If you have just installed an Ubuntu and install some new application such as SSH server (which Ubuntu didn't ship with by default). And you want to make it start upon system reboot.
In normal cases like Fedora or CentOS or Redhat, we can always use the chkconfig to to the job.
But how can we do it in Ubuntu?
Easy. Just install "sysv-rc-conf" package using apt-get.
Just enter the menu as below and select which run levels and services you want to start in one single menu.
> sudo sysv-rc-conf