This recipe shows you the basics of working with Security-Enhanced Linux (SELinux), a kernel extension that adds an extra layer of security to your CentOS installation. Because it runs at the kernel level, SELinux can control access beyond the reach of the traditional filesystem permissions, including restricting running processes and other resources.

Unfortunately, some administrators disable SELinux because admittedly it can be a source of frustration. They're comfortable with the user/group/all and read/write/execute approach and suddenly find themselves at a loss when SELinux blocks something that seems as it should be available. However, the extra layer of security that SELinux provides is worth the effort of investigating such problems and adjusting its policies if necessary.