Minecraft wiki entry for Nether_survival, associated text: Netherrack can be acquired in the Overworld from ruined portals. This can be smelted, and the resulting nether bricks crafted into nether brick fence. Three stacks of netherrack yield exactly a full stack of fences. Since nether brick fences are blast resistant and can also be seen through, they make a good option for windows and/or perimeters when building your first shelter around your portal. A quick way to do this recipe is as follows: