http://java.sun.com/j2ee/sdk_1.2.1/techdocs/api/javax/servlet/ServletRequest.html java.lang.String getRemoteAddr()
Returns the Internet Protocol (IP) address of the client that sent the request.
java.lang.String getRemoteHost()
Returns the fully qualified name of the client that sent the request, or the IP address of the client if the name cannot be determined.
for example the first one may give
213.78.93.105
whilst the second might give
213-78-93-105.friaco.onetel.net.uk