Subj : Re: Closing tcp socket connections
To   : comp.programming
From : Alex Fraser
Date : Mon Aug 15 2005 02:58 pm

"Martin Hierholzer" <mhier@web.de> wrote in message
news:ddi105$lvc$1@sagnix.uni-muenster.de...
> I have a problem closing tcp network server sockets. I have written a
> (single threaded) server which is running on Linux (2.6.12-gentoo-r6) and
> a client which should run on Linux and Windows.
> The protocol between client and server is very simple, for every data
> packet sent by the client a new connection will be opened, the client
> will send its data and the server sends a reply and should close the
> connection.

This is very inefficient, it would be better to maintain connections.

> For testing stability, I send these small packets as fast as I can, so
> many packets arrive per second.
> To close the connection, the server makes calls to shutdown and close on
> the appropriate socket:
[snip code]
> But the connections seem to stay open even after these calls. Running
> netstat even immediately after cancelling the test client shows a lot of
> connections to my server, with state TIME_WAIT.

The TIME_WAIT state exists to drain "stray" packets; it is perfectly normal.
In particular, it does not indicate a problem with your code.

Stare at a TCP state transition diagram until you understand it :).

Alex

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