Well folks, this one has been puzzling me for weeks. I have read RFCs and many documents, but it appears that no one can give me a definate.

Background

Trying to determine the level of close-wait states on an Internet0based application. Netstat -na is very good for getting the basic info. Now I can monitor the states with a script. However, while I cannot terminate the sockets, I can restart the application, causing all sockets to resolve themselves. However, before I start monkeyong around with this, I need to get definitive answers as the the cause of close-wait states and instead of writing a script to restart an application after a number of close-wait state appear, perhaps a script to prevent them would be better?

Below is a simple diagram taken from the RFC on TCP based connections:


TCP A TCP B
1. ESTABLISHED ESTABLISHED
2. (Close) FIN-WAIT-1 --> <SEQ=100><ACK=300><CTL=FIN,ACK> --> CLOSE-WAIT
3. FIN-WAIT-2 <-- <SEQ=300><ACK=101><CTL=ACK> <-- CLOSE-WAIT
4. (Close) TIME-WAIT <-- <SEQ=300><ACK=101><CTL=FIN,ACK> <-- LAST-ACK
5. TIME-WAIT --> <SEQ=101><ACK=301><CTL=ACK> --> CLOSED
6. (2 MSL) CLOSED

Can anyone provide me with a few guidlines on which way to go? Or, has something already been created to do the job.

By the way, I also tried tunning the tcp values of the OS which has made little to no difference.

In reply to Smartly dealing with CLOSE-WAIT states by sdyates

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