netdev - Re: [PATCH -next] net: tcp: move to timewait when receiving data post active-close

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Message-ID: <1447861591.22599.157.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Wed, 18 Nov 2015 07:46:31 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Florian Westphal <fw@...len.de>
Cc:	netdev@...r.kernel.org, marcelo.leitner@...il.com
Subject: Re: [PATCH -next] net: tcp: move to timewait when receiving data
 post active-close

On Wed, 2015-11-18 at 16:36 +0100, Florian Westphal wrote:

> Yes, but we kill the socket.
> 
> I should have added
> 
> 0.400 `ss -nito state time-wait`
> 
> as last line...
> 
> Before patch: no output
> after patch: tw socket shown.
> 
> The on-wire behavior doesn't change unless further packets arrive.
> Old behaviour: more RST
> New behaviour: acks+tw timer restart

Just add few more incoming packets to the packetdrill test then ?

Also, is your customer really _not_ using TCP timestamps ?

This is kind of a requirement for port reuse anyway.

Anyway, having a TIMEWAIT setup after sending a RST makes little sense
to me.

When a RST packet is sent, the remote peer will forget everything about
this previous connection, and another connect() might reuse the tuple
and I do not think we should forbid this. Normal PAWS checks were
invented for a good reason.

RFC 1122, 4.2.2.13 can be interpreted in very different ways.

Please show us real issue your customer has.

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