how to check authorisation

[somesh A]

In my servlet i need to get user's IPAddress,i've tried like this request.getRemoteUser(),but this is retuning null because of authorization problem.i don't know much about JAAS api.can anybody help me to solve my authorization problem ie how authorize user?

[Steve11235]

Authorization is typically something provided by your Web Application Server. The details will depend on your WAS and what access you have to authentication sources, such as an Active Directory server.

I went through the pain of figuring out how Tomcat supports authentication, and it proved to be worth the effort. I ended using a home-grown user database that Tomcat's authorisation process accessed through UserPrincipal classes I created. Doing so was more secure, easier for the users, and it required no coding in the applications themselves.

[chizbox]

Sir may i ask how could i possible do this? thank you!