Open /etc/inittab file, enter:
# vi /etc/inittab
Find the line that read as follows:
Change it as follows:
Save and close the file. Reboot system to test new changes:
By default SSH is not configured to run on startup. This means you will have to activate the service every time before being able to use SSH on the CentOS server.
To enable this to come back up after reboot run the following command.
chkconfig sshd on
This can be applied to any service you want to run on boot. Once this is done restart the server and SSH will be started