Re: TCP resets connection after 3rd ACK with win=0

[Eric Dumazet]

On Wed, 20 Feb 2008 14:42:16 +0100
Gergely Magyarosi <gergely.magyarosi@xxxxxxxxxxxx> wrote:

> Hi!
> 
> Thanks for the hint.
> It is rather difficult to switch to the newest kernel on this system. It 
> uses a lot of custom-made patches, which should be adapted to 2.6.24.
> So this will take quite some time.
> 
> Meanwhile, I was wondering if this RST is a result of the local 
> application closing the socket too soon.
> 
> In /net/ipv4/tcp.c: tcp_disconnect()
> 
> As I see, a RST is generated, when there is still something in the send 
> buffer when closing the socket.
> I'll try to get the app. developer's opinion.
> 
> The TCP stack, when I close the socket, and there is still data in the 
> send (or maybe even in the receive) buffer, sends a RST.
> Am I seeing this correctly?
>

If you close socket while some data is still in receive queue, tcp stack SHOULD send an RST

Key sentence in RFC 1122

    From 4.2.2.13: If such a host issues a CLOSE call while received data is still pending in TCP, or if new data is received after CLOSE is called, its TCP SHOULD send a RST to show that data was lost. 

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