It is possible to protect hidden portals and chests, so that they appear as stone to anybody using x-ray. To do this, they must be completely covered, and not touch any transparent blocks at all.
Portals obviously require 2 free spaces inside, to solve this problem, we count levers as solid blocks, so placing 2 levers inside the portal and then covering the rest of the portal will prevent it from being visible. You can test that the portal is properly hidden by covering it up as you would, relogging, and then digging down to it. You should be able to notice that the 'stone' blocks turn into obsidian as you dig down.
1. So i must recover with stone in the overworld, but what about the end ? Endstone ? And netherrack for the nether ?
2. Some people told me x-ray protection isn't really working anymore ?
The portal function is still great if the first one of portal onion routing is far for spawn (like traveling a bit in the nether for it) and the others on lowest Y possible so we can hope people using X-Ray are flying too high to see them.
The lava layer above custom portal is nice tip too, makes it less visible for someone using X-Ray.
