How To Ask A RemoteHostIP???

I am writing a more involved multi-user chat. Much like the one that I am modifing that I had found on the vbForums website. I wish to enter the following data, into the TextBox, which is called "txtMsg.Text". The text is; "get Server ip".

I wish to change the word Server to become the username of the remote user that is only active and online on the server of course. But I don't know their ip address, becuase this will be found out at run-time and not at design time.