firewalld
Fedora 18 uses firewalld instead of iptables as the default firewall service. Using firewalld will allow for changes to be made to policy without restarting the service. In addition, current status and changes will be available via D-Bus. This improves support for dynamic environments like libvirtd.
Secure Boot
UEFI Secure Boot will be supported in Fedora 18. This will allow Fedora to boot on systems that have Secure Boot enabled. Tools are available for administrators to create custom certificates to sign local changes to GRUB or the kernel.
rngd
Random number generation is improved by enabling rngd by default.
Secure Containers
Using SELinux and virt-sandbox, services can be run in secure sandboxes, even as root. The virt-sandbox-service package will create mount points and a libvirt container.
SELinux boolean renaming
In order to clarify the purpose of SELinux booleans, all settings that begin with "allow" will be renamed to reflect their domain. Existing policy booleans will continue to be supported.
SELinux Systemd Access Control
Support has been added to systemd to check unit files against SELinux settings before allowing a process to start or stop the service.
usermode
usermode, a wrapper to provide superuser privileges to unprivileged users, is being phased out in favor of polkit.
halt, poweroff, reboot Configuration Moved
The ability to use halt(8), poweroff(8) and reboot(8) commands by unprivileged users is now controlled using polkit, see the actions in /usr/share/polkit-1/actions/org.freedesktop.login1.policy . The PAM configuration files /etc/pam.d/{halt,poweroff,reboot} are no longer used and their content, if any, is ignored.