RedirectConnections Method of the IFWXSession Interface

Article
08/13/2010

The RedirectConnections method enables connections by using a local, internal Microsoft Firewall service address.

Syntax

HRESULT RedirectConnections(
  [in]            LPSOCKADDR ConnectAddresses[],
  [in]            DWORD ConnectAddressLength,
  [in]            DWORD dwNumberOfAddresses,
  [out]           LPSOCKADDR InternalAddress,
  [in, out]       LPDWORD InternalAddressLength,
  [in]            LPSOCKADDR ProxyExternalAddress,
  [in]            DWORD ProxyExternalAddressLength,
  [in]            INT Protocol,
  [in]            DWORD dwFlags,
  [in]            REFGUID ProtocolGuid,
  [in, optional]  IFWXSessionFilter* pSessionFilter,
  [in, optional]  IUnknown* punkContext,
  [out]           IFWXFirewallAction* FirewallActionArray[]
);

Parameters

ConnectAddresses
Pointer to an array of pointers to sockaddr structures that contain the addresses to which the client connections will be redirected.
ConnectAddressLength
Length, in bytes, of the addresses pointed to by the ConnectAddresses parameter.
dwNumberOfAddresses
Number of addresses in the ConnectAddresses array.
InternalAddress
The socket address on the Forefront TMG internal interface where the client should connect. This value is updated by the Firewall service.
InternalAddressLength
Length, in bytes, of the InternalAddress parameter.
ProxyExternalAddress
Pointer to a sockaddr structure that contains the Forefront TMG computer's external address used for the connection. This is useful in the case of multihomed Forefront TMG computers. Requesting a specific address ensures that a secondary connection uses the same IP address as the primary connection. This parameter can be NULL, defaulting to INADDR_ANY and 0 (any port).
ProxyExternalAddressLength
Length, in bytes, of the ProxyExternalAddress structure.
Protocol
Protocol flags. This parameter can have the following flag values:

Value Meaning

FWX_PROTOCOL_TCP

The connection will use a TCP socket.

FWX_PROTOCOL_UDP

The connection will use a UDP socket.

Value	Meaning
FWX_PROTOCOL_TCP	The connection will use a TCP socket.
FWX_PROTOCOL_UDP	The connection will use a UDP socket.

dwFlags
Connection flags. This parameter can be a combination of the following values:

Value	Meaning
FWX_FLAG_ALLOW_MULTIPLE	By default, a single outbound connection is expected. If this flag is specified, multiple connections to the same address will be possible.
FWX_FLAG_TIMEOUT	The client is expected to use the permission shortly after the call. If the client does not make the connection, the permission automatically expires.
FWX_FLAG_NO_KERNEL_MODE	Each connection goes through user-mode code, regardless of whether kernel mode could be used for the connection.
FWX_INCREASE_RECEIVE_BUFFER	The receive buffer will be increased to 64 kilobytes. This flag should be set to prevent packet loss if high-bandwidth packet bursts occur in a secondary UDP connection.

ProtocolGuid
GUID that identifies the protocol that the connection is part of.
pSessionFilter
Pointer to the IFWXSessionFilter interface. Use with the punkContext parameter to receive an event of type fwx_EstablishedConnection (as defined in the FxwFirewallEventType enumerated type) from the Firewall service.
punkContext
Provides user context information regarding the connection. Use with the pSessionFilter parameter to receive an event of type fwx_EstablishedConnection from the Firewall service. This parameter can be NULL. Specify NULL if notification of fwx_EstablishedConnection events is not required, or if you do not need to pass any context information.
FirewallActionArray
Pointer to an array of IFWXFirewallAction interface pointers. The array is filled with pointers to IFWXFirewallAction interfaces to the firewall action objects created by this call. The array contains dwNumberOfAddresses pointers.

Return Value

This method returns S_OK if the call is successful; otherwise, it returns an error code.

Remarks

This method is intended for use by filters that act as an application proxy that has to establish secondary connections and give the same address as the primary connection for the secondary connection.

Filters for Forefront TMG Client and Firewall Client computers and for SecureNAT clients usually use AllowFutureConnect instead.

Calling this method causes all filters that are registered for connect events on the appropriate port to be notified. If no data filters are installed, a kernel-mode NAT redirection may result.

Requirements

Server	Requires Windows Server 2008 R2 or Windows Server 2008 x64 Edition with SP2.
Version	Requires Forefront Threat Management Gateway (TMG) 2010.
Header	Declared in Wspfwext.idl.
DLL	Requires Wspsrv.exe.