Salt grants some protection against chaotic evil undead and extraplanor creatures. It may be used to block doorways or create circles of protection. One pound of salt is needed to line one side of a five food square, blook one doorway, or block two windows. Chaotic evil entities with no particular desire to enter such a protected place will simply avoid it and choose another target. Should they have a reason to cross the barrier, if they are 4HD or less they must make a saving throw vs Paralyzation. If they fail, they may not cross it for one turn. 8HD entities may attempt a save every round. Higher level creatures are not affected.
Iron & Iron Nails
Iron nails hung above doorways have an identical force against shapechanging creatures of all types, including spellcasters currently under the effect of any shapechanging enchantments, etc, as salt does to chaotic evil creatures.
Iron weapons and tools when wielded as weapons do one  additional point of damage against all forms of incorporeal undead.