Created attachment 28159 [details]
Support RMI client port configuration and using loopback interfaces.

In order to better support SSH-tunneling of the RMI communication channels used in remote testing, please see the attached patch which makes the following two changes:

1) Just as the RMI ports used for the server component can be specified using "server.rmi.port" and "server.rmi.localport" parameters, introduce a "client.rmi.localport" parameter that can control the RMI port used by the RemoteSampleListenerImpl.  Currently, the port is randomly assigned, which makes it tricky to tunnel traffic to that port over a SSH tunnel.

2) The current behavior of RemoteJMeterEngineImpl is to throw an exception if the remote engine attempts to listen to traffic over the loopback interface.  However, we often need this behavior when tunneling RMI traffic over an SSH tunnel as the remote endpoint will actually be a port on the local machine, which is subsequently tunneled.  To support this functionality, I propose allowing the localhost loopback interface to be used if it has been specified directly using the "java.rmi.server.hostname" parameter.  Thus, we keep the current default behavior of warning the user if their remote endpoint is only listening on the local interface, but allowing users who know what they are doing to specify the local interface if they really want to.