"tcpflags 0x18<PUSH,ACK>; tcp_do_segment" kernel messages

[Eygene Ryabinkin]

Bruce, good day.

Mon, Aug 06, 2007 at 11:41:12PM +0100, bruce at cran.org.uk wrote:
> I cvsupped my -CURRENT laptop last night and have been building ports
> today.  When I checked the dmesg there were lots of messages similar to:
> 
> TCP: [204.152.184.73]:21 to [10.0.10.13]:65159] tcpflags 0x18<PUSH,ACK>;
> tcp_do_segment: FIN_WAIT_2: Received data after socket was closed,
> sending RST and removing tcpcb

This was introduced in the /sys/netinet/tcp_input.c, 1.365.
The origin and need for the change was discuissed in
	http://lists.freebsd.org/pipermail/freebsd-net/2007-July/014804.html
(See http://lists.freebsd.org/pipermail/freebsd-net/2007-July/014808.html
for the explanation of what's going on).

If you were running -CURRENT on the same machine prior to CVSupping,
then you probably saw the 'Spurious RST' messages.  They were
provoked by the same situation.  The messages themselves are harmless,
they just telling us that some data was came in, but the listener
had already closed his socket, so he is not interested in the data
anymore.

Use sys.net.inet.tcp.log_debug to disable TCP stack debug output
and get rid of those.
-- 
Eygene