Minecraft – How to keep pets from teleporting

Since version 1.5, this hasn't been much of an issue, as that release introduced a rule in the mobs' AI to avoid rails unless they are chasing after the player. Although I have still found Zombie Pigmen appearing on the tracks, this is now not as much of an issue as it was in previous versions.

Zombie Pigmen are able to spawn on rail tracks, so removing the walking path on the side will do nothing. But as has been mentioned, adding blocks above your tracks will prevent them from spawning and help keep them from walking onto your tracks 100% of the time. This is a common "fix", and has been around for quite a while, and it doesn't seem like the developers have any plans to stop this fix from being possible.

The following blocks can safely be placed above the tracks, and will not suffocate you:

• Glass panes (I would really recommend this one, since they are "cheaper" than glass blocks, works with stained glass panes as well)
• Glass blocks (works with stained glass as well)
• Glowstone blocks
• Leaf blocks
• Iron bars
• Fences (of all materials)
• Half-slabs (of all materials, note that they must be single, NOT double slabs)
• Stairs (of all materials)
• Trap doors
• Pistons (both extended and retracted)

There are other blocks that would work, such as Beds, Chests, TNT, or Enchantment Tables, but I have excluded them from the list due to being impractical.

Here is a method I came up with while pondering your question, be warned though, I haven't had a chance to test it out, but I think it might work. Here are the commands and command block setup:

1: /testfor @e[type=snowball]
2: /execute @e[type=snowball] /tp @p <x> <y> <z>
3: /setblock ~ ~ ~ redstone_block 0 destroy

Remember to put numbers next to the ~ symbols to tell the command where to place the redstone block relative to the command block so it's constantly running the command in the next command block. Now here's the setup, please note that being able to to what I am telling you to do does require basic command and redstone knowledge:

1 = command block #1
2 = command block #2
3 = command block #3
[] = redstone comparator
{} = redstone repeater with a 2 tick delay
# = redstone block

3#1[]{}2

Also, you might want to run this command as to not lag your server:

/gamerule doTileDrops false

I also forgot to mention, you must be playing in snapshot 14w21a or later.