PPTP Registry Entries

The following is a list of user-definable registry entries for PPTP, followed by explanations of those entries.

The following PPTP registry values are located in the following registry key:

By default, the following PPTP registry values are not created.

• AuthenticateIncomingCalls
  • Data type = REG_DWORD
  • Range = 0 or 1
  • Default = 0
  Set this parameter to 1 to force the PPTP protocol to accept calls only from IP addresses listed in the PeerClientIPAddresses registry value. If AuthenticateIncomingCalls is set to 1 and there are no addresses in PeerClientIPAddresses, then no clients can connect.
• PeerClientIPAddresses
  • Data type = REG_MULTI_SZ
  • Range = the format is a valid IP address xx.xx.xx.xx
  The server only accepts PPTP calls from a client that has an IP address in the list of IP addresses included in this registry value. This value is only relevant if the AuthenticateIncomingCalls registry value is set to 1.

The following PPTP registry values are located in the following registry key, where <AdapterName> is the name of a network adapter:

• DontAddDefaultGateway
  • Data type = REG_DWORD
  • Range = 0 or 1
  • Default =1
  When PPTP is installed, a default route is created for each LAN adapter. For example, if you have two LAN adapters - one for Internet access and one for the corporate LAN, you have a default routes for each adapter. This value disables the default route on the corporate LAN adapter.
• PPTPFiltering
  • Key = <AdapterName>\Parameters\Tcpip
  • Data type = REG_DWORD
  • Range = 0 or 1
  • Default = 0
  This parameter controls whether PPTP filtering is enabled on a per-adapter basis. If this value is set to 1, then the adapter only accepts PPTP connections. This reduces exposure to attacks if the adapter is connected to a public network such as the Internet.
• PPTPTcpMaxDataRetransmissions
  • Key = Tcpip\Parameters
  • Data type = REG_DWORD
  • Range = 0 to 0xFFFFFFFF
  • Default = 9 (Windows NT 4.0) or 5 (Windows 2000)
  This parameter controls the number of times that a PPTP packet is retransmitted if it is not acknowledged. The value is set higher than the default TCPMaxDataRetransmissions value to prevent dead gateway detection from occurring on congested Internet links.