Digging through some old box files I came across disks and print outs of code I wrote in the 1980s (mostly assembly language). One particular program is called NETSCOOP and acts as a protocol analyzer for the Z-NET. It scoops up packets from the network and displays them on screen after decoding source, destination and port information. Additionally it shows the packet contents.
Here are a couple of scans:
Local area network protocol analyzer which was filed 19 February 1987. There's another dated 22 October 1986 called Method and apparatus for a packet-switched network communications measurement matrix display. But that's still after NETSCOOP because I stopped working on it in June 1986. Even tcpdump dates to 1987.
So, this could be prior art for all those local area network protocol analysis patents. Any lawyers want to opine?