Many vendors use the Universal Plug and Play (UPnP) architecture to configure routers, firewalls, and other Internet Gateway Devices (IGDs). UPnP is essentially a set of protocols that define how a device should interact with a PC and how a PC should interact with a device.

UPnP devices advertise services that perform specific functions. For example, an IGD would expose a service that connects across a WAN such as the Internet and another service that enables a user to configure the device. These services announce themselves and are discovered by other devices on a network by using the Simple Service Discovery Protocol (SSDP). After an application has discovered a particular device and its services on a network, it can query and modify the service's properties or call the device service's functions.

Windows XP has native support for UPnP. If you install this support, you can control your UPnP-enabled network routers from the XP Network Connection folder's Internet Connection applet. Likewise, network-based media players (also known as media renderers), such as Roku Labs' SoundBridge, use UPnP to fetch lists of music to play from a PC running hosting software such as Windows Media Connect.

You can find more information about UPnP at the official UPnP Web site, http://www.upnp.org. And you can find information about the different properties that you can query and modify in an IGD at http://www.upnp.org/standardizeddcps/igd.asp.