Tcp listen accepts multiple simultaneo​us connection​s even when closed

Question

LV 6.0.2, win 2k
I am trying to set up a server that will recieve data from multiple clients. If I set up a TCP listen vi on the server, then I have found that any (or the same) client can open multiple connections on this port and send data to it even though the server has only called the TCP listen VI once and only has a reference for the first connection. The subsequent connections seem to be accumlating in the port buffer and the data can in fact be retrieved with subsequent calls to TCP listen on that port regardless of whether the client has closed the connection long ago and forgotten about the transaction.
This could perhaps be considered either a feature or a bug. For me it is undesirabl
e. I would prefer that attempted connections to the server were rejected if the server is not actually actively listening on the port. Otherwise clients can easily flood the port.
Is there some way to control this behaviour, or perhaps a completely different approach? or is there some way to control the port settings such as buffer size or max number of connections allowed, and a way to clear the buffer without processing all the connections?
Thanks in advance for any thoughts.

Answer 1

Thanks for the comments.
I don't seem to get the same behaviour you describe.
When you say 'if the server closes the connection after reading the first request, then it will not process the rest of the requests waiting in the queue'. I find that after the server closes the connection (with TCP close connection) then there can still be a huge backlog of connections to the same port (requests) which are still waiting to be processed. Another call to TCP listen retrieves one of the old ones, it doesn't wait around for a legitimately new request from a client.
Where you say 'When you leave the connection open on the server side, you can receive multiple commands this way, but it also blocks other clients from connecting until the curre
nt client disconnects'. This is in fact my main difficulty. Even with a connection held open other clients (or the same client) CAN make other connections and send data through that connection. This then backs up if the server is not processing them faster than recieving them.
I've attached vi's which should demonstrate the issue.
I couldn't check your vi's. I'm missing the EOC error.vi and one other I think. Ultimately I hope to do something similar with multiple open connections, but still need the server to be able to refuse connections if it wants to. Something I don't seem to be able to do. The connections just keep coming regardless of how the server is set up.
Thanks again.
Steve
Attachments:
server.vi ‏229 KB
client.vi ‏28 KB