RMI get client IP Address

[B Ortet]

I guys, i need to get the client IP address, that is connecting to my Server. What I found, was to use the method RemoteServer.getClientHost().
But for sure is retriving the Server IP address.
If I run the RemoteServer.getClientHost(), in the client side, i get the error: java.rmi.server.ServerNotActiveException: not in a remote call.
There is a way to get the Client ip address?

thank you

[Tim Holloway]

Welcome to the Ranch, Bruno!

There's little point in trying to obtain the client's IP address. Thanks to network address translation my machine's actual IP address might be 192.168.1.113 but servers will see me as 96.90.14.153.

So If you're planning to use the client's IP for authentication or authorization, don't bother. For RMI, it's better to provide an API method that will return a token when passed valid user credentials and pass that token back to the server on subsequent RMI calls.

And use a secure transport for the RMI, to avoid having network snoopers lift the token and do Man-in-the-Middle attacks.

[B Ortet]

Thanks man. Ive been using ranch for some time now, to look on some opinions about the the java certifications and to clarify some doubts. Only now i registered though...
Im doing a school project. And its requiried for me to log the client ip address that log into the system. But as you said, the NAT protocol, will take some action here.
I forgot about that, and i was thinking about using the

InetAddress.getLocalHost();

and get the Client ipAddress and send it with the login credencials.
Thanks to you i see now its a bad ideia...

For the transport security ill check it later and get back to you.

[Tim Holloway]

The nominal source IP address is embedded in every network packet, of course, just not the definitive one. And, while I'm at it, I should probably point out that there are probably thousands, maybe millions of computers that have the IP address 192.168.1.131, since it's a non-unique address.

There are two common uses of the nominal source IP address, though. While they cannot uniquely identify who's connecting, they can be used to figure out what part of the world the request is probably coming from and which Internet Service Provider handled the originating traffic.

This nominal IP can then be used to fine-tune firewalls - for example, I had to completely block all emails originating from South Korea since all I ever got from that country were immense quantities of spam. It can also be captured in server logs, where it might be used for market analysis, for example. Of course, RMI is really only intended for internal LAN use, so RMI server implementations normally don't log at that level.