@var{dev} is an NBD device.
@table @option
+@item --object type,id=@var{id},...props...
+Define a new instance of the @var{type} object class identified by @var{id}.
+See the @code{qemu(1)} manual page for full details of the properties
+supported. The common object type that it makes sense to define is the
+@code{secret} object, which is used to supply passwords and/or encryption
+keys.
@item -p, --port=@var{port}
The TCP port to listen on (default @samp{10809})
@item -o, --offset=@var{offset}