Additional Security Features and Tools
Oracle Linux offers additional features and tools to augment the built-in operating system security controls. Whether it makes sense to implement these features depends on security requirements, configuration support, and compatibility with your application stack.
SELinux
Developed initially by the U.S. National Security Agency, SELinux adds additional layers of security beyond the basic UNIX Discretionary Access Controls (DAC) mechanisms. Specifically, SELinux adds functionality to support Mandatory Access Controls (MACs) and Role-Based Access Control (RBAC). SELinux mediates access controls according to vendor-provided policies, enforcing access decisions in the kernel.
By default, SELinux uses a policy called targeted, which isolates targeted processes to an operating domain and other processes to an unconfined domain. Use the sestatus command to show whether SELinux is running, the current mode, and the policy in use:
# sestatus
SELinux status: enabled
SELinuxfs mount: /selinux
Current mode: enforcing
Mode from config file: enforcing
Policy version: 24
Policy from config file: targeted
In some classified environments, site security policy may require the use of the SELinux mls policy, which supplies stringent Multi-Level Security (MLS) protection. MLS configurations typically require site and security-specific MAC labeling, which entails extensive customization.
Be sure to confirm support and compatibility of SELinux with the application stack. See the Security-Enhanced Linux User Guide for more details.
Linux Containers and Control Groups
Available in Oracle Linux 6 with the Unbreakable Enterprise Kernel, Linux Containers (LXC) provide a way to isolate a group of processes from others on a running Oracle Linux system. Linux Containers are a lightweight operating system virtualization technology built on Linux resource management control group (cgroup) capabilities and resource isolation that is implemented through namespaces. The "Containers on Linux" blog article by Wim Coekaerts introduces LXC functionality. The OTN article "How I Used CGroups to Manage System Resources in Oracle Linux 6" explores how cgroups can give administrators fine-grained control over resource allocations, making sure that critical workloads get the system resources they need.
For more information, see the Linux Containers chapter of the "Oracle Linux 6 Administrator's Solutions Guide.