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Date: Tue, 17 Oct 95 18:51 WET DST
From: aj@Ieunet.ie (Alan Judge)
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Subject: kern/784: 2.0.5-950622-SNAP tcp CLOSING/LAST_ACK problem (maybe fixed??)
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>Number:         784
>Category:       kern
>Synopsis:       TCP WWW connections seem to get stuck and never go away
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Oct 17 11:00:01 PDT 1995
>Last-Modified:
>Originator:     Alan Judge
>Organization:
Ieunet Ltd.
>Release:        FreeBSD 2.0-BUILT-19950612 i386
>Environment:

	We're running 2.0.5-950622-SNAP on a fairly busy web server,
	having just moved our primary web stuff over. 

>Description:
	The machine wedged earlier today, having running out of
	mbuf clusters (which I'll need to increase anyway).

	Having a snoop around, it would seem that some WWW connections
	with data queued are not going away after a dialup user
	hangs up.

	For example:
f072fc00 tcp        0   5270  192.111.39.241.80  138.220.76.189.130 CLOSING
f075c300 tcp        0  16384  192.111.39.34.8000 193.120.254.57.165 LAST_ACK

	Eventually this fills all the mbufs and everything stops.

>How-To-Repeat:

	Run a popular web server :-)  I'm sure that www.FreeBSD.org has
	hit similar problems.

>Fix:
	
	I've had a look at the sources and it would seem that keep alives
	have no effect here, as they are ignored if
		tp->t_state <= TCPS_CLOSE_WAIT

	However, from looking at the 2.1.0-951005-SNAP I see some
	interesting new code in tcp_timer.c.  Am I correct in
	thinking that the code that starts:
	       * Hack: if the peer is dead/unreachable, we do not
	       * time out if the window is closed.  After a full
	might fix the problem if pulled into my tcp_timers.c???
>Audit-Trail:
>Unformatted: