Running the Run External Application action on a node in another domain

The goal here is to run putty on an APE in another domain so that scripts can be run on some linux servers.

I can run notepad.exe (as a test) on any node in the domain where the MPE is. I cannot run notepad.exe on any other domain. Is this a port issue? Or will it just not work across domains? I am using an account for that domain.

thanks