Get client IP address from JSPTag(s): Servlet/JSP
<% out.print( request.getRemoteAddr() ); out.print( request.getRemoteHost() ); %>
You may not get the real client IP if a the client is behind a proxy, you will get the IP of the proxy and not the client. However, the proxy may include the requesting client IP in a special HTTP header.
<% out.print( request.getHeader("x-forwarded-for") ); %>