Is it possible to prevent people with cracked copies of the game from joining my server?

I want to start an open Terraria server, and would like to keep players running cracked clients off of my server.

Is there any way that I can accomplish this? I am using the Steam version, if it makes any difference.

Solution 1:

I ended up testing this myself.

Unfortunately, illegal copies of the game can access my server.

Upon examining packets received by server with WireShark I found nothing that would indicate difference between a cracked client and my steam copy.

Since there is no way to distinguish this, there would be no way for only legal owners of game to play with out some sort of tool, that would validate the game at client-side.