This question already has an answer here:

I currently live in a Nether Ruin. My not-so-sweet home always seems to be overrun by Zombie Pigmen, Wither Skeletons, and Blazes. What am I supposed to do to keep them away?

merged by Raven Dreamer May 23 '13 at 1:20

This question was merged with How can I keep monsters out of my nether regions? because it is an exact duplicate of that question.

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