RE: [lwip-users] TCP client side problems using netconn api

[Ben Bobbitt]

Here's the pcap file from wireshark.  If you look, you can see a few successful 
tcp sessions that close without issue and then in frame 158 you'll see the ack 
sequence issue and the resulting FIN, ACK retries repeatedly from the server.

In capturing this for you, I notice that I did not correctly report that the 
Client FIN, ACK is also the wrong (?) seq number, not as I wrote below, but:

Server  FIN, ACK   seq 433 ack 70
Client   ACK       seq 70  ack 433     < - note the ack # is == seq prior
Client   FIN, ACK  seq 70  ack 433 <--- this seq is still 433
Server ACK         seq 434 ack 71

The client (lwIP ) is the .106 IP, the server (apache on linux) .103





-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Kieran Mansley
Sent: Wednesday, April 15, 2009 2:41 AM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] TCP client side problems using netconn api

On Wed, 2009-04-15 at 00:10 -0400, Ben Bobbitt wrote:
> In a connection that isn’t going away properly – and results in a
> system that I can’t get usable without a reset:
>
>
>
> Server  FIN, ACK   seq 433 ack 70
>
> Client   ACK            seq 70   ack 433     < - note the ack # is ==
> seq prior
>
> Client   FIN, ACK  seq 70  ack 434
>
> Server ACK           seq 434 ack 71

I'm not sure what your problem is, but it's not the ACKs in the above
sequence: the "Client FIN, ACK" acknowledges the "Server FIN, ACK" even
though the "Client ACK" on its own didn't.

As you're able to get a wireshark capture of the problem I'd be
interested to take a look at the pcap.

Kieran



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tcpclosefail.pcap
Description: tcpclosefail.pcap