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FWSM shows "TCP checksum incorrect"

When we setup a connection between two hosts we receive the message

"TCP checksum incorrect" , This is  between a settop box on the outside and a server inside the firewall. This STB used to communicate with the server on port 443 which is NAT-en to port 12697.

With a new settop box image which uses on the inside and outside port 12697 we receive this TCP checksum incorrect on the Firewall with wireshark.

Strange is that on the outside of the firewall we see an MSS of 1460 and on the inside it is 1380 (don't know if there is a relation with this and the issue we have)

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FWSM shows "TCP checksum incorrect"

Hi jkwakman

This could be a normal message in wireshark if the capturing interface is doing TCP offloading in it's driver. See wireshark FAQ http://www.wireshark.org/faq.html#q11.1

pato

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