Sending a TCP packet to localhost in an ASP.NET Page on Win 2008 R2

Question

We have a windows service running that listens on e.g. port 9999. Now we want to be able to send a TCP packet through an ASPX page to that service. Both the service and ASP.NET WebApp run on the same server.

The problem is that this works fine on my dev machine (without IIS though, through Visual Studio Web Server) and on our older Win 2003 Server machine. But it doesn't work on our new Win2008 R2 Server. The packet just won't arrive.

I'm absolutely clueless as to what the problem may be. A search in Google didn't help me as it seems I'm the only one wanting to send TCP packets through an aspx site.

What I have tried so far: 1) Changing the identity of the corresponding Application Pool 2) Disabled the Firewall 3) In web.config set the trust level to "Full" (which seems to be default anyways)

I'd appreciate any more hints!

Answer 1

And if you use software like TCPView and/or Wireshark do you see the connection being created and the packet being sent? The first step into solving this problem is finding out on 'which side' the cause lies.

It might also be useful to see the code you're using to build the connection and actually send the packet. Might give some clues as to what is going wrong :)

And last but not least, you say it works on your development machine with ASP.net WebDev server. Install IIS locally and try it again. Try to mimic the actual problem situation as best as you can (apart from OS-choice etc.).