I have a problem getting my RMI application to work. Having a RMI Server app running in a VMWare that forwards port 1099 in a NAT enviroment. Physical machines IP on the outside = 188.8.131.52 Physical machines IP in local area = 192.168.0.1 Virtual machines IP = 192.168.0.100
I start a rmiregistry on my virtual machine and since port 1099 is NAT-forwarded I can connect to the registry from the outside using telnet 184.108.40.206:1099.
I startup my serverside rmi-app on the virtual machine
and in my app I do the following binding:
This work fine with HOST=127.0.0.1 or HOST=192.168.0.100 but when setting HOST=220.127.116.11 (the public IP address), startup fails with:
When server is running with HOST=127.0.0.1 or HOST=192.168.0.100 (like I said using HOST=18.104.22.168 doesn't work at all, the server is not allowed to bind) the binding from the outside using my client-app works (bind to 22.214.171.124 the public IP) , but however when trying to actually use the remote object the client throws the following exception: Using HOST=127.0.0.1 on serverside
or when server HOST=192.168.0.1
I assume using the public IP on serverside by setting HOST= to 126.96.36.199 is the right way, but as stated above binding to the rmiregistry is not allowed! What am I missing?
Thanks alot, your help is very much appreciated. Cheers, Tobi
You have to ensure that your firewall is forwarding your RMIRegistery port (1099), and you also have to set the java.rmi.server.hostname property on the command line when you run your server. The value of java.rmi.server.hostname should be the external address of your firewall. This allows your server to "know" it's running locally, but to ensure that any stubs generated will use the IP address of your firewall. When clients use the stubs, they "talk" to the firewall, and the firewall forwards to your real server.
Write once, run anywhere, because there's nowhere to hide! - /. A.C.
Joined: Jan 25, 2006
Hi, thanks for your reply.
Well, ok. So my assumtion of using the public IP is correct. But when doing so on server side, this exception occurs when starting the server:
[ January 26, 2006: Message edited by: Tobias Weih ]
The value of HOST in your code above has to be the IP of the machine the server code is running on. From the error above it looks like this value isn't correct.
// HOST *must* be localhost String HOST = "192.168.0.100"; // or just 127.0.0.1 Naming.rebind("//"+ HOST + ":1099/" + CommandBroker.NAME, this);
The java.rmi.server.hostname property that you specify on the command-line will be the IP of your firewall, though...
Are these the values you are specifying? [ January 27, 2006: Message edited by: Nathan Pruett ]
Joined: Jan 25, 2006
my problem is solved, finally. There are a couple of things that caused my troubles: First of all, binding to localhost is correct, since the host-address is only used to contact the registry for the rebind operation. When using the public IP to bind it fails because the connection to 188.8.131.52 is being routed out to the NAT and back in again, so its origin appears non-local. And as a rule binding to a non l ocalhost is forbidden. As far as an external client being able to use the bound stub, the important setting is the java.rmi.server.hostname system property, which controls the host name or address that gets put into the stubs for remote objects exported in this VM. Thus it has to be 184.108.40.206 in my case. Another very interessting thing is the need to explicitly define the port the Remote Object uses. Therefor I call super(1099) instead of just super(). See http://archives.java.sun.com/cgi-bi...mi-users&P=3663 for details. Many thanks to Peter Jones!