[$] Using systemd for more secure services in Fedora

The AF_PACKET local privilege escalation (also known as CVE-2016-8655) has been fixed by most distributions at this point; stable kernels addressing the problem were released on December 10. But, as a discussion on the fedora-devel mailing list shows, systemd now provides options that could help mitigate CVE-2016-8655 and, more importantly, other vulnerabilities that remain undiscovered or have yet to be introduced. The genesis for the discussion was a blog post from Lennart Poettering about the RestrictAddressFamilies directive, but recent systemd versions have other sandboxing features that could be used to head off the next vulnerability.