Using above configuration would disconnect client if there is no activity for 15 minutes.
One can refer to 'man sshd_config' for more information on above parameters.
Technique has been learned from http://www.cyberciti.biz/faq/linux-unix-login-bash-shell-force-time-outs/