Good point, I should have been more careful about the terminology. My point was that it's possible to have UPnP configure a port to be translated for a particul

Good point, I should have been more careful about the terminology. My point was that it's possible to have UPnP configure a port to be translated for a particular host on the LAN but still have a firewall on the router blocking access to that port. Another reply to my comment suggests that at least some consumer routers open a firewall port up as well, meaning that UPnP is still a potential security hole on those routers. (This might actually be required by the IGD protocol spec for all I know, that would be unfortunate...)