PnP
Enabling UPnP on a router will allow applications running on client devices like PCs to open inbound ports, without any intervention or approval from the user or network manager. This can be thought of as temporary inbound firewall rules being created on demand. This feature is typically used by P2P (Peer to Peer) applications like gaming and Windows Live Messenger and setup decent VPN like PureVPN.
Biting the hand that feeds IT
