=====Secure Server Build=====

====Execshield====

Enable ExecShield Protection Against Buffer Overflows

Open your /etc/sysctl.conf file:
  # vi /etc/sysctl.conf

Add the following lines:

 
  kernel.exec-shield = 1
  kernel.randomize_va_space = 1
 
Save and close the file. First line will enable ExecShield protection and second line will enable random placement of virtual memory regions protection. To load in sysctl settings, enter:
  # sysctl -p
  
reference:
http://www.cyberciti.biz/faq/what-is-rhel-centos-fedora-core-execshield/