How to bring down a socket on a windows machine?

Question

I have a application which I suspects to get into problems because network nodes closes its sockets to various other servers it communicates to. I would like to mimic that behaviour by shutting down one or severel connections that can be seen in netstat. I'm not an expert in networking on OS level, so this question may be stupid, if so do you have any other suggestion on how to mimic the situation?

Answer 1

Before attempting to simulate the problem, you can diagnose the situation with certainty by using Wireshark or, on *nix, tcpdump. You should be able to capture the traffic and observer whether one of the server(s) is sending you a RST or not.

If you are receiving RST then this may be due to the servers themselves (time-outing and closing the connection while waiting for you to send them a response or data, or closing the connection because of server bugs or load limits), to your ISP's network equipment, or to your own network equipment (e.g. your wireless link going up and down.)

Disconnecting your router, network cable or wireless interface can simulate to various degrees connection issues that you can encounter at any time when talking to your servers. Disconnecting your PC's network cable should simulate a forceful closing of the connection with RST, whereas disconnecting a cable between you and the internet, but not the cable that directly connects your PC (e.g. disconnecting the cable between your router and your cable/DSL modem, or disconnecting the cable/DSL modem from the cable company's cable/telco's wall jack) will allow you to simulate timeout conditions.

Answer 2

You can use TCP View. You can view all the connections from your machine to another, or within the same machine. You can close a connection, thus breaking the connection.