Are you seeing this message as part of a , or are you trying to set up split-screen play? Call of Duty: Black Ops II Security & Enforcement Policy
If you are looking for a specific file or code snippet, the text "OpenNet plugin loaded top" is most likely a debug output string indicating that a specific network modification was successfully injected into the game process with high priority. If you are writing a paper on this, focus your research on "Game Network Hooking," "Quake Engine Networking," and "DLL Injection Techniques." call of duty black ops 2 opennet plugin loaded top
If you want to read up on this: