Re: Connection to ejb server via rmi client through nat

[Victor Langelo]

It's unclear from your message whether the address of the server or client is being translated. If the client address is being translated, you should have no problems with client to server connections.

If the server address is being translated, you've got a problem. Most implementations of RMI servers embed the server address and port in the client proxies. The client then receives a remote object (actually a proxy implementing Remote) which contains the server's private address. The NAT router doesn't have anyway to translate the address embeded in the proxy. So when the client attempts to use a method of the remote object, the request is sent to the server's private address.

There are two general solutions to this problem:

1. Use an RMI proxy server which will receive the request on a public address and forward it to the server's private address. Search the list archives of announcements of RMI proxy servers.
2. Modify the proxies or RMI server to embed or translate the server's private address to the public one. Most servers will allow you to specify a RMIClientSocketFactory. A quick hack that has worked for me in the past is to implement a RMIClientSocketFactory that translates the address it's given in the createSocket method to the public address, then creates a socket using the public address.

Of course, you should check with your server vendor to see if they have already developed a solution.

--Victor


deepak wrote:

I am trying to connect to the EJB Server from a rmi client and there is
NAT(Network Address Translator) in between. Due to this NAT , this thing
doesnt work. Any idea how i can work this out.

Thanks.

Deepak.