Your stupid -.-
Stop flaming. If you are going to make a post just to tell someone how stupid they are, don't post then.
7. Do not flame - If the entire point of your post is to tell someone what an idiot they are, don't bother.
And no, this doesn't look possible, since the players don't connect to you, they connect to the server. Unless if the server has an add-on, that on using a client-sided add-on, will send a request to the server asking for an user's IP and displaying it to the client.
Also, this shouldn't happen. It's too much of a privacy violation.