Remote debugging is one of the most important feature of REALbasic Professional edition. If you have a SSH server running on the same subnet as the target computer, it is possible to debug between two computers on different networks, even if they only have private IP addresses. Here's how it works:

First of all, in the Preferences menu of REALbasic IDE, configure a new Debugging session as follows:

* Network Interface: Default
* Machine Name: Port Forwarding (or anything as you like)
* Address: localhost (or localhost:44553)

Secondly, run the Remote Debugger Stub (RDS) on the target computer.

Then, run the SSH client on the debugger computer as usual, but with two local and remote forwarding options:

-L 44553:<a private IP address of the target machine running RDS>:44553
-R <a private IP address of the SSH server>:13897:127.0.0.1:13897

Finally, choose "Project" > "Run Remotely" > "Port Forwarding" in the IDE. Now your program runs on the target machine and can be debugged remotely!

If you see the Runtime Error message box saying "could not locate the target IDE for debugging", maybe your SSH server is denying port forwarding requests on the remote side; you should configure the SSH server's "GatewayPorts" parameter (if you're using OpenSSH) to "clientspecified" or "yes" instead of "no" (which is the default) - note that the "root" privilege is required to change the configuration. You may also need to check the firewall configuration on both ends as well.