A TCP packet was rejected because it has an invalid sequence number or an invalid acknowledgement nu...

Kevin_27C · ‎03-27-2014

Dear All,

We have installd cisco ASA 5540 along with AIP-SSM-40 Module as our perimeter device. I was troubleshootig an Microsoft ISA proxy server issue when i found this error message occuring frequently

A TCP packet was rejected because it has an invalid sequence number or an invalid acknowledgement number.

I could see that these error messages appear in the external NIC of my ISA server ( with a private IP) installed inside the LAN. What i want to understand is how to block this message from appearing at the cisco ASA perimeter level. Any help here would be highly appreciated.

Joe Doran · ‎03-27-2014

The log output contains a logging message identifier. You can turn off the individual log message, but I would take reservation in doing so. I would try to make the traffic that is causing the message stop if possible so that if a similar situation happens in the future you get log messages about it.

%ASA-6-XXXXXX <--XXXXXX is the logging message id.

Disable it by:

no logging message XXXXXX