I have an experimental TCP/IP stack running under Windows XP. This stack bypasses the Windows TCP/IP stack using a LSP and a NDIS IM. I now have a requirement to provide a proxy service for this to support other platforms that want to use the experimental stack. The proxy must be transparent to the clients (no client configuration). I want to run this proxy service in user mode where I have a TCP connection towards the client using normal Windows TCP/IP and a TCP connection the other way through the experimental stack. Once connected this way, the proxy just reads/writes between the two. The problem I am wrestling with is how to take an incoming packet from the client that is destined to some address/port and redirect it to my proxy while still maintaining the knowledge of the original destination address/port, so the proxy can forward the packets to the proper destination. I would appreciate any ideas on this. Thanks...