Specify client port (and IP) on NetTcpBinding

Question

Is it not possible to specify the local client port used for server calls via NetTcpBinding?

NetPeerTcpBinding support this - I find it hard to believe there's no way to specify the local port (and IP Address for that matter) on clients.

I need to be able to use port sharing and I can't do this if I don't know what port the client is listening on. I won't be able to share the port (and IP) with another client so it can connect.

The only work-around I found is something like this:

• Client A opens a connection to Server
• Server logs the IP and Port of Client A
• Server shares this info. with Client B
• Client B should be able to connect to Client A on specified IP and Port (in theory)

This is known as TCP/IP NAT hole punching I believe. Anyone with experience in this?

Answer 1

You probably don't understand the communication pattern with NetTcpBinding. It works this way:

1. The client opens connection to the server
2. Two-way communication: The client calls the server and gets the response over the same connection.
3. Duplex communication: The client calls the server. The server stores reference to the channel somewhere (you must implement this). Once the server wants to notify client about anything it takes stored channel and calls the client on the connection established by the client during its first call.

The server never opens connection to the client. The client doesn't expose any address with port for incomming communication. If you want to do that you must implement service on the client in the same way you did it on the server and you must manully send the address and port to the service exposed by the server.

The difference with NetPeerTcpBinding is that there is no real server and any client must be able to get incomming request. NetTcpBinding is for client-server scenarios where the server is the only peer able to process incomming requests. Because of that only the server needs to define an address and a port.