Limit external communication to specified ports

The system programmer can specify the ports on which the RSE server can communicate with the client. By default, any available port is used. This range of ports has no connection with the RSE daemon port.

To help understand the port usage, a brief description of RSE's connection process follows:
  1. The client connects to host port 4035, RSE daemon.
  2. The RSE daemon creates an RSE server thread.
  3. The RSE server opens a host port for the client to connect. The selection of this port can be configured through the _RSE_PORTRANGE definition in rse.env.
  4. The RSE daemon returns the port number to the client.
  5. The client connects to the host port.