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

[Roger Cover]

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

lwIP141.pcapng
Description: lwIP141.pcapng

lwIP120.pcapng
Description: lwIP120.pcapng