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Date:      Sun, 2 Jan 2005 14:42:41 +0100
From:      "Norbert Koch" <>
To:        <>
Subject:   HTTP, FIN_WAIT_1 and ppp hangup delay
Message-ID:  <000001c4f0d0$ee7ed5d0$fe78a8c0@k62300>

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For connecting to internet I am using
One of my FreeBSD (4.10) boxes uses kernel sppp,
the other one is configured with userland ppp.

My isp charges the connection time in
seconds resolution so I configured a very
short hangup delay of 25 seconds after
inactivity. This works fine for udp connections
and also for smtp/pop/nntp, but not for http.

After closing a web browser (I use konqueror
or opera) "netstat -nf inet" shows
a lot of active or closing connections.
So I reduced all "net.inet.tcp.*" times I could
find to not more than 15 seconds. This
helped, but still from time to time I see
a connection slowly dying in FIN_WAIT_1 state.

That means, ppp disconnects and immediately
dials again, disconnects again after 25 seconds
without any traffic and dials again and so on... 
for about 3 minutes.

I read through the tcp codebut,
well, can't say, I really look through it.
May be, there is still a hard-coded timeout, I
could manipulate through an additional sysctl?

I am rather sure that it is a problem of the
tcp protocol (or its misuse), and not an isdn
or ppp problem.

(BTW, the windows software Fritz!ISDN, shipped with
 the AVM isdn card, does quite a good job with
 short hangup delays, but I don't know how)

Any ideas? May be there is a way to RST a tcp connection
in the ppp-down script? Or perhaps some stateful ipfw rule?

Thank you,

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