If you use Ubuntu or Suse you probably already have Apparmor installed on your system, so take a moment and see how this software can help you.
And also if you don’t use these distributions, this article can be interesting if you are interested at the security of your Linux Box.
AppArmor (“Application Armor”) is a security module for the Linux kernel, released under the GNU General Public License. AppArmor allows the system administrator to associate with each program a security profile that restricts the capabilities of that program. It supplements the traditional Unix discretionary access control (DAC) model by providing mandatory access control (MAC).
It was included as of the 2.6.36 version of the mainline Linux kernel. Since 2009, Canonical contributes to the ongoing AppArmor development.