Sign Kicks All Players That Join A LAN World

Using the following command will kick any player that joins the game until the sign is destroyed:

/setblock ~ ~1 ~ standing_sign 0 replace {BlockEntityTag:{Text1:"[\"\",

{\"text\":\"\nNo Entry :\n\"}

,

{\"selector\":\"@p[name=!dagwoodland]\",\"color\":\"red\"}

]"}} in a command block.