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Configuration Settings

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The behavior of the Control Point API and Device Host API can be modified by changing settings in the registry.

There are seven registry values that affect behavior:

  • DownloadScope
  • DeviceLifeTime
  • \UPnP Device Host\File Size Limit
  • \Windows\CurrentVersion\UPnP\File Size Limit
  • MaxCache
  • TTL
  • ReceiveScope

There are two registry values called File Size Limit, one for description documents and the other for responses that use Simple Object Access Protocol (SOAP).

The location of each of the seven values in the registry is as follows:

HKEY_LOCAL_MACHINE
   SOFTWARE
      Microsoft
         UPnPControl Point
            DownloadScope
         UPnP Device Host
            Devices
               DeviceLifeTime
            File Size Limit
         Windows
            CurrentVersion
               UPnP
                  File Size Limit
   SYSTEM
      CurentControlSet
         Services
            SSDPSRV
               Parameters
                  MaxCache
                  TTL
                  ReceiveScope

Registry Value Descriptions

The registry values are explained in the following list. Each registry value is a REG_DWORD (a 32-bit integer). The effect of each value is global.

DownloadScope

Specifies which IP addresses are valid for the device description document URL. If the IP address of the host that is specified in the description document URL is not within the scope specified by DownloadScope, that IP address is not valid and the device object will not be created.

The valid values are shown in the following table. The default value is 1.

Value of DownloadScope Meaning
0 Host's IP address must be a subnet address.
1 Host's IP address must be a subnet address or a private address which is one of 10.x.x.x, 192.168.x.x, 172.16.x.x (as specified by RFC 1918), or 169.254.x.x (as specified by RFC 3330).
2 Host's IP address must be a subnet address, private address, or an address that is within the time-to-live (TTL) hops from the control point.
3 Host's IP address can be any address.
>3 Same as that for the value 0.

 

DeviceLifeTime

Optional. Specifies a device's lifetime, in seconds, which overrides the value provided in the device's announcement message. If DeviceLifeTime is present, the value specified in the device's announcement is ignored and the registry value is used instead. This applies to all devices.

Valid values range from 900 through MAX_DWORD. The default value is 1800. If DeviceLifeTime is set to 0, the default value is used.

\UPnP Device Host\File Size Limit

Specifies the maximum size, in bytes, of each description document. This setting is not configurable in versions of Windows preceding Windows XP Service Pack 2. In the previous versions, this setting is hard-coded as 102400.

Valid values range from 10240 through MAX_DWORD. The default value is 102400.

\Windows\CurrentVersion\UPnP\File Size Limit

Specifies the maximum size, in bytes, of the SOAP response that is acceptable. This setting is not configurable in versions of Windows preceding Windows XP Service Pack 2. In the previous versions, this setting is hard-coded as 102400.

Valid values range from 10240 through MAX_DWORD. The default value is 102400.

MaxCache

Specifies the maximum number of entries allowed in the Simple Service Discovery Protocol (SSDP) cache.

Valid values range from 10 through 30000. The default value is 1000.

TTL

Specifies the time-to-live for an SSDP packet. That is, TTL specifies the number of hops allowed for a packet.

Valid values range from 1 through 255. The default value is 1.

ReceiveScope

Specifies which IP addresses are valid sources of a message. If an incoming message originates from an address that is not within the scope specified by ReceiveScope, the message is ignored. This setting is not configurable in versions of Windows preceding Windows XP Service Pack 2. In the previous versions, a message is accepted without regard to its source.

The valid values are shown in the following table. The default value is 1.

Value of ReceiveScope Meaning
0 Sender's IP address must be a subnet address.
1 Sender's IP address must be a subnet address or a private address which is one of 10.x.x.x, 192.168.x.x, 172.16.x.x (as specified by RFC 1918), or 169.254.x.x (as specified by RFC 3330).
2 Not used. If ReceiveScope is set to 2, the default value is used.
3 Sender's IP address can be any address.

 

Overview of UPnP Architecture