Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

We deployed a server application in .NET 4.0 that is going to run on Windows Server 2008 R2. Strangely, the clients cannot connect to the server given the server's IP and the server port.

I've ran wireshark diagnostics on the server computer and verified that the packets are arriving to the NIC without any issue so it seems Windows Server 2008 is the culprit here.

I've tried to temporarily disable the firewall and add the server port into inbound/outbound rule but it still doesn't solve the issue.

How can I solve this issue?

Edit: Sorry, bad choice of word. The server is not "rejecting" the packets, the server is just failing to respond.

share|improve this question
What's the server responding with? By saying 'rejecting', you're implying that the server is responding with TCP RST packets, but is that the case? Or is it just failing to respond? – Shane Madden Oct 25 '12 at 4:37
The application opens up a TCP socket and starts listening on it. When the client tries to send a packet, the application on the server's end never gets it. But when I ran wireshark and checked the TCP stream, the content definitely arrived to the server's NIC but the OS seems to be blocking it. – l46kok Oct 25 '12 at 4:46
Turn off all firewalling on the machine and see if the problem goes away. – David Schwartz Oct 25 '12 at 4:51
@DavidSchwartz I did exactly that and well, no luck D: – l46kok Oct 25 '12 at 4:51
Did you check if the server is replying to the packets? – David Schwartz Oct 25 '12 at 5:05
up vote 1 down vote accepted

My god, this was a pretty big gotcha for me. The server's NIC has two ip addresses and for Windows 2008, the inbound/outbound rule only applies for the IP that is closest to the default gateway.

I went ahead and made it so that the clients connect to the other server's IP and bam, everything works

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.