Re: [lwip-users] Unusual termination of a TCP connection.

[Roger Cover]

Greetings,

In the Wireshark capture that I sent in my original post, the data sent from 
the server is ACKed by the same packet that contains the FIN. The lwIP 1.3.1 
server responds to this packet with a RST packet. I am curious why lwIP 1.4.1 
responds this way when lwIP 1.2.0 responds with ACK+FIN instead. Why are the 
two different?

Regards,
Roger
-----Original Message-----
From: lwip-users [mailto:address@hidden On Behalf Of goldsimon
Sent: Wednesday, September 28, 2016 1:22 PM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] Unusual termination of a TCP connection.

A RST is sent when lwip knows that one of the two sides has not read (or
packed) all data that has been sent. This is what standard socket stacks would 
do also.

Simon

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Am 28. September 2016 7:32:05 nachm. schrieb Roger Cover <address@hidden>:

> Greetings,
>
> I have a server application using lwIP 1.4.1. When I use a Python 
> program to connect to my server, the server always terminates the TCP 
> connection with a RST instead of a FIN packet. The RST appears to be 
> negatively impacting the performance of my communications. I have 
> attached a Wireshark capture of the traffic in the attached file 
> lwIP141.pcapng. In this file my server is at address 192.168.0.175.
>
> I previously implemented a server using the lwIP 1.2.0 library (about 
> a decade ago), and did not encounter this problem. The attached file 
> lwip120.pcapng is a Wireshark capture of the same Python program 
> communicating with the old lwIP 1.2.0 server. In this file my server 
> is at address 192.168.0.175. Using lwIP 1.2.0 the TCP connection 
> terminates normally with a FIN, FIN+ACK, ACK set.
>
> Does anyone have any insight into why the RST is being issued? Is 
> there anything I can do to eliminate this problem? I look forward to your 
> reply.
>
> Regards,
> Roger W. Cover
> Spectral Instruments, Inc.
> 420 N. Bonita Ave.
> Tucson, AZ 85745
> 520-884-8821 ext. 144
>
>
>
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