How to do this on a Minecraft server?

I have been making a survival server and i noticed that in gamemode 0 mobs attack me at my spawn. I know how to turn off mobs but I've seen on servers where half of the world is peaceful and the other half is regular how do I do this. Do I need a certain plug in or something?

Guest

If it is random world gen then this plugin will not work but it is a plugin that allows you to change game rules and modes at certain render distances and map quadrants although I'm not to sure what it is sorry.

Alex

I believe this is possible with the mod Singleplayer Commands, WorldEdit, and World Guard. World guard allows you to set spaces of volumes where you can set specific properties, one of which could control mob spawning. This is just one way to do this. This is a commonly used practice in large servers.

Jim