It has been announced that Security-Enhanced Linux (SELinux) will now be available as an alternative security option to AppArmour in Ubuntu 8.04 “Hardy Heron”.

Security-Enhanced Linux (SELinux) is a Linux feature that provides a variety of security policies, including U.S. Department of Defense style mandatory access controls, through the use of Linux Security Modules (LSM) in the Linux kernel.

Here is How to install SELinux on Ubuntu 8.04 taken from the Ubuntu Wiki:

How To Install SELinux on Ubuntu 8.04 “Hardy Heron”

Installing SELinux in Hardy:

1. Update /etc/apt/sources.list by appending the following:
   • deb http://ppa.launchpad.net/ubuntu-hardened/ubuntu hardy main
   • deb-src http://ppa.launchpad.net/ubuntu-hardened/ubuntu hardy main
2. Update repo:
   • > apt-get update
3. Install updated packages:
   • > apt-get upgrade
   • These packages have SELinux support patches:
     • libpam0g
     • openssh-server
     • grub
     • login
4. Install selinux:
   • > apt-get install selinux
   • These packages will be removed:
     • apparmor
     • apparmor-utils
5. Reboot

If using aptitude instead of apt-get, you will need to manually remove apparmor and apparmor-utils, deselect selinux-policy-dummy, and then choose selinux-policy-refpolicy.