I have a Windows Server 2008 R2 SP1 box with IIS 7.5.7600.16385 installed.

I have HTTP Keep-Alives switched off. Each time a web-request is made the connection is terminated.

I get the following packet trace:

enter image description here

I can see a FIN,ACK going from the client to the server, but none transmitted in the opposite direction.

If I try this from other machines with a supposedly identical configuration the FIN, ACK is transmitted in both directions.

I can't work out what the difference is? Is there any way of configuring this behaviour?

  • Does the symptom present when HTTP keep-alive is enabled?
    – Greg Askew
    Jan 24, 2013 at 12:13
  • No - because the connections aren't closed. If I forcibly exit the process I get a RST transmitted by the application. Jan 24, 2013 at 12:57
  • Seems like you may have answered your own question. Why are you disabling HTTP keep alive? If you want to mitigate the performance impact of connection and resource exhaustion, lower the connection timeout. Apache for example, uses a timeout of 15 seconds, compared to IIS default timeout of 120 seconds.
    – Greg Askew
    Jan 24, 2013 at 13:12
  • Check the flags on the "Application Data" packet, it will most likely have the missing FIN/PSH/ACK flags. Dec 4, 2013 at 20:09


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