Date: Wed, 26 Feb 2003 00:49:18 -0800 (PST) From: Doug Barton <DougB@FreeBSD.org> To: Charles Sprickman <spork@inch.com> Cc: Jonathan Lemon <jlemon@flugsvamp.com>, stable@FreeBSD.ORG Subject: Re: LAST_ACK timeout Message-ID: <20030226004737.N903@znfgre.tberna.bet> In-Reply-To: <20030226033845.V98344@shell.inch.com> References: <200302250317.h1P3HTtJ056208@mail.flugsvamp.com> <20030226033845.V98344@shell.inch.com>
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On Wed, 26 Feb 2003, Charles Sprickman wrote:
>
> On Mon, 24 Feb 2003, Jonathan Lemon wrote:
>
> > In LAST_ACK state, the machine should keep retransmitting the FIN
> > until it gets an ACK from the peer, or the connection times out,
> > which should take roughly 8 minutes. If the connections stay around
> > forever, then something is broken.
>
> The one thing all connections had in common was that they were outbound to
> MSN.com. I believe that to scale their junk software up, everything is
> behind load-balancers, which can make things interesting if the LB doesn't
> do things "correctly".
I agree on the need for LB's to do things right, but they aren't just for
helping MS software. :)
> > ISTR someone mentioning that things were working as expected in the
> > latest -stable, which version are you using?
>
> This particular box is 4.6.2-p2. Since rebooting with IPFilter in place,
> I'm not seeing it anymore. So either MSN fixed something or IPFilter is
> masking the problem (or both). Somewhere in my Google-ing, I found people
> claiming that LAST_ACK can sit around for days if the other end doesn't
> respond. If this were less of a harried situation, I would have tcpdumped
> some traffic to see if we were actually retransmitting the FIN.
>
> Got a PR or anything referencing the possible problem?
I'm curious about whether keepalives help this situation. What does
net.inet.tcp.always_keepalive say?
Doug
--
"The last time France wanted more evidence, it rolled right
through Paris with a German flag." - David Letterman
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