Placeholder for (SCE), Sakki's Client Essentials.
SCE is currently in Development phase for Forge / Sponge.
This mod / plugin is used as a way to protect a players client, while giving the Server Admin the ability to approve of who can, or cannot connect. This is not hack proof, however, it is a means of preventing (or allowing) players from modifying their clients. There are also some other client functions that have been implemented, and will list them all out once I've ported the mod over.
Because this is dependent upon permissions, and because I don't think perms have been incorporated yet into Sponge, I may have to rewrite some portions
Full version : 1.6.4 (This is an old Beta version that I was working on. Never completely finished, logic still needed some tweaking, but works for the most part):