Yes, take your pick from ArmA 2
or Operation Arrowhead
. You would need to use CAA1
which should include sahrani. You need to put the mission in your MPMissions folder inside the ArmA 2 directory.
To play in LAN obviously all your friends have to be on the same network, simply select LAN mode in mp lobby and create a game, select the sahrani map then the mission, and your good to go.