Linux has the ability to display protocol statistics with netstat -s. The output looks something like:
7487 times unabled to send RST due to no memory TCPDSACKIgnoredOld: 817 TCPDSACKIgnoredNoUndo: 7246527 TCPSpuriousRTOs: 4583587 TCPSackShifted: 15825 TCPSackMerged: 455582
But these are accumulated over all networking interfaces. Is there a way to see these statistics per interface? I know that there are packet level statistics in
/sys/class/net/$INTERFACE/statistics, but have not been able to find any protocol related ones.