To disable SElinux, the security system within centos, you need to modify the SElinux file. Reasons for wanting to disable SElinux, would be that your server is internal, and to configure each service is a waste of time. SELinux is good for machines that are facing the internet, within a De-militarized Zone.
The SELinux configuration file is located at
To disable SELinux go to the configuration file look for the following line
then change the line to
The above with take effect during the next reboot, but if you need the effect to be immediate you can disable SELinux immediately at the command line with the following command