@arstechnica UPnP stands for "Universal Penetrate and Pwn." It was chiefly built so that Microsoft DirectPlay could work "seamlessly" by poking holes in your firewall without asking you. It should be disabled wherever you see it.
You should also go in to your router and block port 3544 so that Teredo (UPnP v2) can't tunnel IPv6 through your firewall.