If you ask about WinpkFilter, then you can do it using the SendPacketToMstcp (if you want packet to be indicated from the name of another interface to the local TCP/IP stack) and SendPacketToNetwork (if you want it to be sent over the network from the interface different from received one). For both calls you should use corresponding network interface handles, both routines can be called with difefrent handles for the same packet any times you want. One note, if you want to bridge WAN interface you should also modify MAC addresses in the packet (this is point-to-point connection and MAC’s are used to distinguish different connections), otherwise NDISWAN won’t be able to find the corresponding link and may even crash the system…
