Re: [lwip-users] closesocket problem (lwip_close)

[David Empson]

"Adam Fullerton" <address@hidden> wrote:
> I am using a web browser on a PC to look at pages served by Webio
> through lwIP's socket API. There is a checksum offload engine in use
> in the lwIP ethernet interface, so this could be a problem.
>
> How do you know which packets have bad check-sums from frame 9
> onwards? When I was developing the COE code Wireshark would turn
> packets with bad checksums red. Which frames from 192.168.243.12 have
> bad checksums?

There is a preference in Wireshark for whether it validates the TCP 
checksums. Mine was off and I assume that is the default because I don't 
remember changing it.

Edit > Preferences > Protocols > TCP > Validate the TCP checksum if possible
(with a similar one for UDP)

You may have fixed your checksum offload's implementation of IP header 
checksums (which Wireshark does validate by default), but still have a 
problem with offload of TCP and UDP checksums.