Lockit is a mod used by the pack specifically for server functionality. It allows you to lock and unlock chests and doors, and to some extent, protect areas. You can find the original Minecraft Forum thread post for the mod here.

The Epic Mod Pack ServerEdit

On the server, there are currently only lock blocks and hanged locks implemented. This is because the area protection provided by Lockit is currently very unstable, and it creates many issues such as server crashes. However, chisels and block engraving is still functional.