In minecraft servers how do you lock doors?

I'm in a server and there's group with good items and I took a fire aspect sword now there door says can open need permission some s*@t like that, well how do I lock it where only my allies and groups can come in without any plugins or mods or anything that involves downloads just commands I want.

Sorry to say, but I think that the only way to lock a door (i.e just a normal door that only specific people can open) is only obtainable by installing the plugin 'Lockette'.
Another way to lock a door will be constructing a redstone contraption, so that a hidden lever is the only way to open a door.
I think that the owner of this server has permissions so that only he, and other high ranks, can lock doors, whereas other people like you, can't. He/she probably has Lockette, but permissions are blocking you from accessing it.