How to find all possible small boxes e.g. 2x2x2 and their overlaps within a bigger NxNxN cube?

Given an NxNxN cube (image), how can I find all the 2x2x2 boxes within the NxNxN cube? of course if N is even, we can find 2x2x2 boxes without overlapping, but when the N is odd, there is overlapping between some of the 2x2x2 boxes found in the bigger cube.

So,

1- How can I find all the non-overlapped 2x2x2 boxes in a bigger NxNxN cube where N is even?

input: NxNxN cube output: all the possible non-overlapped 2x2x2 cubes.

2- How can I find all the overlapped 2x2x2 boxes in a bigger NxNxN cube where N is odd? This time, the overlapped areas in the 2x2x2 boxes should be zero in second (or more) visits; i.e. each overlapped area should be visited (counted) once not more.

input: NxNxN cube output: all the possible overlapped 2x2x2 cubes with zero values for the overlapped voxels in 2nd or more visits.