Minecraft wiki entry for Safe_home, associated text: If you get lost in the Nether and have no choice but to start a new shelter there, or even if you just wish to try out Nether survival, your biggest problem is ghasts. They can fly through the air, shoot fireballs that explode on contact with the ground (although the explosion is fairly weak), and can spot you from 100 blocks away. Obviously, a simple fence won't suffice. The simplest solution is to build a roof over your entire living area, preferably fairly big, in case you feel like expanding your house later, and start building a house in it. The best material would be glass, as you can see through it and tell if any ghasts are nearby before leaving your dome, with the downside of breaking easily if a fireball hits it and not being a renewable resource in the Nether. A recommended material is to use cobblestone, stone, and any deepslate variant as they are highly defensive against the ghast's explosion, and very easy to obtain. (I have only tested this with cobbled deepslate.)