If you have the hardware, the cables, and four to twelve friends who still love the "point-and-click" gunplay of the golden era, setting up this offline LAN is the single best weekend gaming project you can undertake. The internet is temporary. True LAN glory is forever.
This is the most authentic way, but it requires a bit of elbow grease. The Steam version of MW3 no longer supports native LAN out of the box due to the deprecation of SteamWorks matchmaking for this title. call of duty modern warfare 3 lan multiplayer offline