you can use the following in your index.jsp:
request.getRemoteHost() - for Hostname
request.getRemoteAddr() - for IP address
But you can't get the logged in user.
This is because, the HttpServletRequest doesn't store
However, it can be accessed in client's JVM as a
system property, "user.name".
So, if you really want it, you have to make the client
knowingly or unknowling execute a program or command which
returns the logged in user and send it to the server.